Chap - 35, - 36 - Companion Guide to B31.1 - 4th Ed

CHAPTER

35

35 COVERAGE

The ASME B31.1 Power Piping Code is the first of a series ofpiping codes which cover piping for various industries. This chap-ter covers ASME B31.1 Power Piping Code [25] and all citationsto figures, tables and para (s) in this chapter refer to [25], unlessotherwise mentioned.

The rest of the series which include the following are coveredin subsequent chapters of this publication:

• B31.3 Process Piping [26]• B31.4 Pipeline Transportation Systems for Liquid Hydrocar-

bons and Other Liquids [27]• B31.5 Refrigeration Piping [28]• B31.8 Gas Transportation and Distribution Piping Systems [29]• B31.9 Building Services Piping [30]• B31.12 Hydrogen Piping and Pipelines

This series of piping codes started with the Pressure PipingCode which was first published in 1935. More information on thehistory is printed in the forward of ASME B31.3 [26] as well asothers in the series.

At the end of this chapter 35 there are references pertaining toall of the parts of this Chapter. Whereas some of these referencesare directly applicable to the discussions contained in this chapterseveral others are noted for additional information.

35.1 INTRODUCTION

This Chapter is written with the assumption that the reader hasthe 2010 edition of the Power Piping Code at hand. The intentionof the Chapter is to simply supplement and provide additionalinsight to the proper use of the Code. The brief history of theCode is covered in the Forward of the ASME B31.3 Process

Piping Code [26]. But, to drive home a point, the first edition ofthe Power Piping Code was published in 1955.

In this chapter, the word “Code” is used to refer to the ASMEB31.1 Power Piping Code [25]. A review of the Code table ofcontents reveals the general layout covering design, materials,fabrication, erection, inspection, and operation and maintenance.The operation and maintenance chapter, Chapter VII, was addedin December 2007 and for the first time specifically makesmandatory the proper maintenance of power piping. The term“operation” in the chapter title is sort of carried along for the ridein that the chapter simply requires that the piping systems beoperated within design.

A number of changes have been made to the Code since the 3rdedition to this companion guide. Concerns about the degradationof the heat affected zone (HAZ) of seam welds in piping systemsthat operate in the creep regime prompted the addition of safetyfactors.

The Code began a two year publication cycle with the 2010edition. Prior to 2010 addendums were issued annually.

When is the Code Mandatory?When an authority says so. In the United States of America,

each state determines whether the Code will be required by law.The National Board issues a Synopsis of Boiler and PressureVessel Laws, Rules and Regulations. The September 26, 2011edition indicates nearly all states and all of Canada require someedition of ASME B31.1. The Code becomes mandatory 6 monthsafter publication.

The Forward and Introduction of B31.1 provide and very goodstarting point for the first time Code user. The intent of the Codeand how the Pressure Piping Codes are divided are provided there.For example, the Introduction explains that there are currently 8piping codes (sections) within the B31 Code for Pressure Piping. AStandards Committee is responsible for all of the “book sections”,under this is the section committee which is responsible for theCode book specific to a type of pressure piping. The scope of theB31.1 Power Piping Code is outlined and the procedures for askingthe Committee a question and for Code Cases are included there.These two sections are worth reading and should not be skipped.

A review of the Committee Roster will provide a view of thestructure of the Committee. The Standards Committee is the maincommittee over all of the “book” sections. The Power PipingSection Committee is further divided into subgroups to cover spe-cific areas of expertise such as design, materials, and fabrication.

ASME PIPING CODE: B31.1, POWER PIPING

Jimmy E. Meyer and Joe Frey1

1Charles Becht IV was the author of “Chapter 16” titled “B31.1 POWERPIPING” for the original, second and third editions. Chapter 17 of the thirdedition has been revised in its entirety and renumbered as Chapter 36 inthe current fourth edition. As noted in the title this chapter 35 for the current edition, it is authored by Jimmy E. Meyer and Joe Frey. - (Editor)

PROPRIETARY A

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owner

Text Box

Dear Mr. James Ellenberger: The pages of Chapters 35,& 36 of the "4th Edition of Companion Guide" in the following pages are for use in the preparation of Chapter 23: "B-16 Standard" and should not be used for any other purpose. - K. R. Rao (Editor: 3-26-13)

35-2 • Chapter 35

In the front of each edition of the Code is a Summary ofChanges which is just that; a summary of changes from the edi-tion just prior to the edition in hand. This summary can be usefulwhen researching a certain requirement of the Code to determineif it is the result of a recent change to the Code.

Following the main body of the Code are both Mandatory andNonmandatory Appendices. The appendices provide a great dealof information and the Code user should be familiar with the con-tent. The mandatory appendices are called out as capital letters Athrough J. These include allowable stress, thermal expansion data,moduli of elasticity and stress intensification factors to name a few. The nonmandatory appendices are denoted by romannumerals II through VII. The nonmandatory appendices includeinformation on safety valves, nonmetallic pipe, corrosion, andoperation and maintenance and more. It bears repeating that theappendices provide a lot of very useful information because theseare often overlooked by the beginning Code user.

The introduction of each of the book sections gives a briefdescription of the scope of the book sections and identifies theresponsibility for the owner to select the applicable Code sectionfor the design of piping related to their facility. This is one of sev-eral important responsibilities assigned to the “owner” who isdefined in the first section of B31.1 Paragraph 100.2. Anotheruseful piece of information to understand is the numbering ofparagraphs, figures and tables in the piping codes. All of the num-bered book sections started from a single pressure piping code asnoted above, as the specific book sections were split apart for spe-cific types of services or industries, there was an attempt to main-tain the paragraph numbering with the exception of first numberin the series. For example all of the paragraphs in B31.1 are in the100 series likewise all of the paragraphs in B31.3 [26] are in the300 series. This is not an absolute, but it will give a good startingpoint for the reader who uses more than one of the ASME B31series in the reader’s career.

The use of the term Piping is meant to apply to more thanPipe. Pipe, Piping, Piping Components, Piping Elements, PipingInstallation, and Piping Systems may all be referred to as Piping.Another important point which is made in the introduction ofB31.1 as well as other book section is “the Code is not a designhandbook”. This is not emphasized sufficiently, and will berepeated a few more times throughout this chapter. Since this is a companion guide to the code, requirements will not beduplicated, instead frequent references to the applicable para-graphs and some insights to the requirements or a simpler wayto look at them to help the user understand them will be made.Many of the explanations may be oversimplifications and shouldnot be taken as the complete code requirements. The code isupdated frequently and is considerably more thorough than thisguide.

After the Introduction, the Code is organized much the same asa design and construction project for the first Chapters:

Chapter I, Scope and DefinitionsChapter II, DesignChapter III, MaterialsChapter IV, Dimensional RequirementsChapter V, Fabrication, Assembly and ErectionChapter VI, Inspection, Examination, and TestingChapter VII, Operation and Maintenance

Treatment in this chapter follows the same order as shownabove. A list of references is provided at the end of the chapter forthe reader to explore the topics in more detail.

35.2 SCOPE AND DEFINITIONS

Para. 100.1 below specifically identifies the types of plants wherethe ASME B31.1 Power Piping Code would normally be used.

Rules for this Code Section have been developed consideringthe needs for applications that include piping typically foundin electric power generating stations, in industrial and insti-tutional plants, geothermal heating systems, and central anddistrict heating and cooling systems.

The Code has Figures 100.1.2 (A.1 through A.3) [25] whichdefine 3 classifications of piping:

• Boiler Proper• Boiler External Piping• Nonboiler External Piping

One example of these figures is provided in Figure 35.2 below.The three figures A1, A2 and A3 [25] are required because the

extent of the Boiler and Boiler External piping varies dependingon the type of boiler. Boiler External Piping (BEP) is very impor-tant to the safe operation of the Boiler, so it carries additionalQuality Assurance and documentation requirements. Boiler Ex-ternal Piping is sometimes referred to as Critical Piping by theindustry. Generally, Critical Piping also includes the Cold and HotReheat piping associated with many power plants. Currently theCode does not include Cold and Hot Reheat as Boiler ExternalPiping, however this may change in the future.

Definitions are also included in this section and are useful infully understanding some Code requirements. A relatively newdefinition which was added with the addition of Chapter VII is“Covered Piping Systems”.

Covered piping systems (CPS): These are piping systems onwhich condition assessments are to be conducted. As a mini-mum for electric power generating stations, the CPS systemsare to include NPS 4 and larger of the main steam, hotreheat steam, cold reheat steam, and boiler feedwater pipingsystems. In addition to the above, CPS also includes NPS 4and larger piping in other systems that operate above 750°F(400°C) or above 1,025 psi (7 100 kPa). The OperatingCompany may, in its judgment, include other piping systemsdetermined to be hazardous by an engineering evaluation ofprobability and consequences of failure.

35.3 DESIGN

35.3.1 Chapter II, Part 1, Design ConditionsThe paragraph 101 provides a short explanation of conditions

or considerations for the design of piping systems. It is a fairlycomprehensive list, but the owner or designer should always be onthe lookout for unique conditions which might not be addressed.

35.3.2 (Para. 102) Design CriteriaThis section defines the basis of the allowable stresses, quality

factors, etc. to be used for the design of piping systems. It alsoincludes some references to listed and unlisted components andan allowance for short term variations. The user is cautioned to besure they have enough understanding of future operation of thesystem before they apply these allowances. Generally boilers orpower plants are designed for a 20–40 year life or more. Unlessthe variations are self-limiting (for example a relief valve dis-

PROPRIETARY A

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COMPANION GUIDE TO THE ASME BOILER & PRESSURE VESSEL CODE • 35-3

charging), it is difficult for a designer to assure himself of theduration of variations to design conditions.

35.3.2.1 (Para. 102.3.2) Limits for Sustained and Displace-ment Stresses This might be the most important paragraph tounderstand the analysis and design requirements in the Code. Thesimplified analysis requirements in the Code are separated intoSustained Stresses or Loads which will act until a system fails if itexceeds the limits of the material and Displacement Stresses orLoads (self limiting) which have a defined displacement and willnot continue past this limit. Failures from displacement stressesare by fatigue or cycling until the fatigue limit of the material hasbeen exceeded.

Examples of Sustained Loads and Stresses:

• Internal Pressure (hoop stress) Sh

• Internal Pressure (longitudinal stress) (SL Para. 102.3.2(A.3))• Bending Stress from weight (longitudinal) (SL Para. 104.8.1)• Bending Stress from occasional loads such as wind, snow and

Seismic (104.8.2)

Examples of Displacement Stresses (Self Limiting)

• Stresses due to thermal expansion or contraction. (Para 119)• Anchor movements caused by settlement, equipment move-

ment, etc.:

Condenser

From feedpumps

Alternativespara. 122.1.7(B.9)

Administrative Jurisdiction and Technical Responsibility

Para. 122.1.7(B)

Start-up systemmay vary to suitboiler manufacturer

Economizer

Convectionand radiantsection

Reheater

Superheater

Turbine valve orCode stop valvepara. 122.1.7(A)

Turbine

To equipment

Boiler Proper — The ASME Boiler and Pressure Vessel Code (ASME BPVC) has total administrative jurisdiction and technical responsibility. Refer to ASME BPVC Section I Preamble.

Boiler External Piping and Joint (BEP) — The ASME BPVC has total administrative jurisdiction (mandatory certification by Code Symbol stamping, ASME Data Forms, and Authorized Inspection) of BEP. The ASME Section Committee B31.1 has been assigned technical responsibility. Refer to ASME BPVC Section I Preamble, fifth, sixth, and seventh paragraphs and ASME B31.1 Scope, para. 100.1.2(A). Applicable ASME B31.1 Editions and Addenda are referenced in ASME BPVC Section I, PG-58.3.

Nonboiler External Piping and Joint (NBEP) — The ASME Code Committee for Pressure Piping, B31, has total administrative and technical responsibility.

FIG. 35.1 CODE JURISDICTIONAL LIMITS FOR PIPING — AN EXAMPLE OF FORCED FLOW STEAM GENERATORS WITHNO FIXED STEAM AND WATER LINE (Source: ASME B31.1, 2010 Figure 100.1.2 A.1)

PROPRIETARY A

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35-4 • Chapter 35

The above examples are limited to a Stress Range which isdefined by Para 102.3.2(B) Equation (1A) or (1B) [25].

SA � f(1.25Sc � 0.25Sh) (35.1a)

SA � f(1.25Sc � 01.25Sh–SL) (35.1b)

The limits for sustained loads are roughly 2/3 of the yieldstrength of a material, or 1/3.5 of the tensile strength of a materialand are provided in Appendix A of ASME B31.1 [25] for listedmaterials. The limit for displacement strains (self limitingstresses) can be as high as twice the yield strength of the material.Equation 35.1a is the first equation in the code and defines theallowable displacement stress range.

In equation 35.1a: SA � f(1.25Sc � .25Sh)Sc and Sh are the basic allowable stress for the materials at min-

imum and maximum expected temperatures.“f” is a fatigue factor based on the number of cycles expected

during the service life of the system. The fatigue factor “f” is 1 orless based on equation 35-2 (which is based on equation ASMEB31.1, 2010 equation 1(C) page 14 that is noted below) [25]:

f � 6/N0.2 � 1.0 (35.2)

f � cyclic stress range factor for the total number of equivalentreference stress range cycles, N; (this applies to essentiallynoncorroded piping. Corrosion can sharply decrease cycliclife; therefore, corrosion resistant materials should be consid-ered where a large number of significant stress range cycles is anticipated. The designer is also cautioned that the fatiguelife of materials operated at elevated temperatures may bereduced.)

N �total number of equivalent reference displacement stress rangecycles expected during the service life of the piping.

The analysis requirements for both Sustained and Self Limitingloads will be discussed later in this chapter, but the two load casesare treated separately by the Code with one minor exception. Theexception is equation (1B) of [25]:

SA � f(1.25Sc �1.25 Sh –SL). (35.1b)

This equation still does not do anything to combine the twoload cases. If studied carefully, it roughly increases the stressrange from 1.5 times the basic allowable stress to 2.5 times thebasic allowable stress minus the longitudinal stress from the com-bination of sustained loads. So again, the code does not combinesustained and self limiting load cases, it only allows an increase inthe displacement stress range allowable for any unused part of thesustained stress allowable. The user is urged to review the require-ments of this paragraph carefully to fully understand the differ-ence between the two types of loading and the code treatment ofthem. This will also be discussed during the analysis requirements(Para. 119) later in this chapter.

References 8, 9, 10, and 14 provide more in depth informationon the stress range concept and associated stress intensificationfactors discussed later.

As a footnote it can be mentioned that seismic loads are usu-ally treated as sustained loads by various Codes, however a lot ofresearch indicates seismic failures are more closely associatedwith fatigue or self limiting loads.

35.3.3 Part 2 Pressure Design of PipingComponents

35.3.3.1 (Para. 104) General The easiest way to meet the pres-sure design for a component is to use components which are manufactured to a standard listed in Table 126.1 [25]. These listedstandards provide pressure temperature ratings for the components,either in the form of a table with coincident pressures/temperatures(for example B16.5, B16.47, etc.), or ratings associated with com-patible seamless pipe (for example B16.9, B16.11, etc).

Unlisted components may be used, however a lot more respon-sibility is put on the designer to verify they are good for the pres-sure, temperature and other loading requirements in the code.Reference 7 provides additional guidance for Unlisted Compo-nents. The number of reference standards associated with pipingdesigns are quite significant, Table 35.1 gives some examples ofhow the piping codes are interrelated for some common carbonsteel (CS) and stainless steel (SS) Pressure Rating/DimensionalStandards, Material Forming Standards and Material Grades.

35.3.3.2 Pressure Design

35.3.3.2.1 Straight Pipe. This section defines a lot of termsassociated with the calculation of the required wall thickness forinternal pressure.

During the development of the Code approximately 30 differ-ent equations were considered for the calculation of required wallthickness. If the piping were infinitely thin, the simple equation of“t � PD/2SE” where t � minimum calculated wall thickness, P �design pressure, D � Pipe Outside Diameter, SE � basic allow-able stress (including weld quality factors) would provide accurateor conservative results. Since it must have some thickness, theCode settled on equation (7) “t � PD/2(SE � Py) � A” because itis relatively simple and provides good results compared withmore complicated formulas. The corrosion allowance “A” is alsoincluded in this equation. Table 104.1.2(A) [25] provides valuesfor the “y” factor which is .4 for most low temperature ductilematerials. Equation (8) is also provided for the user if they wouldlike to start with the ID and calculate a minimum wall thicknessand Equations 9 and 10 are provided to calculate a design pres-sure for a given thickness of pipe.

Table 104.1.2(A) [25] limits the use of the y factor from thetable to Diameter to wall thickness ratios of 6 or greater. For thick wall designs where this requirement is not met, general note 2 provides an alternate formula. In pressure ranges re-quiring these thick walls, the user should consider such factors as theory of failure, effects of fatigue, and thermal stress. In ASME B31.3, Chapter IX [26] was developed to provide extra guidance/requirements for these high pressure applications.

Longitudinal-Welded pipe in the Creep Range are addressed inPara. 104.1.4 where an additional factor of safety is added withEquations (11 and 12) [25]. The factor “W” is added to the basicallowable stress and quality factor to address problems with thesewelds in the creep range.

References 1, 11, 13, 14, and 17 provide more detailed expla-nations and the theory behind these equations.

35.3.3.2.2 Straight Pipe Under External Pressure. For externalpressure whether from a vacuum condition in the pipe, or jacketingwith steam, para. 104.1.3 of the Code refers to ASME Boiler andPressure Vessel Code Section VIII for the design requirements.

PROPRIETARY A

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See References 2, 3, 4, 5, 6 and 17 for addition information onExternal Pressure or Vacuum Design of piping and components.

35.3.3.2.3 Curved Segments of Pipe. Para. 102.4.5 has similarequations to those for straight pipe, these are provided for pipingbends. While these equations are a little more complicated thanstraight pipe, repeating them here will not provide the user muchadditional value. References 17 and 22 provided at the end of thischapter will provide more in depth explanation into the theory ifrequired.

35.3.3.2.4 (Para. 104.3.1) Branch Connections. Para. 104.3.1of the Code provides rules based on area replacement as an alter-nate to using listed components from Table 126.1 [25] within theirpressure temperature rating,. Area replacement means when a holeis cut in the pipe wall, area removed is replaced within a specificdistance of the area which was removed. The theory here is thehoop stress which is the basis of the wall thickness calculation willremain constant if the area remains constant. There are about fourpages of figures and definition of terms/areas associated with thisconcept. ASME B31.3 Appendix H [26] provides 5 sample prob-lems for branch connection reinforcement. The formulas and fig-ures are not identical, however the concept is the same and theexample may help. What makes it look complicated are all of theallowances on the pipe wall and the possibility the branch is not ata right angle to the pipe centerline. If not all of the existing wall isrequired for pressure design (i.e. the actual pipe wall thicknessexceeds the minimum wall required), then this extra wall thicknessmay be used for area replacement. Figure 35.2 is provided as anexample of one of the figures used to explain this concept.

A simpler approach would be to calculate the minimum wallthickness required for the run pipe or header. If the actual wall

thickness is not at least twice the calculated minimum wall thick-ness, most likely some area reinforcement or replacement isrequired. Unless it is very close, the author recommends specifying100% replacement of area. The reinforcement area is basically onebranch diameter from the centerline of the branch on the header,and 2.5 times the wall thickness of either the branch or the header.This is fairly limiting, however if the reinforcing pad is made fromthe same material and thickness as the header, and specified with awidth equal to the radius of the branch, it will produce a pad whichwill replace all of the area which was removed. The user is alsocautioned the area replacement rules apply to the pressure design,the branch connection will also have to be evaluated for other sus-tained loads as well as the displacement stress range. This topic willbe address more in other parts of this chapter.

ASME B&PV Code, Section VIII, Div. 1, Div. 2 and Div. 3 allprovide alternate methods of evaluating the intersection of cylin-ders for pressure and external loads. These methods vary from asimilar simplified approach to detailed finite element analysis.

35.3.3.3 Analysis of Piping Components Sustained andDisplacement loads were addressed briefly earlier in this chapter,in para. 104.8 formulas are provided to address Sustained Loads,Occasional Loads, and Displacement Loads (self limiting). Theanalysis requirements are also addressed in para. 119.

35.3.4 Part 3 Selection and Limitations of PipingComponents

Part 4 Selection and Limitation of PipingJoints

35.3.4.1 General Both parts 3 and 4 address various pipingcomponents or types of piping joints which might be limited to


TABLE 35.1 EXAMPLES OF LISTED STANDARDS FOR COMPONENTS AND MATERIAL

ComponentCarbon Steel (CS)/ Stainless Steel (SS)

Dimensional Standard/ Pressure Rating

Material/ Forming Spec. Material Grade

Pipe Carbon Steel ASME B36.10 ASTM A106 or A53

Grade B (most common)

Pipe Stainless Steel ASME B36.19 ASTM A312 Type 304, 304L, 316, etc.Forged Fittings 2” and Under (1) Carbon Steel ASME B16.11 ASTM A105 One GradeForged Fittings 2” and Under (1) Stainless Steel ASME B16.11 ASTM A182 Type 304, 304L, 316, etc.Formed Fittings 2 ½” and larger (1) Carbon Steel ASME B16.9 ASTM A234 Grade WPB to match pipeFormed Fittings 2 ½” and larger (1) Stainless Steel ASME B16.9 or

MSS SP 43 (2)ASTM A403 Type 304, 304L, 316, etc.

Flanges (Forged) 24” and smaller Carbon Steel ASME B16.5 ASTM A105 One GradeFlanges (Forged) 24” and smaller Stainless Steel ASME B16.5 ASTM A182 Type 304, 304L, 316, etc.Flanges over 24” CS or SS ASME B16.47 (3) See CS or

SS aboveSee CS or SS above

Forged Valves 2” and Under (1) CS or SS No Std. ASTM A105 and A182

Same as Forged Fittings.

Valves Flanged or Butt Welded Carbon Steel ASME B16.34 ASTM A216 Grade WCB to match pipeValves Flanged or Butt Welded Stainless Steel ASME B16.34 ASTM A351 Type 304, 304L, 316, etc.

Notes:1. The size ranges overlap, but generally 2” and under will be socket welded forged fittings and 2 ½” and over will be butt weld (wrought)

fittings. Verify with project or client specifications.2. MSS SP 43 does not have the same pressure rating, or quality control as ASME B16.9. ASME B16.9 should be specified for any pressure

or hazardous applications.3. Use caution on flanges over 24”. This standard has two sets of flanges series A and Series B. They do not fit up with each other! These

were previously MSS SP44 flanges and API 605 flanges.

PROPRIETARY A

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35-6 • Chapter 35

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PROPRIETARY A

SME

35-8 • Chapter 35

nonhazardous or nonflammable fluids, size limitation, pressureand temperature limits or where additional requirement might berequired. These requirements should be reviewed, but there is nogood way to summarize them. The user should familiarize them-selves with these requirements especially when they are preparingnew piping specifications, or working on a piping design whichdoes not have an approved piping specification.

35.3.4.2 Flanged Joints A Flanged Joint is one of the mostcommon methods for joining pressure piping which may requiredisassembly during maintenance activities. Table 112 [25] pro-vides requirements for mating flanges, bolting, flange faces andgaskets. The length of this table provides an indication of theimportance of proper flange design and assembly. A relativelynew Standard “ASME PCC-1, (Reference 23), also provides addi-tional guidance on proper flange assembly.

35.3.5 Part 5 Expansion, Flexibility, and PipeSupporting Elements

35.3.5.1 GeneralPara. 119.1

In addition to the design requirements for pressure, weight,and other sustained or occasional loadings (see paras. 104.1through 104.7, 104.8.1, and 104.8.2), power piping systemssubject to thermal expansion, contraction, or other displace-ment stress producing loads shall be designed in accordancewith the flexibility and displacement stress requirementsspecified herein.

The stress range concept is also explained in more detail in thischapter, but it was mentioned earlier when the allowable stressrange was defined. The statement made in the introduction of theCode “the Code is not a design hand book” is probably mostapplicable to this chapter. The user is also warned about the vari-ous piping analysis software products available to meet the analy-sis requirements of this section. These are great tools, and providea great deal more analysis options and load combinations thanwere available when the Code requirements were first written.

As was noted, the Code treats the displacement stress rangeseparately from sustained loads. Most analysis products availablenow combine sustained and displacement load cases in some way.In most cases, they also calculate a stress associated with this loadcase. There is no allowable stress associated with this load case inthe base Code. The explanation in para. 119.2. covers displace-ment strains, displacement stresses, displacement stress rangesand cold spring provide a good starting point for understandingthis concept. References 8, 14, 15, and 22 at the end of this chap-ter also will go into the basis of this concept in more depth.

35.3.5.2 Properties for Flexibility Analysis Appendix B, Cand D are referenced as the source for thermal expansion data,modulus of elasticity and flexibility and stress intensification fac-tors. This section also identifies specific temperatures to be usedfor the analysis. For example the expansion value for the stressrange is the algebraic difference between the minimum and maxi-mum temperatures for the thermal cycle under analysis, while theexpansion value for reactions is the expansion value from theexpected installed temperature to the maximum (or minimum)temperature under analysis. Appendix D contains the stress inten-sifications factors to be used with the simplified analysis methodsdescribed in the Code. These flexibility and stress intensificationfactors were first developed in the 1950’s. Many have not been

updated since then, so the Code permits the use of better data if itis available to the user. ASME B31J [31] provides a consistentmethod to experimentally develop stress intensification and flexi-bility factors. This standard is discussed in the next chapter, but itis worth noting the scope of this standard is being expanded toprovide updated factors which have been developed by morerecent research and will be available for use with all of the B31Code Sections. Also, see references 8, 14, and 22 at the end ofthis chapter for more information on the development of thesestress intensification and flexibility factors and the theories behindthem.

35.3.5.3 Flexibility Analysis These are interesting sections,and the user should be aware they were written and have been inthe Code since before there was easy access to Piping AnalysisSoftware. The analysis software available in the early 1970’s (andbefore) required a main frame computer and piping input deckswith three computer punch cards per piping element. A pipinganalysis model which can be developed in much less than an hourtoday, could have taken a week to input, verify and run back then.As a result a number of approximation methods were (and stillare) available. Some of these methods include Guided CantileverCharts, Tube Turn, Grinnell, and the formula provided in para.119.7.1. ASCE Manual on Steel construction contains beam for-mulas which form the basis of most formal analysis software,these beam formulas can also be used to approximate results fromformal analysis. There are a lot of warnings and precautions forany of these methods, however many of the same references andwarnings also apply to formal analysis. It now takes more time todocument the acceptability of an approximation method than todevelop a formal model, however without a good understandingof the approximation methods, the user may not have the knowl-edge to recognize when there is an error in the formal analysis.References 14, 15, and 22 provide a number of simplified meth-ods for this purpose.

The user is strongly encouraged to have a basic expectation ofthe results of any formal computer analysis whether from pipinganalysis software, or finite element analysis. These are sometimesreferred to as “sanity checks”, “rules of thumb”, “simplified approx-imation methods”, etc. but regardless of what they are called, it isimportant to understand when the results of the computer analysisare conservative, or when they give you the answer you want to hear. Note the term conservative versus the term correct. It isvery unlikely the analyst could ever calculate an accurate stresson a piping element after it has experienced a few thermal cycles,the residual stresses from fabrication, and tolerances associatedwith construction. The goal is to envelop everything the pipingsystem could possibly experience and make sure it is safe forthose conditions.

35.3.5.4 Basic Assumptions and Requirements This sectionprovides a lot of information on flexibility analysis and assump-tions. Boundary conditions, and many problems encountered inthe field are the result of inaccurate modeling of these conditions.One of the most important conditions is the stiffness of the sup-ports or restraints. Unless provided, most commercial analysissoftware will assume supports, restraints and anchors (usuallyequipment nozzles) are very rigid. This is a good assumption formaximizing the stresses developed in a piping system, but mayresult in a load being shifted to the wrong location because of the relative stiffness of the supports. Additional guidance on calculating movements, separating analysis into smaller simplersubsystems (highly recommended by the author) and means of

PROPRIETARY A

SME


increasing flexibility are covered in this section and also mixed inwith some of the previous sections.

35.3.5.6 Cold Spring Para.119.9 provides an explanation onthe concept and requirements of cold spring. Cold spring is usedmore widely in the Power Piping because of the large diameterhot piping connected to the turbine. It is very difficult to meet theallowable force and moment loading on the turbine, and coldspring was one technique to help reduce the loads. Many client/owner specifications now prohibit the use of cold spring. This isbecause it is extremely difficult to verify the cold spring is cor-rectly installed during the construction, and even more difficult tobe sure it is maintained during maintenance activities throughoutthe life of the plant. Also see para. 119.10 for formulas to be usedin calculating reaction loads when cold spring is used.

35.3.6 Piping SupportPipe supports are obviously an important part of the piping

design. This chapter is relatively straight forward and providesinformation to be considered during the design and support ofpiping systems. In addition to the requirements in this section ofthe code, MSS-SP58, 2002 edition, and the support manufacturesprovide additional information on the design of pipe supports. A point worth highlighting the term support also applies to re-straints. The term restraint is more likely to apply to restraints inthe axial or lateral direction relative to the pipe. These restraintsare important for seismic or wind loading as well as restraintsrequired to control the thermal expansion of the piping. Whererestraints are used to control the thermal expansion of longstraight runs of thermal expansion, the user must make sure loadsfrom friction are added to the loads from the flexibility analysis.While friction can be included in the flexibility analysis, this canbe complicated and it is common practice to calculate frictionalloads separately and add them to the support loads. The mostimportant consideration with friction is it can never help the user.This is probably the best reason not to include it in the pipinganalysis, because the analysis is performed without being sure if itis helping one of the load cases.

35.3.6.1 Anchors and Guides A very brief mention is madeabout Anchors and Guides having to resist loads from both expan-sion and internal pressure. The user must understand the pressurethrusts developed by expansion joints and restraint systems asso-ciated with them. Most expansion joint manufactures provide very good design information on calculating and controlling thispressure thrust as well is information on the allowable move-ments associated with their products. The effect of pressure on arestraint is usually very small, however when expansion joints areused in a system, these can quickly become the dominant load ifnot restrained correctly.

35.3.6.2 Variable and Constant Supports Spring supportsdiscussed in para.120.2.2 are an important part of supporting pip-ing systems when there are significant movements in the verticaldirection. Sometimes very small vertical movements can be sig-nificant if the user is trying to protect equipment from thermalexpansion loads. Other times, a piping system may run verticallyfor long distances. This makes it very difficult to distribute thepiping loads without the use of spring supports. References 14,15, and 22 provide excellent guidance on how to design supportsto meet the requirements in this section.

35.3.7 SystemsThe design section in the Code refers to specific systems, some

of which are covered here. Because ASME B31.1 is specific toPower Piping the systems addressed here are only those typicallyfound in power generating facilities.

35.3.7.1 Boiler External Piping (BEP) Boiler External Pipingas was described in the beginning of this chapter is generally themost critical piping in a power plant. As a result a number ofrequirements and limitations on BEP in general as well as specificrequirements associated with steam, feedwater, blowoff and blow-down, drains, valves and miscellaneous systems are provided inpara. 122.1 through 122.1.7.

35.3.7.1.1 Steam Piping (BEP). Para. 122.1.2 provides spe-cific requirements for the Design Pressure which was used backin para. 104 for the pressure design. This pressure is associatedwith the pressure design and rating of the boiler which makessense because Boiler External Piping is really an extension of theBoiler. Both saturated steam and steam from a superheater areaddressed in these paragraphs.

35.3.7.1.2 Feedwater Piping (BEP). Similar to the steam pip-ing, these paragraphs provide specific requirements for the designpressure of the feedwater piping downstream of the required stopand check valves which form the boundary for Boiler ExternalPiping (BEP). These requirements are specific to the type of boilerand equipment associated with the boiler. These requirements needto be worked with the figures 100.1.2(A.1-A.3) [25].

35.3.7.1.3 Blowoff and Blowdown Piping (BEP). Both ofthese systems are defined specifically in the para. 122.1.4. Thesystems are required for proper operation of the boiler and asso-ciated with high pressure water being released to relatively low pressure where it is expected to flash. Both of these spe-cific systems are connected to the water side of the boiler andhave specific requirements for the design pressure and material requirements.

Blowoff and Blowdown Piping in “Nonboiler External Pipingare covered in para. 122.2.

35.3.7.1.4 Boiler Drains. Not to be confused with Blowoff andBlowdown piping described above, Boiler Drains are not intendedto be operated during normal operation of a Boiler. If they are,they become Blowoff and Blowdown Piping described above.

Boiler drains are intended for start-up and shut down and as aresult the requirements in para. 122.1.5 are associated with therequired number of valves and administrative controls or lockingdevices to be sure they are not operated under normal boiler oper-ating conditions.

35.3.7.1.5 Miscellaneous Systems (BEP). Para. 122.1.6 isintended to capture any other components which are not internalto the boiler, but also do not fit any of the previous systems. Theyare still important however because they form part of the BoilerPressure Boundary.

35.3.7.1.6 Valves and Fittings (BEP). This section identifiestypes of valves and fittings which are required, or prohibited fromthe Boiler External Piping Systems which have just been covered.For the most part, the valves will form the boundary of the BoilerExternal Piping System. In some cases valves in BEP will provide

PROPRIETARY A

SME

35-10 • Chapter 35

isolation and protection between a boiler which might be occu-pied for maintenance and other boilers which are still operating.

35.3.7.2 Blowoff and Blowdown Piping in NonboilerExternal Piping This is a continuation of the requirements in122.1.4, except the blowoff, or blowdown piping downstream ofthe boundary between the Boiler External Piping and the associ-ated valves. Again, these systems are exposed to steam/waterwhich is flashing as it moves to a lower pressure condition andadditional requirements are addressed.

35.3.7.3 Instrument, Control and Sample Piping Instru-mentation piping is covered in para. 122.3 and should be reviewedbecause a frequent misunderstanding instrument piping is notcovered by the Code. If the instrument is in line, or the tubing ispart of the piping system pressure boundary, the instrument pip-ing is included in the scope of the Code. This also applies to theair or hydraulic fluid used to operate valves or control apparatus.

35.3.7.4 Desuperheater Piping Systems Piping associatedwith desuperheaters, attemperators or spray water systems areexposed to the transition between water, saturated steam andsuperheated steam. Each of these have different fluid propertiesand therefore deserve additional design considerations. Para 122.4identifies a number of additional requirements for piping in orpotentially in this transition region.

35.3.7.5 Pressure-Reducing Valves Pressure-reducing valvesform the boundary between high pressure systems and low pres-sure systems when everything is operating normally. Para. 122.5provides design requirements to protect the low pressure side of this boundary for potential failure of the pressure-reducingvalve(s).

35.3.7.6 Piping to Pressure-Relieving Safety Devices PressureRelieving Systems receive special attention because of their impor-tance in maintaining the piping system within the design pressure.The Code has specific requirements in para 122.6 to ensure therelief valves cannot be isolated during the operation of the boiler orpiping system it is there to protect. In addition, the pressure thrustfrom a relief valve can be significant and the effect on the piping toand from the relief valve must be considered in the design.Appendix II provides nonmandatory rules for determining the loadsassociated with relief valve discharge. These rules were developedsome time ago and may not be conservative for supercritical boil-ers. The user should verify discharge loads with the relief valvemanufacture if there is any doubt on what loads to use.

Pressure Relief Valves are designed to ASME BPV CodeSection VIII Div 1 and appropriate sections of ASME BPV CodeSection VIII Div 1 are referenced in para 122.1.7(D).

35.3.7.7 Piping in Flammable, Combustible or Toxic ServiceThe Code identifies additional requirements and restrictions forFlammable, Combustible or Toxic Liquids and Gases. Liquids areaddressed in para. 122.7, gases and toxic liquids are addressed in122.8. Both of these sections require review for any non steam/water services in Code piping.

35.3.7.8 Temporary Piping Systems Temporary piping sys-tems are piping systems which are not considered “Code” piping.They are addressed in para. 122.10 only because they still can beassociated with hazardous conditions and should not be ignored.Recent industrial accidents have resulted in a number of fatalities.

The user is cautioned the Code is a pressure design code, not anoperations code. As such it does not include operating rules orguidance other than Chapter VII which says operate the pipingwithin the design conditions. The venting of gases during opera-tions or start-up can create a number of hazards must be reviewedby competent personnel prior to any such operation.

35.3.7.9 Other Systems A number of other specific systemslike Steam Trap Piping, Exhaust, Pump Suction, Pump Dischargeand District Heating and Steam Distribution Systems also havespecific requirements or warnings and should be reviewed in thesesections.

35.4 MATERIALS

Chapter III of the Code addresses limitations on materials usedfor Code construction. For the most part, the Code provides anextensive list of acceptable materials in Appendix A. Chapter IIIoutlines limitations for some of these materials in specific ser-vices or systems. Appendix A and its organization will bedescribed in more detail later in this chapter. Requirements arealso provided for the use of materials not listed in Appendix A.

Power piping systems generally operate and are designed forhigh temperatures, as a result, the minimum temperature providedin appendix A is limited to –20oF. ASME B31T has also recentlybeen published to provide an additional guidance for lower tem-perature services. While not currently referenced, this standard orASME B31.3 provide additional guidance and requirements ifmaterial toughness is a consideration. Also see reference 16 formore information.

35.5 DIMENSIONAL REQUIREMENTS

Standard components were discussed in paragraph 35.3.3.1with the discussion and Table 35.1 giving examples of how com-ponent standards work together to provide dimensional and pres-sure temperature ratings. Chapter IV, Table 126.1 [25] repeated asTable 35. 2 below provides a list of acceptable standards for Codeconstruction. The user is cautioned while these standards areacceptable they are only acceptable within the limits provided inthe reference standard and in some cases additional limitations ofthe Code. Chapter IV of the code provides requirements/responsi-bilities so the user can qualify unlisted components for Code use.See reference 7 for additional guidance.

35.6 FABRICATION, ASSEMBLY ANDERECTION

35.6.1 Welding, Preheating and Post Weld Heat TreatThis is Chapter V in the Code and it addresses Welding require-

ments and Welding Qualification. Many of the welding require-ments are referenced back to ASME B&PV Code Section IX.Some differences between the various Codes are associated withservice requirements however others have no reason for being different. A significant effort is being made to minimize these dif-ferences and this continues to be an ongoing effort by committeemembers.

35.6.1.1 Welding Procedure Specification (WPS) A WPS is a written welding procedure for making production welds to

PROPRIETARY A

SME


AISC Publication

. . . Manual of Steel Construction Allowable Stress Design

ASCE Standard

ASCE/SEI 7 Minimum Design Loads for Buildings and Other Structures

ASTM Ferrous Material Specifications

Bolts, Nuts, and Studs

A 193/A 193M Alloy-Steel and Stainless Steel Bolting Materials for High-Temperature ServiceA 194/A 194M Carbon and Alloy Steel Nuts for Bolts for High-Pressure and High-Temperature ServiceA 307 Carbon Steel Bolts and Studs, 60,000 psi Tensile StrengthA 320/A 320M Alloy-Steel Bolting Materials for Low-Temperature ServiceA 354 Quenched and Tempered Alloy Steel Bolts, Studs and Other Externally-Threaded FastenersA 437/A 437M Alloy-Steel Turbine-Type Bolting Material Specially Heat Treated for High Temperature ServiceA 449 Quenched and Tempered Steel Bolts and StudsA 453/A 453M High-Temperature Bolting Materials, With Expansion Coefficients Comparable to Austenitic Steels

Castings

A 47/A 47M Ferritic Malleable Iron CastingsA 48/A 48M Gray Iron CastingsA 126 Gray Iron Castings for Valves, Flanges, and Pipe FittingsA 197/A 197M Cupola Malleable IronA 216/A 216M Steel Castings, Carbon Suitable for Fusion Welding for High Temperature ServiceA 217/A 217M Steel Castings, Martensitic Stainless and Alloy, for Pressure-Containing Parts Suitable for High-Temperature ServiceA 278/A 278M Gray Iron Castings for Pressure-Containing Parts for Temperatures Up to 650°F (350°C)A 351/A 351M Steel Castings, Austenitic, for High-Temperature ServiceA 389/A 389M Steel Castings, Alloy, Specially Heat-Treated for Pressure-Containing Parts Suitable for High-Temperature ServiceA 395/A 395M Ferritic Ductile Iron Pressure-Retaining Castings for Use at Elevated TemperaturesA 536 Ductile Iron Castings

Forgings

A 105/A 105M Forgings, Carbon Steel, for Piping ComponentsA 181/A 181M Forgings, Carbon Steel for General Purpose PipingA 182/A 182M Forged or Rolled Alloy-Steel Pipe Flanges, Forged Fittings, and Valves and Parts for High-Temperature ServiceA 336/A 336M Alloy Steel Forgings for Pressure and High-Temperature PartsA 350/A 350M Forgings, Carbon and Low-Alloy Steel, Requiring Notch Toughness Testing for Piping Components

Cast Pipe

A 377 Standard Index of Specifications for Ductile Iron Pressure PipeA 426/A 426M Centrifugally Cast Ferritic Alloy Steel Pipe for High-Temperature ServiceA 451/A 451M Centrifugally Cast Austenitic Steel Pipe for High-Temperature Service

Seamless Pipe and Tube

A 106/A 106M Seamless Carbon Steel Pipe for High-Temperature ServiceA 179/A 179M Seamless Cold-Drawn Low-Carbon Steel Heat-Exchanger and Condenser TubesA 192/A 192M Seamless Carbon Steel Boiler Tubes for High-Pressure ServiceA 199 Seamless Cold-Drawn Intermediate Alloy-Steel Heat-Exchanger and Condenser TubesA 210/A 210M Seamless Medium-Carbon Steel Boiler and Superheater TubesA 213/A 213M Seamless Ferritic and Austenitic Alloy-Steel Boiler, Superheater, and Heat-Exchanger TubesA 335/A 335M Seamless Ferritic Alloy Steel Pipe for High-Temperature ServiceA 369/A 369M Carbon and Ferritic Alloy Steel Forged and Bored Pipe for High-Temperature ServiceA 376/A 376M Seamless Austenitic Steel Pipe for High-Temperature Central-Station Service

TABLE 35.2 SPECIFICATIONS AND STANDARDS (Source: ASME B31.1, 2010 Table 126.1 [25])

PROPRIETARY A

SME

35-12 • Chapter 35

ASTM Ferrous Material Specifications (Cont’d)

Seamless and Welded Pipe and Tube

A 53/A 53M Pipe, Steel, Black and Hot-Dipped, Zinc-Coated Welded and SeamlessA 268/A 268M Seamless and Welded Ferritic and Martensitic Stainless Steel Tubing for General ServiceA 312/A 312 Seamless and Welded Austenitic Stainless Steel PipeA 333/A 333M Seamless and Welded Steel Pipe for Low-Temperature ServiceA 450/A 450M General Requirements for Carbon, Ferritic Alloy, and Austenitic Alloy Steel TubesA 530/A 530M General Requirements for Specialized Carbon and Alloy Steel PipeA 714 High-Strength Low-Alloy Welded and Seamless Steel PipeA 789/A 789M Standard Specification for Seamless and Welded Ferritic/Austenitic Stainless Steel Tubing for General ServiceA 790/A 790M Standard Specification for Seamless and Welded Ferritic/Austenitic Stainless Steel Pipe

Welded Pipe and Tube

A 134 Pipe, Steel, Electric-Fusion (Arc)-Welded (Sizes NPS 16 and Over)A 135/A 135M Electric-Resistance-Welded Steel PipeA 139/A 139M Electric-Fusion (Arc)-Welded Steel Pipe (NPS 4 in. and Over)A 178/A 178M Electric-Resistance-Welded Carbon and Carbon-Manganese Steel Boiler and Superheater TubesA 214/A 214M Electric-Resistance-Welded Carbon Steel Heat-Exchanger and Condenser TubesA 249/A 249M Welded Austenitic Steel Boiler, Superheater, Heat-Exchanger, and Condenser TubesA 254 Copper Brazed Steel TubingA 358/A 358M Electric-Fusion-Welded Austenitic Chromium-Nickel Alloy Steel Pipe for High-Temperature ServiceA 409/A 409M Welded Large Diameter Austenitic Steel Pipe for Corrosive or High-Temperature ServiceA 587 Electric-Resistance-Welded Low-Carbon Steel Pipe for the Chemical IndustryA 671 Electric-Fusion-Welded Steel Pipe for Atmospheric and Lower TemperaturesA 672 Electric-Fusion-Welded Steel Pipe for High-Pressure Service at Moderate TemperaturesA 691 Carbon and Alloy Steel Pipe, Electric-Fusion-Welded for High-Pressure Service at High TemperaturesA 928/A 928M Ferritic/Austenitic (Duplex) Stainless Steel Pipe Electric Fusion Welded with Addition of Filler Metal

Fittings

A 234/A 234M Piping Fittings of Wrought Carbon Steel and Alloy Steel for Moderate and Elevated Temperature ServicesA 403/A 403M Wrought Austenitic Stainless Steel Piping FittingsA 420/A 420M Piping Fittings of Wrought Carbon Steel and Alloy Steel for Low-Temperature ServiceA 815/A 815M Wrought Ferritic, Ferritic/Austenitic, and Martensitic Stainless Steel Piping Fittings

Plate, Sheet, and Strip

A 240/A 240M Heat-Resistant Chromium and Chromium-Nickel Stainless Steel Plate Sheet and Strip for Pressure VesselsA 283/A 283M Low and Intermediate Tensile Strength Carbon Steel PlatesA 285/A 285M Pressure Vessel Plates, Carbon Steel, Low- and Intermediate-Tensile StrengthA 299/A 299M Pressure Vessel Plates, Carbon Steel, Manganese-SiliconA 387/A 387M Pressure Vessel Plates, Alloy Steel, Chromium-MolybdenumA 515/A 515M Pressure Vessel Plates, Carbon Steel for Intermediate- and Higher-Temperature ServiceA 516/A 516M Pressure Vessel Plates, Carbon Steel, for Moderate- and Lower-Temperature Service

Rods, Bars, and Shapes

A 276/A 276M Stainless Steel Bars and ShapesA 322 Steel Bars, Alloy, Standard GradesA 479/A 479M Stainless Steel Bars and Shapes for Use in Boilers and Other Pressure VesselsA 564/A 564M Hot-Rolled and Cold-Finished Age-Hardening Stainless Steel Bars and ShapesA 575 Steel Bars, Carbon, Merchant Quality, M-GradesA 576 Steel Bars, Carbon, Hot-Wrought, Special Quality

Structural Components

A 36/A 36M Structural SteelA 125 Steel Springs, Helical, Heat TreatedA 229/A 229M Steel Wire, Oil-Tempered for Mechanical SpringsA 242/A 242M High-Strength Low Alloy Structural SteelA 992/A 992M Structural Shapes

TABLE 35.2 (CONTINUED)

PROPRIETARY A

SME


ASTM Nonferrous Material Specifications

Castings

B 26/B 26M Aluminum-Alloy Sand CastingsB 61 Steam or Valve Bronze CastingsB 62 Composition Bronze or Ounce Metal CastingsB 108 Aluminum-Alloy Permanent Mold CastingsB 148 Aluminum-Bronze Sand CastingsB 367 Titanium and Titanium Alloy CastingsB 584 Copper Alloy Sand Castings for General Applications

Forgings

B 247 & B 247M Aluminum and Aluminum-Alloy Die, Hand, and Rolled Ring ForgingsB 283 Copper and Copper-Alloy Die Forgings (Hot Pressed)B 381 Titanium and Titanium Alloy ForgingsB 462 Forged or Rolled UNS N06030, N06022, N06035, N06200, N06059, N06686, N08020, N08024, N08026, N08367,

N10276, N10665, N10675, N10629, N08031, N06045, N06025, and R20033 Alloy Pipe Flanges, Forged Fittings,and Valves and Parts for Corrosive High-Temperature Service

B 564 Nickel Alloy Forgings

Seamless Pipe and Tube

B 42 Seamless Copper Pipe, Standard SizesB 43 Seamless Red Brass Pipe, Standard SizesB 68 & B 68M Seamless Copper Tube, Bright AnnealedB 75 Seamless Copper TubeB 88 & B 88M Seamless Copper Water TubeB 111 & B 111M Copper and Copper-Alloy Seamless Condenser Tubes and Ferrule StockB 161 Nickel Seamless Pipe and TubeB 163 Seamless Nickel and Nickel-Alloy Condenser and Heat-Exchanger TubesB 165 Nickel-Copper Alloy (UNS N04400) Seamless Pipe and TubeB 167 Nickel-Chromium-Iron Alloy (UNS N06600, N06601, N06603, N06690, N06693, N06025, and N06645) and Nickel-

Chromium-Cobalt-Molybdenum Alloy (UNS N06617) Seamless Pipe and TubeB 210 & B 210M Aluminum Alloy Drawn Seamless TubesB 234 & B 234M Aluminum and Aluminum-Alloy Drawn Seamless Tubes for Condensers and Heat ExchangersB 241/B 241M Aluminum-Alloy Seamless Pipe and Seamless Extruded TubeB 251 & B 251M General Requirements for Wrought Seamless Copper and Copper-Alloy TubeB 280 Seamless Copper Tube for Air Conditioning and Refrigeration Field ServiceB 302 Threadless Copper Pipe, Standard SizesB 315 Seamless Copper Alloy Pipe and TubeB 407 Nickel-Iron-Chromium Alloy Seamless Pipe and TubeB 423 Nickel-Iron-Chromium-Molybdenum-Copper Alloy (UNS N08825 and N08821) Seamless Pipe and TubeB 466 / B 466M Seamless Copper-Nickel Pipe and TubeB 622 Seamless Nickel and Nickel-Cobalt Alloy Pipe and TubeB 677 UNS N08904, UNS N08925, and UNS N08926 Seamless Pipe and TubeB 690 Iron-Nickel-Chromium-Molybdenum Alloys (UNS N08366 and UNS N08367) Seamless Pipe and TubeB 729 Seamless UNS N08020, UNS N08026, and UNS N08024 Nickel-Alloy Pipe and TubeB 861 Titanium and Titanium Alloy Seamless Pipe

Seamless and Welded Pipe and Tube

B 338 Seamless and Welded Titanium and Titanium Alloy Tubes for Condensers and Heat ExchangersB 444 Nickel-Chromium-Molybdenum-Columbium Alloy (UNS N06625) Plate, Sheet, and Strip

Welded Pipe and Tube

B 464 Welded (UNS N08020, N08024, N08026 Alloy) PipeB 467 Welded Copper-Nickel PipeB 468 Welded (UNS N08020, N08024, N08026) Alloy TubesB 546 Electric Fusion-Welded Ni-Cr-Co-Mo Alloy (UNS N06617), Ni-Fe-Cr-Si Alloys (UNS N08330 and UNS N08332), Ni-Cr-Fe-Al

Alloy (UNS N06603), Ni-Cr-Fe Alloy (UNS N06025), and Ni-Cr-Fe-Si Alloy (UNS N06045) Pipe


PROPRIETARY A

SME

35-14 • Chapter 35

ASTM Nonferrous Material Specifications (Cont’d)

Welded Pipe and Tube (Cont’d)

B 547/B 547M Aluminum and Aluminum-Alloy Formed and Arc-Welded Round TubeB 608 Welded Copper-Alloy PipeB 619 Welded Nickel and Nickel-Cobalt Alloy PipeB 626 Welded Nickel and Nickel-Cobalt Alloy TubeB 673 UNS N08904, UNS N08925, and UNS N08926 Welded PipeB 674 UNS N08904, UNS N08925, and UNS N08926 Welded TubeB 675 UNS N08367 Welded PipeB 676 UNS N08367 Welded TubeB 704 Welded UNS N06625 and N08825 Alloy TubesB 705 Nickel-Alloy (UNS N06625 and N08825) Welded PipeB 804 UNS N08367 and UNS N08926 Welded PipeB 862 Titanium and Titanium Alloy Welded Pipe

Fittings

B 361 Factory-Made Wrought Aluminum and Aluminum-Alloy Welding FittingsB 366 Factory-Made Wrought Nickel and Nickel Alloy Fittings

Plate, Sheet, and Strip

B 168 Nickel-Chromium-Iron Alloys (UNS N06600, N06601, N06603, N06690, N06693, N06025, N06045) and Nickel-Chromium-Cobalt-Molybdenum Alloy (UNS N06617) Plate, Sheet, and Strip

B 171 Copper-Alloy Plate and Sheet for Pressure Vessels, Condensers, and Heat ExchangersB 209/B 209M Aluminum and Aluminum-Alloy Sheet and PlateB 265 Titanium and Titanium-Alloy Strip, Sheet, and PlateB 409 Nickel-Iron-Chromium Alloy Plate, Sheet, and StripB 424 Ni-Fe-Cr-Mo-Cu Alloy (UNS N08825 and N08221) Plate, Sheet, and StripB 435 UNS N06002, UNS N06230, UNS N12160, and UNS R30556 Plate, Sheet, and StripB 443 Nickel-Chromium-Molybdenum-Columbium Alloy (UNS N06625) Plate, Sheet, and StripB 463 UNS N08020, UNS N08026, and UNS N08024 Alloy Plate, Sheet, and StripB 625 UNS N08904, UNS N08925, UNS N08031, UNS N08932, UNS N08926, and UNS R20033 Plate, Sheet, and StripB 688 Chromium-Nickel-Molybdenum-Iron (UNS N08366 and UNS N08367) Plate, Sheet, and Strip

Rods, Bars, and Shapes

B 150 & B 150M Aluminum Bronze Rod, Bar, and ShapesB 151/B 151M Copper-Nickel-Zinc Alloy (Nickel Silver) and Copper-Nickel Rod and BarB 166 Nickel-Chromium-Iron Alloys (UNS N06600, N06601, N06603, N06690, N06693, N06025, and N06045) and

Nickel-Chromium-Cobalt-Molybdenum Alloy (UNS N06617) Rod, Bar, and WireB 221 & B 221M Aluminum and Aluminum Alloy Extruded Bars, Rods, Wire, Profiles, and TubesB 348 Titanium and Titanium Alloy Bars and BilletsB 408 Nickel-Iron-Chromium Alloy Rod and BarB 425 Ni-Fe-Cr-Mo-Cu Alloy (UNS N08825 and N08221) Rod and BarB 446 Nickel-Chromium Molybdenum-Columbium Alloy (UNS N06625) Rod and BarB 473 UNS N08020, UNS N08024, and UNS N08026 Nickel Alloy Bar and WireB 572 UNS N06002, UNS N06230, UNS N12160, and UNS R30556 RodB 649 Ni-Fe-Cr-Mo-Cu Low-Carbon Alloy (N08904), Ni-Fe-Cr-Mo-Cu-N Low-Carbon Alloys (UNS N08925, UNS N08031, and

UNS N08926), and Cr-Ni-Fe-N Low-Carbon Alloy (UNS R20033) Bar and WireB 691 Iron-Nickel-Chromium-Molybdenum Alloys (UNS N08366 and UNS N08367) Rod, Bar, and Wire

Solder

B 32 Solder MetalB 828 Standard Practice for Making Capillary Joints by Soldering of Copper and Copper Alloy Tube and Fittings


PROPRIETARY A

SME


ASTM Standard Test Methods

D 323 Standard Test Method for Vapor Pressure of Petroleum Products (Reid Method)E 94 Standard Guide for Radiographic ExaminationE 125 Standard Reference Photographs for Magnetic Particle Indications on Ferrous CastingsE 186 Standard Reference Radiographs for Heavy-Walled (2 to 41⁄2-in. [51 to 114-mm] Steel CastingsE 280 Standard Reference Radiographs for Heavy-Walled (41⁄2 to 12-in. [114 to 305-mm] Steel CastingsE 446 Standard Reference Radiographs for Steel Castings Up to 2 in. [51 mm] in Thickness

API Specification

Seamless and Welded Pipe

5L Line Pipe

American National Standard

Z223.1 National Fuel Gas Code (ANSI/NFPA 54)

MSS Standard Practices

SP-6 Standard Finishes for Contact Faces of Pipe Flanges and Connecting-End Flanges of Valves and FittingsSP-9 Spot-Facing for Bronze, Iron and Steel FlangesSP-25 Standard Marking System for Valves, Fittings, Flanges and UnionsSP-42 [Note (1)] Class 150 Corrosion Resistant Gate, Globe, Angle and Check Valves With Flanged and Buttweld EndsSP-43 Wrought and Fabricated Butt-Welding Fittings for Low Pressure, Corrosion Resistant ApplicationsSP-45 Bypass & Drain ConnectionSP-51 Class 150 LW Corrosion Resistant Cast Flanges and Flanged FittingsSP-53 Quality Standard for Steel Castings and Forgings for Valves, Flanges, and Fittings and Other Piping Components —

Magnetic Particle Examination MethodSP-54 Quality Standard for Steel Castings for Valves, Flanges, and Fittings and Other Piping Components — Radiographic

Examination MethodSP-55 Quality Standard for Steel Castings for Valves, Flanges, and Fittings and Other Piping Components — Visual Method for

Evaluation of Surface IrregularitiesSP-58 Pipe Hangers and Supports — Materials, Design, and ManufactureSP-61 Pressure Testing of Steel ValvesSP-67 [Note (1)] Butterfly ValvesSP-68 High Pressure Butterfly Valves with Offset DesignSP-69 Pipe Hangers and Supports — Selection and ApplicationSP-75 Specification for High Test Wrought Butt-Welding FittingsSP-79 Socket Welding Reducer InsertsSP-80 Bronze Gate, Globe, Angle and Check ValvesSP-83 Class 3000 Steel Pipe Unions, Socket Welding and ThreadedSP-88 Diaphragm ValvesSP-89 Pipe Hangers and Supports — Fabrication and Installation PracticesSP-93 Quality Standard for Steel Castings and Forgings for Valves, Flanges, and Fittings and Other Piping Components —

Liquid Penetrant Examination MethodSP-94 Quality Standard for Ferritic and Martensitic Steel Castings for Valves, Flanges, and Fittings and Other Piping

Components — Ultrasonic Examination MethodSP-95 Swaged Nipples and Bull PlugsSP-97 Integrally Reinforced Forged Branch Outlet Fittings — Socket Welding, Threaded and Buttwelding EndsSP-105 Instrument Valves for Code ApplicationsSP-106 Cast Copper Alloy Flanges and Flanged Fittings, Class 125, 150, and 300


PROPRIETARY A

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35-16 • Chapter 35

ASME Codes & Standards

. . . ASME Boiler and Pressure Vessel CodeB1.1 Unified Inch Screw ThreadsB1.13M Metric Screw Threads — M ProfileB1.20.1 Pipe Threads, General Purpose (Inch)B1.20.3 Dryseal Pipe Threads (Inch)B16.1 Cast Iron Pipe Flanges and Flanged Fittings — 25, 125, 250 & 800 ClassesB16.3 Malleable Iron Threaded FittingsB16.4 Gray Iron Threaded FittingsB16.5 Pipe Flanges and Flanged FittingsB16.9 Factory-Made Wrought Buttwelding FittingsB16.10 Face-to-Face and End-to-End Dimensions of ValvesB16.11 Forged Fittings, Socket-Welding and ThreadedB16.14 Ferrous Pipe Plugs, Bushings, and Locknuts With Pipe ThreadsB16.15 Cast Bronze Threaded Fittings, Classes 125 and 250B16.18 Cast Copper Alloy Solder-Joint Pressure FittingsB16.20 Metallic Gaskets for Pipe Flanges — Ring Joint, Spiral Wound, and JacketedB16.21 Nonmetallic Flat Gaskets for Pipe FlangesB16.22 Wrought Copper and Copper Alloy Solder Joint Pressure FittingsB16.24 Cast Copper Alloy Pipe Flanges and Flanged Fittings — Class 150, 300, 400, 600, 900, 1500, and 2500B16.25 Butt Welding EndsB16.34 Valves — Flanged, Threaded, and Welding EndB16.42 Ductile Iron Pipe Flanges and Flanged Fittings — Classes 150 and 300B16.47 Large Diameter Steel FlangesB16.48 Steel Line BlanksB16.50 Wrought Copper and Copper Alloy Braze-Joint Pressure FittingsB18.2.1 Square and Hex Bolts and Screws — Inch SeriesB18.2.2 Square and Hex Nuts (Inch Series)B18.2.3.5M Metric Hex BoltsB18.2.3.6M Metric Heavy Hex BoltsB18.2.4.6M Hex Nuts, Heavy, MetricB18.21.1 Lock Washers (Inch Series)B18.22M Washers, Metric PlainB18.22.1 [Note (2)] Plain WashersB31.3 Process PipingB31.4 Pipeline Transportation Systems for Liquid Hydrocarbons and Other LiquidsB31.8 Gas Transmission and Distribution Piping SystemsB36.10M Welded and Seamless Wrought Steel PipeB36.19M Stainless Steel PipeTDP-1 Recommended Practices for the Prevention of Water Damage to Steam Turbines Used for Electric Power Generation —

Fossil Fueled Plants

AWS Specifications

A3.0 Standard Welding Terms and DefinitionsD10.10 Recommended Practices for Local Heating of Welds in Piping and TubingQC1 Qualification and Certification of Welding Inspectors

AWWA and ANSI/AWWA Standards

C110/A21.10 Ductile-Iron and Gray-Iron Fittings, 3 in. Through 48 in. (76 mm Through 1200 mm), for Water and Other LiquidsC111/A21.11 Rubber-Gasket Joints for Ductile-Iron Pressure Pipe and FittingsC115/A21.15 Flanged Ductile-Iron Pipe With Threaded FlangesC150/A21.50 Thickness Design of Ductile-Iron PipeC151/A21.51 Ductile-Iron Pipe, Centrifugally Cast, for WaterC153/A21.53 Ductile-Iron Compact Fittings, 3 in. Through 24 in. (76 mm Through 610 mm) and 54 in. Through 64 in. (1,400 mm

Through 1,600 mm), for Water Service


PROPRIETARY A

SME


AWWA and ANSI/AWWA Standards (Cont’d)

C200 Steel Water Pipe—6 in. (150 mm) and LargerC207 Steel Pipe Flanges for Waterworks Service—Sizes 4 in. Through 144 in. (100 mm Through 3,600 mm)C208 Dimensions for Fabricated Steel Water Pipe FittingsC300 Reinforced Concrete Pressure Pipe, Steel-Cylinder Type, for Water and Other Liquids (Includes Addendum C300a-93.)C301 Prestressed Concrete Pressure Pipe, Steel-Cylinder Type, for Water and Other LiquidsC302 Reinforced Concrete Pressure Pipe, Noncylinder Type, for Water and Other LiquidsC304 Design of Prestressed Concrete Cylinder PipeC500 Metal-Seated Gate Valves for Water Supply ServiceC504 [Note (1)] Rubber Seated Butterfly ValvesC509 Resilient-Seated Gate Valves for Water Supply ServiceC600 Installation of Ductile-Iron Water Mains and Their AppurtenancesC606 Grooved and Shouldered Joints

National Fire Codes

NFPA 54/ANSI National Fuel Gas CodeZ223.1

NFPA 85 Boiler and Combustion Systems Hazards CodeNFPA 1963 Standard for Fire Hose Connections

PFI Standards

ES-16 Access Holes and Plugs for Radiographic Inspection of Pipe WeldsES-24 Pipe Bending Methods, Tolerances, Process and Material Requirements

FCI Standard

79-1 Proof of Pressure Ratings for Pressure Regulators

GENERAL NOTES:(a) For boiler external piping application, see para. 123.2.2.(b) For all other piping, materials conforming to an ASME SA or SB specification may be used interchangeably with material specified to an

ASTM A or B specification of the same number listed in Table 126.1.(c) The approved year of issue of the specifications and standards is not given in this Table. This information is given in Appendix F of

this Code.(d) The addresses and phone numbers of organizations whose specifications and standards are listed in this Table are given at the end of

Appendix F.

NOTES:(1) See para. 107.1(D) for valve stem retention requirements.(2) ANSI B18.22.1 is nonmetric.


specified requirements. The WPS or other document is used tocapture the essential variables of a welding procedure which willbe qualified by destructive testing, then provide direction to thewelder or welding operator to production welds have comparableproperties.

Procedure Qualification Record(s) (PQR) provide documenta-tion of the testing required to qualify a procedure. The ASMEBoiler and Pressure Vessel Code Section IX, QW-482, 483 and484 give suggested formats for Welding Procedure Specifications(WPS), Procedure Qualification Records (PQR) and Welder Per-formance Qualifications (WPQ).

35.6.1.2 Welder Performance Qualification The manufactureror contractor is responsible for conducting tests to qualify weldersand welding operators in accordance with qualified welding proce-dure specifications. The purpose of welder and welding operatorqualification tests is to ensure that the welder(s) and welding oper-ator(s) following the procedures are capable of developing theminimum requirements specified for an acceptable weldment. Per-

formance qualification tests are intended to determine the ability of welders and welding operators to make sound welds.

35.6.2 PreheatingPreheating requirements are provided in para. 131 of the Code.

Preheating is used, along with heat treatment, to minimize thedetrimental effects of high temperature and severe thermal gradi-ents in welding and to drive out hydrogen that could cause weldcracking, and improve metallurgical properties. The effect of re-ducing hydrogen cracking is accomplished by a variety of factors,including driving off moisture, reducing the cooling rate, and in-creasing the rate of hydrogen diffusion in the material.

35.6.3 Heat TreatmentPost–weld heat treatment is performed to temper the weldment,

relax residual stresses, and remove hydrogen. The consequentialbenefits are avoidance of hydrogen-induced cracking and improvedductility, toughness, corrosion resistance, and dimensional stability.

PROPRIETARY A

SME

35-18 • Chapter 35

Heat treatment requirements are provided in para. 132 of ASMEB31.1. The Code requires heat treatment after certain welding,bending, and forming operations. Specific requirements for post-weld heat treatment are provided in Table 132. [25].

35.6.3.1 Governing Thickness for Heat Treatment Whenusing Table 132 [25], the thickness to be used is generally thethicker of the two components, measured at the joint, that arebeing joined by welding. For example, if a pipe is welded to aheavier wall valve, but the valve thickness is tapered to the pipethickness at the welded joint, the governing thickness will be thegreater of the valve thickness at the end of the taper at the weldjoint (presumably the nominal pipe wall thickness) or the pipethickness. Para. 132.4 provides a number of very specific rules fordetermining the “nominal thickness” to be used with Table 132[25] and should be studied carefully when determining therequirements for heat treatment.

35.6.4 Pipe BendsPipe may be hot or cold bent (Reference Para. 129.1, 102.4.5 &

104.2.1). The thickness after bending must comply with thedesign requirements. The Code also references PFI ES-24 (PipeFabrication Institute) [25] for additional requirements on pipebending however this comes with the requirement for the pur-chaser and fabricator to involve the designer if stated manufactur-ing limits are exceeded.

35.6.5 Brazing and SolderingBrazing procedures, brazers, and brazing operators are required

to be qualified in accordance with ASME B&PV Code, SectionIX. Solderers are required to follow the procedures in ASTM B828, Standard Practice for Making Capillary Joints by solderingof Copper and Copper Alloy Tube and Fittings. Aside from theserequirements, general good practice requirements for brazing andsoldering are specified in para. 128 of the Code.

35.6.6 Welded Joint DetailsWelded joint details, including socket weld joints, socket weld

and slip-on flanges, and branch connections are provided inChapter V. Standard details for slip-on and socket welding flangeattachment welds are provided in Fig. 127.4.4(B).

A couple of points worth noting are the fillet weld size, which is1.4 times the nominal pipe wall thickness (or the thickness of thehub, whichever is less), and the small gap shown between theflanges face and the toe of the inside fillet for slip-on flanges. Thesmall gap is intended to avoid damage to the flange face due towelding. It indicates a gap, but there is no specific limit. This differsfrom Section VIII, Division 1 [33], which specify the gap to be .”

The question arose as to whether a specific limit to the gap be-tween the fillet weld and flange face was appropriate. Studies, includ-ing finite element analysis and earlier Markl fatigue testing, indicatedthat it essentially did not matter how much the pipe was inserted intothe flange. Insertion by an amount equal to the hub height was opti-mal for fatigue life, but there was not a significant difference. To min-imize future confusion, inclusion of minimum insertion depth hasbeen recommended and may be specified in a future edition ofB31.1. Reference 12 provides a much more detailed evaluation on fillet welds and insertion depth effect on a joint.

The required fillet weld size for socket welds other than socketweld flange is specified in Fig. 127.4.4(C). An issue with this figure which has caused considerable controversy is the 1/16” (2 mm) approx. gap before welding. This is a requirement for a

14

gap before welding, so that weld shrinkage will be less likely tocause small cracks in the root of the fillet weld. The user can finda number of interpretations on this subject on the ASME web site,but the fillet weld should be acceptable if it did not crack. There isno Code requirement for a gap after it has been welded.

35.7 INSPECTION, EXAMINATION, ANDTESTING

35.7.1 InspectionThis can be thought of as more of a Quality assurance function.

The owner’s Inspector oversees the work performed by the exam-iner. It is the Inspector’s responsibility to verify that all the requiredexaminations have been completed and to inspect the piping to theextent necessary to be satisfied that it complies with all of theapplicable examination requirements of the Code and of the engi-neering design. Note that the process of inspection does not relievethe manufacturer, fabricator, or erector of their responsibilities forcomplying with the Code. The Authorized Inspector is also re-quired to be qualified to perform the work, see para. 136.1.4 forNonboiler external piping and 136.2 for Boiler External Piping.

The owner’s Inspector may be an employee of the owner, or anemployee of an engineering or scientific organization, or of a rec-ognized insurance or inspection company, acting as the owner’sagent. Some limits apply to avoid a conflict of interest for theinspector(s).

35.7.2 ExaminationOverview of Examination Requirements.ASME B31.1 requires that examination of the piping be per-

formed by the piping manufacturer, fabricator, and/or erector as aquality control function. These examinations include a number ofdifferent methods based on the type of material or fabrication.

The examiner is required to be an individual that is qualified toperform the examination work. The qualification requirements areprovided in para. 136.3.2, or as an alternate, ASME Boiler andPressure Vessel Code, Section V, Article 1 may be used. Therequired degree of examination and the acceptance criteria for theexaminations are provided in Chapter VI of ASME B31.1.

35.7.2.1 Visual Examination Visual examination (VT) meansusing the unaided eye (except for corrective lenses) to inspect theexterior and readily accessible internal surface areas of pipingassemblies or components. It does not include nor require remoteexamination such as by the use of boroscopes. Visual examinationis used to check materials and components for conformance tospecifications and freedom from defects; fabrication includingwelds; assembly of threaded, bolted, and other joints; piping dur-ing erection; and piping after erection. Note that VT includes theverification that the design and WPS requirements are being met,so VT is not just looking at the weld.

35.7.2.2 Magnetic Particle Examination Magnetic-particleexamination (MT) employs either electric coils wound around thepart or prods to create a magnetic field. A magnetic powder isapplied to the surface and defects are revealed by patterns that thepowder forms in response to the magnetic field disturbancescaused by defects. This technique reveals surface and shallowsubsurface defects. As such, it can provide more information thanliquid-penetrant examination. However, its use is limited to mag-netic materials.

PROPRIETARY A

SME


35.7.2.3 Liquid-Penetrant Examination Liquid-penetrantexamination (PT) means detecting surface defects by spreading aliquid dye penetrant on the surface, removing the dye after suffi-cient time has passed for the dye to penetrate into any surfacedefect, and applying a thin coat of developer to the surface, whichdraws the dye from defects. The defects are observable by thecontrast between the color of the dye penetrant and the color ofthe developer. Liquid-penetrant examination is used for the detec-tion of surface defects. It is used in the examination of socketwelds, branch connections welds that cannot be radiographed;including structural examination of attachment welds.

35.7.2.4 Radiography Radiographic examination (RT) meansusing x-ray or gammaray radiation to produce a picture of thesubject part, including subsurface features, on radiographic filmfor subsequent interpretation. It is a volumetric examination pro-cedure that provides a means of detecting defects that are notobservable on the surface of the material. Requirements for radi-ographic examination of welds are provided in ASME B&PVCode Section V, Article 2.

35.7.2.5 Ultrasonic Examination Ultrasonic examination (UT)means detecting defects using high-frequency sound impulses. Thedefects are detected by the reflection of sound waves from them.Ultrasonic examination is also a volumetric examination methodthat can be used to detect subsurface defects. It can be used as analternative to radiography for weld examination. The requirementsfor ultrasonic examination of welds are provided in ASME B&PVCode Section V, Article 4, with an alternative for basic calibrationblocks provided in para. 136.4.6 of ASME B31.1.

35.7.2.6 Required Examination The required examinationdepends on the pressure and temperature design conditions. Table136.4 [25] provides requirements for nondestructive examinationbased on temperatures over 750oF (400oC), temperatures between350oF (175oC) and 750oF (400oC), and All Others. The intermedi-ate temperature range only applies if the pressure is also over1,025 psig (7,100 kPa).

35.7.3 Testing

35.7.3.1 Pressure Testing - Overview of Pressure TestRequirements ASME B31.1 requires leak testing of all pipingsystems with the exception of lines open to atmosphere. The various options for leak testing are noted below. The hydrotest isthe primary method, but there are a number of places where ahydrotest is not practical and the other tests can be used withinthe limits provided in this section of the Code.

(1) hydrostatic test,(2) pneumatic test,(3) mass-spectrometer and halide testing,(4) initial service leak test.

The leak test is required to be conducted after any heat treat-ment has been completed.

35.7.3.2 Hydrostatic Test A hydrostatic test is the safest test,so it is conducted at a higher pressure, this has beneficial effectssuch as crack blunting and warm prestressing. These reduce therisk of crack growth and brittle fracture after the hydrotest when

the pipe is placed in service. The test is generally conducted at apressure of 1.5 times the design.

35.7.3.3 Pneumatic Test A pneumatic test is more hazardousdue to the amount of stored energy in the compressed gas. A rup-ture could result in an explosive release of this energy. It is alsomore difficult to locate leaks associated with a pneumatic leaktest. Code rules permit the reduction of test pressure while thewelds are being examined.

35.7.3.4 Mass-Spectrometer and Halide Testing The ownermay specify testing methods which have greater sensitivity thancan be obtained by either a hydrostatic nor pneumatic leak test.Paragraph 137.6 of the Code has the requirements associated withthe use of a more sensitive leak test.

35.7.3.5 Initial Service Leak Test When specified by theowner, ASME B31.1 para. 137.7 permits an initial service leaktest in lieu of other leak tests such as hydrostatic or pneumatic. Inthis test, the system is pressurized with the process fluid and thejoints are inspected for leaks. Initial service leak tests are notapplicable to Boiler External Piping.

35.8 OPERATIONS AND MAINTENANCE

As noted in the introduction, ASME B31.1 has recently addedChapter VII which covers maintenance of Covered PipingSystems which are defined as follows:

covered piping systems (CPS): piping systems on which con-dition assessments are to be conducted. As a minimum forelectric power generating stations, the CPS systems are toinclude NPS 4 and larger of the main steam, hot reheatsteam, cold reheat steam, and boiler feedwater piping sys-tems. In addition to the above, CPS also includes NPS 4 andlarger piping in other systems that operate above 750°F(400°C) or above 1,025 psi (7 100 kPa). The OperatingCompany may, in its judgment, include other piping systemsdetermined to be hazardous by an engineering evaluation ofprobability and consequences of failure.

This is a short chapter which makes many of the recommenda-tions in non-mandatory Appendix V requirements. While it doesnot affect design directly, it should be considered during thedesign phase to be sure the required documentation is avail-able for evaluation of the piping systems and supports duringoperations. The title is also a little misleading, because it does not contain any operating requirements beyond operating within de-sign, only maintenance and assessment of degradation to piping systems.

35.9 APPENDICES IN THE CODE

A number of appendices are included in the Code as listedbelow with a brief description of each. Mandatory Appendices areidentified by letters, Nonmandatory Appendices are provided foradditional guidance and identified by roman numerals.

PROPRIETARY A

SME

35-20 • Chapter 35

35.9.1 Mandatory Appendix AAllowable Stresses and Quality Factors forMetallic Piping Bolting Materials [25]

Table A-1, Carbon Steel Table A-2, Low and Intermediate Alloy SteelTable A-3, Stainless SteelsTable A-4, Nickel and High Nickel AlloysTable A-5, Cast IronTable A-6, Copper and Copper AlloysTable A-7, Aluminum and Aluminum AlloysTable A-8, Temperatures 1,200°F and AboveTable A-9, Titanium and Titanium AlloysTable A-10, Bolts, Nuts, and Studs

The allowable stress tables provide allowable stresses for mate-rials which are “listed” in the Code these are currently in USCustomary Units. The tables are organized by material type andwithin those types are component types like Pipe and Tubes,Forgings and Fittings, and Plates and Sheets, Castings, etc.

Along with allowable stress at temperature, these tables pro-vide a lot of other important information including “P numbers for Welding, warning notes, Specified Minimum Yield, TensileStrengths and Weld or Casting Quality Factor. The important partof using these tables is making sure the user is familiar with all ofthe information provided and the notes associated with the material.

35.9.2 Mandatory Appendix B Thermal Expansion Data

These tables provide US Customary and SI units for thermalexpansion data required to evaluate the piping for displacementloads. The appendix is listed as a mandatory appendix, howevernote 1 indicates the data is provided for information only and notimplied the materials are suitable for all the temperature rangesshown.

Table B-1, Thermal Expansion Data [25]Table B-1 (SI), Thermal Expansion Data [25]

35.9.3 Mandatory Appendix CModuli of Elasticity

This appendix provides physical properties required for theanalysis of piping systems. The appendix is listed as a mandatoryappendix, however note 1 indicates the data is provided for infor-mation only and not implied the materials are suitable for all thetemperature ranges shown.

Table C-1, Moduli of Elasticity for Ferrous Material [25]Table C-1 (SI), Moduli of Elasticity for Ferrous Material [25]Table C-2, Moduli of Elasticity for Nonferrous Material [25]Table C-2 (SI), Moduli of Elasticity for Nonferrous Material

[25]

35.9.4 Mandatory Appendix D Flexibility and Stress Intensification Factors

As discussed in 35.3.5.2 and several references, most of thestress intensification factors provided in this appendix were devel-oped from fatigue testing more than 50 years ago. Recent researchon these factors will hopefully be available in ASME B31J [31] in the future. Until then, if the user has better information onFlexibility or Stress Intensification Factors they should be used.

Table D-1, Flexibility and Stress Intensification Factors [25]Chart D-1, Flexibility Factor, k, and Stress Intensification

Factor, i [25]Chart D-2, Correction Factor, c [25]Fig. D-1, Branch Connection Dimensions [25]

35.9.5 Mandatory Appendix FReference Standards

Any listed standards or references in the Code are to a genericstandard without the edition or date. The most recently approvededition is noted in this appendix. This is a very difficult task andthis appendix is frequently out of date in the ASME B31.1 Codeand other ASME Codes. ASME is currently working on this issueand hopes to improve how approved editions are reviewed andupdated in the future.

35.9.6 Mandatory Appendix GNomenclature Information

A useful list of the Symbols used in the code along with defini-tion and reference to paragraphs where they are used.

35.9.7 Mandatory Appendix HPreparation of Technical Inquiries

ASME procedures have specific administrative requirementsassociated with how inquires can be submitted to the Code, andwhat types of questions will and will not be answered by theSection Committee. This Appendix provides the user some infor-mation on how to submit an inquiry or request to the committeefor Code revisions. All previously issued interpretations are pub-lished on the ASME Web site at the URL noted below. These pre-vious interpretations can be useful in understanding Code rulesand reviewing previous interpretations can be much faster thansubmitting a new inquiry.

ASME issues written replies to inquiries concerning inter-pretations of technical aspects of this Code. Interpretations,Code Cases, and errata are published on the ASME Web siteunder the Committee Pages at http://cstools.asme.org as theyare issued. Interpretations and code cases are also includedwith each edition.

35.9.8 Mandatory Appendix J Quality Control Requirements for BoilerExternal Piping (BEP)

This appendix provides the basic requirements for a qualityprogram which is required for fabrication and installation ofBoiler External Piping.

35.9.9 Nonmandatory Appendix IIRules for the Design of Safety ValveInstallations

These rules were developed some time ago and may not beconservative for supercritical steam. The user should verify dis-charge loads with the relief valve manufacture if there is anydoubt on what loads to use.

Also refer to ASME B&PV Code Section I for additional guid-ance on supercritical systems.

PROPRIETARY A

SME


35.9.10 Nonmandatory Appendix IIIRules for Nonmetallic Piping and Piping LinedWith Nonmetals

Para. 105.3 of ASME B31.1 identifies limited service condi-tions where nonmetallic pipe is permitted in power plant piping.Where it is permitted, this appendix provides guidance.

The user is cautioned the Non-metallic industry is not as stan-dardized as steel and other metal products, as a result the com-pliance with supplier requirements and recommendations isimportant with most nonmetallic piping materials and components.

Guidance for nonmetallic piping and piping lined with non-metals are in this appendix which is organized much like the baseCode. The behavior of nonmetallic piping is different than metal-lic piping, and the design criteria are significantly less well devel-oped. Supplemental rules are also provided for nonmetallic liningof metallic piping.

References 18 and 19 provide background on this appendixwhich was originally written as Chapter VII for ASME B31.3[26]. ASME BPV Code Section X, RTP-1-2011, [24], and WRC415 [20] provide information on Reinforced-Thermosetting Resindesign and component standards.

35.9.10.1 Allowable Stress Various nonmetals have different,established methods of determining allowable stresses. Somelimited allowable stress values are provided in Table III.4.2.1[25] for thermoplastic and Table III.4.2.1 [25] for reinforcedthermosetting resin pipe. For the most part, allowable stresses orpressure ratings must be determined from tests performed by themanufacturer.

35.9.10.2 Pressure Design The philosophy of the base Codewith respect to metallic piping applies to nonmetallic piping. Theprimary differences are that the table of listed components fornonmetallic piping is Table III-4.1.1 [25] rather than Table 126.1[25], and the pressure design equations are slightly different thanthe base Code.

Listed components with established ratings are accepted atthose ratings. Listed components without established ratings, butwith allowable stresses listed, can be rated using the pressuredesign rules of III-2.2.2; however, these are very limited. In thecases of listed components without allowable stresses or unlistedcomponents, components must be rated per para. III-2.2.9. Manytimes this may be done by the manufacturer, however the designeris still responsible for verifying the manufactures qualificationmeet the requirements of the Code.

35.9.10.3 Flexibility and Support Rules regarding flexibilityand support for nonmetallic piping are provided in III-2.5. Theappendix does not provide detailed rules for evaluation of non-metallic piping systems for thermal expansion. However, itrequires a formal flexibility analysis when the listed exemptionsfrom formal flexibility analysis are not met.

One of the significant differences from metallic systems is thatfully restrained designs are commonly used. That is, systemswhere the thermal expansion is offset by elastic compression/extension of the piping between axial restraints. This is possiblebecause of the relatively low elastic modulus of plastic piping.The resulting loads are generally reasonable for the design ofstructural anchors. Note, however, in performing a computer flexi-bility analysis of such systems, the axial load component of ther-mal expansion stress must be included.

A lot of other warnings or requirements are included in thissection and should be reviewed before any nonmetallic piping isdesigned or analyzed.

35.9.10.4 Materials Thermoplastic materials may only be usedfor flammable fluid service when they are underground.

Recommended maximum and minimum temperatures are gen-erally provided. If a material is to be used at a temperature belowthe minimum temperature listed in Table III-4.2.1 [25] and TableIII-4.2.1 [25], the designer must have some test results at or belowthe lowest use temperature that ensure that the materials andbonds will have adequate toughness and are suitable at the designminimum temperature.

35.9.10.5 Bonding of Plastics One of the key elements to suc-cessful construction of a plastic piping system is the joints.Appendix III requires a formal process of developing, document-ing, and qualifying bonding procedures and personnel performingthe bonding.

The first step is to have a documented bonding procedure speci-fication (BPS). The specification must document the proceduresfor making the joint, as set forth in para. III-5.1. This proceduremust be qualified by a bonding procedure qualification test.

Once it is so qualified, it may be used by personnel to bondnonmetallic piping systems. Those bonders, however, must alsobe qualified to perform the work. Bonders are qualified in a per-formance qualification test. The qualification test for the bondingprocedure and the bonder are the same. Also similar to welding, ifthe bonder has not used the procedure for a period of time, theymust be requalified. While this may seem like a lot for a proce-dure which seems to require a lot less skill than welding, many ofthe problems associated with nonmetallic piping are the result ofnot understanding or following the correct bonding procedures.

35.9.10.6 Examination and Testing The nondestructive exam-ination techniques for nonmetallic piping are not as well devel-oped as they are for metallic piping. As a result, the techniquesthat are used are visual and in-process examination or specific tothe manufacture of the components.

35.9.10.7 Requirements for Leak Testing NonmetallicPiping The leak test rules in the base Code apply to NonmetallicPiping. Excessive hydrotest pressures in fiberglass systems havecaused subsequent failures in service. The overload condition candamage the material without evidence of a leak during the testitself.

An addition warning not included in the code is the nature ofnonmetallic piping is it is much softer than metallic piping.During pressurizing and particularly during pressure test, it willelongate (if not restrained) significantly more than metallic pip-ing. This can cause more energy to be released during a failure ofa joint during hydrotesting of long runs of piping. Additionalsafety considerations should be taken to protect personnel whilethe piping is pressurized to 1.5 times the design pressure.

35.9.11 Nonmandatory Appendix IV Corrosion Control for ASME B31.1 Power Piping Systems

Appendix IV provides a lot of useful information for any pip-ing systems which will be installed underground as well as con-trol of above ground piping from internal corrosion. As always,

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35-22 • Chapter 35

the owner should supplement these requirements based on theirspecific chemistry and experience.

35.9.12 Nonmandatory Appendix VRecommended Practice for Operation,Maintenance, and Modification of PowerPiping Systems

This non-mandatory appendix was put in the Code in the 80’sand some of the recommendations in it have recently been addedto the base code as Chapter VII which was previously discussed.Also provided are a lot of good recommendations for monitoringof piping systems and their supports to ensure safe operation ofcritical piping systems.

Guidance on systems which operate in the creep range andemphasis on temperature excursions on the design life of pipingsystems in this range are provided in V-12. References 9 and 10provide additional information for piping in the creep range.

35.9.13 Nonmandatory Appendix VI Approval of New Materials

This appendix is provided to guide the user on the informationand procedures to get a new material incorporated into the code. Itprovides both the required information on the material propertieswhich must be developed as well as procedures required withinASME and ASTM.

35.9.14 Nonmandatory Appendix VII Procedures for the Design of RestrainedUnderground Piping

This appendix provides useful information for the design andanalysis of piping systems installed underground. The basis ofthis guidance comes from reference 21.

35.10 REFERENCES

1. Boardman, H. C., “Formulas for the Design of Cylindrical andSpherical Shells to Withstand Uniform Internal Pressure,” The WaterTower, vol. 30, 1943.

2. Bergman, E. O., “The New-Type Code Chart for the Design ofVessels Under External Pressure,” Pressure Vessel and PipingDesign, Collected Papers 1927–1959, The American Society ofMechanical Engineers, 1960, pp. 647–654.

3. Holt, M., “A Procedure for Determining the Allowable Out-of-Roundness for Vessels Under External Pressure,” Pressure Vessel andPiping Design, Collected Papers 1927–1959, The American Societyof Mechanical Engineers, 1960, pp. 655–660.

4. Saunders, H. E., and Windenburg, D., “Strength of Thin CylindricalShells Under External Pressure,” Pressure Vessel and Piping Design,Collected Papers 1927–1959, The American Society of MechanicalEngineers, 1960, pp. 600–611.

5. Windenburg, D., and Trilling, C., “Collapse by Instability of ThinCylindrical Shells Under External Pressure,” Pressure Vessel andPiping Design, Collected Papers 1927–1959, The American Societyof Mechanical Engineers, 1960, pp. 612–624.

6. Windenburg, D., “Vessels Under External Pressure: Theoretical andEmpirical Equations Represented in Rules for the Construction ofUnfired Pressure Vessels Subjected to External Pressure,” PressureVessel and Piping Design, Collected Papers 1927–1959, TheAmerican Society of Mechanical Engineers, 1960, pp. 625–632.

7. Biersteker, M., Dietemann, C., Sareshwala, S., and Haupt, R. W.,“Qualification of Nonstandard Piping Product Form for ASME Codefor Pressure Piping, B31 Applications,” Codes and Standards andApplications for Design and Analysis of Pressure Vessels and PipingComponents, PVP vol. 210–1, The American Society of MechanicalEngineers, 1991.

8. Markl, A., “Fatigue Tests of Piping Components,” Pressure Vesseland Piping Design, Collected Papers, 1927–1959, The AmericanSociety of Mechanical Engineers, pp. 402–418, 1960.

9. Robinson, E. “Steam-Piping Design to Minimize Creep Concen-trations,” Pressure Vessel and Piping Design, Collected Papers,1927–1959, pp. 451–466, 1960.

10. Becht IV, C., “Elastic Follow-up Evaluation of a Piping System witha Hot Wall Slide Valve,” Design and Analysis of Piping, PressureVessels, and Components-1988, PVP-Vol. 139, The AmericanSociety of Mechanical Engineers, 1988.

11. Bednar, H., Pressure Vessel Design Handbook, Van NostrandReinhold Co., New York, 1986.

12. Becht, C., Chen, Y. and Benteftifa, C., “Effect of Pipe Insertion onSlip-On Flange Performance,” Design and Analysis of PressureVessels, Piping, and Components-1992, PVP-Vol. 235, The AmericanSociety of Mechanical Engineers, 1992.

13. Sims, J., “Development of Design Criteria for a High Pressure PipingCode,” High Pressure Technology—Design, Analysis, and Safety ofHigh Pressure Equipment, PVP-Vol 110, Ed. D. P. Kendall, TheAmerican Society of Mechanical Engineers, 1986.

14. Piping Engineering, Sixth Edition, 1986, Tube Turns, Inc.

15. Piping Design & Engineering, Seventh Edition, 1995 GrinnellCorporation.

16. STP-PT-028, Impact Testing Exemption Curves for Low TemperatureOperation of Pressure Piping.

17. Harvey, John F., Theory and design of modern pressure vessels, VanNostrand Reinhold Co., New York. 1974.

18. Short II, W. E., “Overview of Chapter VII, Nonmetallic Piping andPiping Lined with Nonmetals in the ASME B31.3 Chemical Plant &Petroleum Refinery Piping Code,” Codes and Standards andApplications for Design and Analysis of Pressure Vessel and PipingComponents-1989, ASME PVP-Vol. 161, American Society ofMechanical Engineers, 1989.

19. Short II, W. E., “Coverage of Non-Metals in the ASME B31.3Chemical Plant and Petroleum Refinery Piping Code,” Journal ofProcess Mechanical Engineers, IMechE Vol. 206, pp. 67–72,Institute of Mechanical Engineers, May 1992.

20. WRC 415, Literature Survey and Interpretive Study on Thermoplasticand Reinforced-Thermosetting-Resin Piping and Component Standards,W. E. Short II, G. F. Leon, G. E. O. Widera, and C. G. Zui, TheWelding Research Council, September, 1996.

21. Goodling, E.C. “Buried Piping-An Analysis Procedure Update,”ASME Publication PVP-Vol. 77, pp. 225–237, ASME PressureVessels and Piping Conference, Portland, June 1983.

22. Nayyar, Mohinder L., Piping Handbook, Mcgraw-Hill SeventhEdition.

23. ASME PCC-1, Guidelines for Pressure Boundary Bolted FlangeJoint Assembly, The American Society of Mechanical Engineers,2010.

24. RTP-1, 2011, Reinforced Thermoset Plastic Corrosion-ResistantEquipment.

25. ASME B31.1, Power Piping Code, 2010 Edition.

26. ASME B31.3, Process Piping Code, 2010 Edition.

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27. ASME B31.4, Liquid Transportation Systems for Hydrocarbons,Liquid Petroleum Gas, Anhydrous Ammonia, and Alcohols; TheAmerican Society of Mechanical Engineers.

28. ASME B31.5, Refrigeration Piping; The American Society ofMechanical Engineers.

29. ASME B31.8, Gas Transmission and Distribution Piping Systems;The American Society of Mechanical Engineers.

30. ASME B31.9, Building Services Piping; The American Society ofMechanical Engineers.

31. ASME B31J, Standard Method to Develop Stress Intensification andFlexibility Factors for Piping Components; The American Society ofMechanical Engineers; under development.

API 526, Flanged Steel Pressure Relief Valves; The American PetroleumInstitute.

API 570, Piping Inspection Code: Inspection Repair, Alteration, andRerating of In-Service Piping Systems; The American PetroleumInstitute.

API 594, Wafer and Wafer-Lug Check Valves; The American PetroleumInstitute.

API 599, Metal Plug Valves—Flanged and Welding Ends; The AmericanPetroleum Institute.

API 600, Steel Gate Valves—Flanged, Threaded and Butt-Welding EndsBolted and Pressure Seal Bonnets; The American PetroleumInstitute.

API 602, Compact Steel Gate Valves — Flanged, Threaded, Welding andExtended Body Ends, The American Petroleum Institute.

API 603, Class 150, Cast, Corrosion-Resistant, Flanged-End GateValves, The American Petroleum Institute.

API 608, Metal Ball Valves — Flanged, Threaded, and Butt-WeldingEnds, The American Petroleum Institute.

API 609, Butterfly Valves: Double Flanged, Lug- and Water-Type, TheAmerican Petroleum Institute.

ASME Boiler and Pressure Vessel Code Section I, Power Boilers, TheAmerican Society of Mechanical Engineers.

ASME Boiler and Pressure Vessel Code Section II, Part A, Materials,Ferrous Material Specifications; The American Society of Mecha-nical Engineers.

ASME Boiler and Pressure Vessel Code Section II, Part B, Materials,Nonferrous Material Specifications; The American Society ofMechanical Engineers.

ASME Boiler and Pressure Vessel Code Section III, Rules forConstruction of Nuclear Power Plant Components; The AmericanSociety of Mechanical Engineers.

ASME Boiler and Pressure Vessel Code Section VIII, Division 1,Pressure Vessels; The American Society of Mechanical Engineers.

ASME Boiler and Pressure Vessel Code Section VIII, Division 2,Pressure Vessels, Alternative Rules; The American Society ofMechanical Engineers.

ASME Boiler and Pressure Vessel Code Section IX, Welding andBrazing Qualifications; The American Society of MechanicalEngineers.

ASME B16.1, Cast Iron Pipe Flanges and Flanged Fittings; AmericanNational Standards Institute.

ASME B1.20.1, Pipe Threads, General Purpose (Inch); The AmericanSociety of Mechanical Engineers.

ASME B16.3, Malleable Iron Threaded Fittings; The American Societyof Mechanical Engineers.

ASME B16.4, Gray Iron Threaded Fittings, The American Society ofMechanical Engineers.

ASME B16.5, Pipe Flanges and Flanged Fittings, The American Societyof Mechanical Engineers.

ASME B16.9, Factory-Made Wrought-Steel Butt welding Fittings, TheAmerican Society of Mechanical Engineers.

ASME B16.10, Face-to-Face and End-to-End Dimensions of Valves, TheAmerican Society of Mechanical Engineers.

ASME B16.11, Forged Steel Fittings, Socket-Welding and Threaded, TheAmerican Society of Mechanical Engineers.

ASME B16.14, Ferrous Pipe Plugs, Bushings, and Locknuts with PipeThreads, The American Society of Mechanical Engineers.

ASME B16.15, Cast Bronze Threaded Fittings, Classes 125 and 250, TheAmerican Society of Mechanical Engineers.

ASME B16.18, Cast Copper-Alloy Solder-Joint Pressure Fittings, TheAmerican Society of Mechanical Engineers.

ASME B16.22, Wrought Copper and Copper-Alloy Solder-Joint PressureFittings, The American Society of Mechanical Engineers.

ASME B16.24, Bronze Pipe Flanges and Flanged Fittings, Classes 150,300, 400, 600, 900, 1500, and 2500 and Flanged Fittings, Classes150 and 300; The American Society of Mechanical Engineers.

ASME B16.26, Cast Copper Alloy Fittings for Flared Copper Tubes, TheAmerican Society of Mechanical Engineers.

ASME B16.28, Wrought-Steel Buttwelding Short Radius Elbows andReturns, The American Society of Mechanical Engineers.

ASME B16.34, Valves—Flanged, Threaded, and Welding End, TheAmerican Society of Mechanical Engineers.

ASME B16.36, Orifice Flanges, Classes 300, 600, 600, 900, 1500, and2500; The American Society of Mechanical Engineers.

ASME B16.39, Malleable Iron Threaded Pipe Unions, Classes 150, 250,and 300; The American Society of Mechanical Engineers.

ASME B16.42, Ductile Iron Pipe Flanges and Flanged Fittings, Classes150 and 300; The American Society of Mechanical Engineers.

ASME B16.47, Large Diameter Steel Flanges, NPS 26 Through NPS 60;The American Society of Mechanical Engineers.

ASME B16.48, Steel Line Blanks; The American Society of MechanicalEngineers.

AWWA C110, Ductile-Iron and Gray-Iron Fittings, 3 Inch Through 48Inch (75 mm Through 1200 mm), for Water and Other Liquids;American Water Works Association.

AWWA C115, Flanged Ductile-Iron with Ductile-Iron or Gray-IronThreaded Flanges, American Water Works Association.

AWWA C207, Steel Pipe Flanges for Water Works Service, Sizes 4 InchThrough 144 Inch (100 mm Through 3,600 mm); American WaterWorks Association.

AWWA C208, Dimensions for Fabricated Steel Water Pipe Fittings,American Water Works Association.

AWWA C 500, Metal-Seated Gate Valves for Water Supply Service,American Water Works Associations.

AWWA C 504, Rubber-Seated Butterfly Valves, American Water WorksAssociation.

MSS SP-42, Class 150 Corrosion-Resistant Gate, Globe, Angle, andCheck Valves With Flanged and Butt Weld Ends; ManufacturersStandardization Society of the Valve and Fittings Industry, Inc.

MSS SP-43, Wrought Stainless Steel Butt Welding Fittings, ManufacturersStandardization Society of the Valve and Fittings Industry, Inc.

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35-24 • Chapter 35

MSS SP-44, Steel Pipe Line Flanges, Manufacturers StandardizationSociety of the Valve and Fittings Industry, Inc.

MSS SP-51, Class 150 LW Corrosion-Resistant Cast Flanges andFlanged Fittings, Manufacturers Standardization Society of the Valveand Fittings Industry, Inc.

MSS SP-65, High-Pressure Chemical Industry Flanges and ThreadedStubs for Use with Lens Gaskets, Manufacturers StandardizationSociety of the Valve and Fittings Industry, Inc.

MSS SP-70, Cast Iron Gate Valves, Flanged and Threaded Ends,Manufacturers Standardization Society of the Valve and FittingsIndustry, Inc.

MSS SP-71, Cast Iron Swing Check Valves, Flanged and Threaded Ends,Manufacturers Standardization Society of the Valve and FittingsIndustry, Inc.

MSS SP-72, Ball Valves With Flanged or Buttwelding Ends for GeneralService; Manufacturers Standardization Society of the Valve andFittings Industry, Inc.

MSS SP-73, Brazing Joints for Copper and Copper Alloy PressureFittings.

MSS SP-75, Specifications for High Test Wrought Buttwelding Fittings,Manufacturers Standardization Society of the Valve and FittingsIndustry, Inc.

MSS SP-79, Socket-Welding Reducer Inserts; Manufacturers Standar-dization Society of the Valve and Fittings Industry, Inc.

MSS SP-80, Bronze Gate, Globe, Angle, and Check Valves, Manu-facturers Standardization Society of the Valve and Fittings Industry,Inc.

MSS SP-81, Stainless Steel, Bonnetless, Flanged, Knife Gate Valves,Manufacturers Standardization Society of the Valve and FittingsIndustry, Inc.

MSS SP-83, Class 3000 Steel Pipe Unions, Socket-Welding andThreaded; Manufacturers Standardization Society of the Valve andFittings Industry, Inc.

MSS SP-85, Cast Iron Globe and Angle Valves, Flanged and ThreadedEnds, Manufacturers Standardization Society of the Valve andFittings Industry, Inc.

MSS SP-88, Diaphragm-Type Valves, Manufacturers StandardizationSociety of the Valve and Fittings Industry, Inc.

MSS SP-95, Swage (d) Nipples and Bull Plugs, Manufacturers Standar-dization Society of the Valve and Fittings Industry, Inc.

MSS SP-97, Integrally Reinforced Forged Branch Outlet Fittings —Socket Welding, Threaded, and Buttwelding Ends; ManufacturersStandardization Society of the Valve and Fittings Industry, Inc.

MSS SP-105, Instrument Valves for Code Applications, ManufacturersStandardization Society of the Valve and Fittings Industry, Inc.

MSS SP-58, Pipe Hangers and Supports—Materials, Design, andManufacture; Manufacturers Standardization Society of the Valveand Fittings Industry, Inc.

SAE J513, Refrigeration Tube Fittings — General Specifications; Societyof Automotive Engineers.

SAE J514, Hydraulic Tube Fittings; Society of Automotive Engineers.

SAE J518, Hydraulic Flange Tube, Pipe, and Hose Connections, Four-Bolt Split Flanged Type; Society of Automotive Engineers.

WRC 107, Wichman, K., Hopper, A., and Mershon, J. (1979). “LocalStresses in Spherical and Cylindrical Shells due to ExternalLoadings,” Welding Research Council, Bulletin 107, New York.

WRC 297, Mershon, J., Mokhtarian, K., Ranjan, G., and Rodabaugh, E.(1984). “Local Stresses in Cylindrical Shells due to External Loadingson Nozzles—Supplement to WRC Bulletin No. 107,” WeldingResearch Council, Bulletin 297, New York.

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36.1 COVERAGE

The ASME B31.3 Process Piping Code is one of a series ofpiping codes which cover piping for various industries. The previ-ous chapter covered the first in the series which is ASME B31.1the power piping code. Likewise, this and subsequent chapters orsub chapters will cover the rest of the B31 series of piping codes.This series of piping codes started with the Pressure Piping Codewhich was first published in 1935. More information on the his-tory is printed in the forward of ASME B31.3 as well as others inthe series.

This chapter covers some of the other books in the B31 seriesas listed below:

In PART A: B31.3 – Process Piping;In PART B: B31.5–2010 Refrigeration Piping and Heat Trans -

fer Components;

In PART C: B31.9-2011 Building Services Piping;In PART D: B31E–2008 Standard for the Seismic Design and

Retrofit of Above-Ground Piping Systems;In PART E: B31J–2008 Standard Test Methods for Determin -

ing Stress Intensification Factors (i-Factors) for Metallic PipingComponents; and

In PART F: B31T–2010 Standard Toughness Requirements forPiping.

At the end of this chapter 36 references pertaining to all of theabove Parts A through F are provided. Whereas some of these ref-erences are directly applicable to the discussions contained in thischapter several others are noted for additional information.

PART A: ASME CODE B31.3 – PROCESSPIPING

36A1 INTRODUCTION

This part of the chapter is based on the 2010 Edition of theASME B31.3 Process Piping Code and will be referred to as theCode hereafter.

The introduction of the any of the book sections as they arereferred to within ASME gives a brief description of the scope of

CHAPTER

36

ASME PIPING CODES: B31.3 PROCESS, B31.5 REFRIGERATION,

B31.9 BUILDING SERVICES

AND

ASME STANDARDS FOR PIPING: B31E SEISMIC DESIGN,

B31J STRESS I-FACTORS, B31T TOUGHNESS REQUIREMENTS

Jimmy E. Meyer1

1Charles Becht IV was the author of “Chapter 17” titled “B31.3 PROCESSPIPING” for the original, second and third editions. Chapter 17 of the thirdedition has been revised in its entirety and renumbered as Chapter 36 in thecurrent fourth edition. As noted in the title this chapter 36 for the fourth edi-tion is authored by Jimmy E. Meyer who enlarged the scope of the chapter toinclude additional ASME B31 Codes and Standards. − (Editor)

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the book sections and identifies the responsibility for the owner toselect the applicable Code section for the design of piping relatedto their facility. This is one of several important responsibilitiesassigned to the “owner” who is defined in the first section ofB31.3 Paragraph 300(b)(1). Another useful piece of informationto understand is the numbering of paragraphs, figures and tablesin the piping codes. All of the numbered book sections startedfrom a single pressure piping code as noted above, as the specificbook sections were split apart for specific types of services orindustries, there was an attempt to maintain the paragraph num-bering with the exception of first number in the series. For exam-ple all of the paragraphs in B31.1 are in the 100 series likewise allof the paragraphs in B31.3 are in the 300 series. This is not anabsolute, but it will give you a good starting point if for the readerto use more than one of the ASME B31 series in the reader’scareer.

The use of the term piping is meant to apply to more than Pipe.Pipe, Piping, Piping Components, Piping Elements, PipingInstallation, and Piping Systems all have specific definitions pro-vided in Para. 300.2 and should be reviewed to understand therequirements in the B31.3 Process Piping code as well as the restof this chapter. Another important point which is made in theintroduction of B31.3 as well as other book section is “the Code isnot a design handbook”. Since this is not emphasized sufficiently,this will be repeated a few more times throughout this chapter.Since this is a companion guide the code requirements will not beduplicated, instead frequent references to the applicable para-graphs and some insights to the requirements or a simpler way tolook at them to help the user understand them will be made. Manyof the explanations may be oversimplifications and should not betaken as the complete code requirements. The code is updated fre-quently and is considerably more thorough than this guide.

After the Introduction, the Code is organized much the same asa design and construction project for the first Chapters:

Chapter I, Scope and DefinitionsChapter II, DesignChapter III, MaterialsChapter IV, Standards for Piping ComponentsChapter V, Fabrication, Assembly and ErectionChapter VI, Inspection, Examination, and Testing

The last four chapters of the Code provide additional rules orexemptions for specific materials or service conditions. Thesechapters follow the same format as the previous chapters andparagraph numbering with the exception of a letter designationbeing added. If these chapters do not apply to a project or work,there is no reason to deal with them:

Chapter VII, Nonmetallic Piping and Metallic Piping Lined withNonmetals.Chapter VIII, Piping for Category M Fluid Service (Note, this isfor highly hazardous fluid services which the owner designatesrequires additional considerations and safeguarding.)Chapter IX, High Pressure PipingChapter X, High Purity Piping (This is a new chapter which wasjust added in the 2010 edition and addresses some different jointdesigns and fabrication techniques for a number of industriesrequiring extremely clean conditions.)

Treatment in this chapter follows the same order as shownabove. A list of references is provided at the end of the chapter forthe reader to explore the topics in more detail.

36A2 SCOPE AND DEFINITIONS

Para. 300.1.1(b) below specifically lists a number of fluidswhich the Code applies to:

(b) This Code applies to piping for all fluids, including(1) raw, intermediate, and finished chemicals(2) petroleum products(3) gas, steam, air, and water(4) fluidized solids(5) refrigerants(6) cryogenic fluids

The above list is not complete and B31.3 being the mostgeneric of the Pressure Piping Codes in the B31 series is also fre-quently applied to the following industries or fluid services:

Food and PharmaceuticalNuclear Fuel and Waste ProcessingSemiconductor ManufacturingBioprocessing Industry

Most of the facilities listed above are the industries whichresulted in the need to add Chapter X to the code to address thehigh purity requirements of these industries.

36A3 DESIGN

36A3.1 Chapter II, Part 1, Design Conditions

36A3.1.1 (Para. 301) Qualifications of the Designer Asnoted during the introduction, the Code is not a design handbook,so Para. 301.1 identifies experience/educational re quire ments fora Piping Designer. This is very difficult to do be cause experienceand complexity of piping systems vary so widely so the option ofusing less experienced design personnel is left to the owner.Likewise, an experienced designer must be aware of piping sys-tems or conditions where they might not have the required expe-rience to safely design a piping system and seek more qualifiedhelp.

The rest of paragraph 301 provides a short explanation of con-ditions or considerations for the design of piping systems. It is afairly comprehensive list, but the owner or designer should alwaysbe on the lookout for unique conditions which might not beaddressed.

36A3.2 (Para. 302) Design CriteriaThis section defines the basis of the allowable stresses, quality

factors, etc. to be used for the design of piping systems. It also in -cludes some references to listed and unlisted components and anallowance for short term variations. The user is cautioned to besure they have enough understanding of future operation of thesystem before they apply these allowances. Generally process pip-ing facilities are designed for a 20-40 year life or more. Unlessthe variations are self-limiting (for example a relief valve dis-charging), it is difficult for a designer to assure himself of theduration of variations to design conditions.

36-2 • Chapter 36

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36A3.2.1 (Para. 302.3.5) Sustained Loads and DisplacementStrains This might be the most important paragraph to understandthe analysis and design requirements in the Code. The simplifiedanalysis requirements in the Code are separated into SustainedLoads which will act until a system fails if it exceeds the limits ofthe material and Displacement Strains (self limiting) or loads whichhave a defined displacement and will not continue past this limit.

Examples of Sustained loads and Stresses:Internal Pressure (hoop stress) Sh

Internal Pressure (longitudinal stress) (SL Para. 302.3.5(c))Bending Stress from weight (longitudinal, shear or torsion)

(SL Para. 302.3.5(c))Bending Stress from occasional loads such as wind, snow andSeismic (SL *1.33 Para. 302.3.6)

As a footnote it can be mentioned that seismic loads are usu-ally treated as sustained loads by various Codes, however a lot ofresearch indicates seismic failures are more closely associatedwith fatigue or self limiting loads. References 25 to 31 pertinentto Seismic Design in general are listed at the end of this chapter.

Examples of Displacement Strains (Self Limiting)Stresses due to thermal Expansion Sa � f(1.25Sc � .25Sh). Anchor movements caused by settlement, equipment movement,etc. Sa � f(1.25Sc � .25Sh).

The limits for sustained loads are roughly 2/3 of the yieldstrength of a material, or 1/3 of the tensile strength of a material.The limit for displacement strains (self limiting stresses) can be ashigh as twice the yield strength of the material. Equation (1a) is

the first equation in the code and defines the allowable displace-ment stress range Sa � f(1.25Sc � .25Sh). Sc and Sh are the basicallowable stress for the materials for at minimum and maximumexpected temperatures. “f” is a fatigue factor based on the numberof cycles expected during the service life of the system. Thefatigue factor “f” is 1 for less than 7,000 cycles unless the require-ments for low cycle fatigue are met. See figure 36A3.2.1 fordetermining an “f” factor for cycles other than 7,000.

The analysis requirements for both Sustained and Self Limitingloads will be discussed later in this chapter, but the two load casesare treated separately by the Code with two minor exceptions.

The first is equation (1b): Sa � f[1.25(Sc � Sh) �SL]. This equation still does not do anything to combine the two

load cases. If studied carefully, it roughly increases the stressrange from 1.5 times the basic allowable stress to 2.5 times thebasic allowable stress minus the longitudinal stress from the com-bination of sustained loads. So again, the code does not combinesustained and self limiting load cases, it only allows an increase inthe displacement stress range allowable for any unused part of thesustained stress allowable. The user is urged to review the require-ments of this paragraph carefully to fully understand the differ-ence between the two types of loading and the code treatment ofthem. This will also be discussed during the analysis requirements(Para. 319) later in this chapter.

The second exception is not even in the base code. It is foundin Appendix P which provides Alternative Rules for EvaluatingStress Range. This appendix does not eliminate the requirementto meet sustained load requirements in the base Code, it just pro-vides an alternate method to evaluate the stress range require-ments. This is a relatively new appendix in the code, and there are


FIG. 36A3.2.1 STRESS RANGE FACTOR, f (Source: Fig. 302.3.5 of ASME B31.3, 2010)

PROPRIETARY A

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already some members of the Process Piping Code SectionCommittee who feel is should be deleted from the code.

References 8, 9, 10, 14 and 21 provide more in depth informa-tion on the stress range concept and associated stress intensifica-tion factors discussed later.

36A3.3 Part 2 Pressure Design of Piping Components

36A3.3.1 (Para. 303) General The easiest way to meet thepressure design for a component is to use components which aremanufactured to a standard listed in Table 326.1. These listed stan-dards also provide pressure temperature ratings for the components,either in the form of a table with coincident pressures/temperatures(for example B16.5, B16.47, etc.), or ratings associated with com-patible seamless pipe (for example B16.9, B16.11, etc).

Unlisted components may be used, however a lot more re -sponsibility is put on the designer to verify they are good for thepressure, temperature and other loading requirements in the code.Reference 7 provides additional guidance for Unlisted Compo -nents. The number of reference standards associated with pipingdesigns are quite significant, the following Table 36A3.3.1 givessome examples of how the piping codes are interrelated for somecommon carbon steel (CS) and stainless steel (SS) PressureRating/Dimensional Standards, Material Forming Standards andMaterial Grades.

36A3.3.2 Pressure Design

36A3.3.2.1 Straight Pipe This section defines a lot of termsassociated with the calculation of the required wall thickness forinternal pressure.

During the development of the Code approximately 30 differ-ent equations were considered for the calculation of required wallthickness. If the piping were infinitely thin, the simple equation of“t�PD/2SEW” where t� minimum calculated wall thickness, P� design pressure, D� Pipe Outside Diameter, SEW � basicallowable stress (including weld quality and weld strength reduc-tion factors) would provide accurate or conservative results. Sinceit must have some thickness, the Code settled on equation (3a)“t�PD/2(SEW�Py) because it is relatively simple and providegood results compared with more complicated formulas. Table304.1.1 provides values for the “y” factor which is .4 for most lowtemperature ductile materials. Equation (3b) is also provided forthe user if they would like to start with the ID and calculate aminimum wall thickness.

Equations (3a and 3B) are only for Diameter to wall thicknessratios of 6 or greater. For thick wall designs where this require-ment is not met, the user should consider such factors as theory offailure, effects of fatigue, and thermal stress (see references at theend of this chapter). Chapter IX was developed to provide extraguidance/requirements for these high pressure applications.

References 1, 11, 13, 14, and 17 provide more detailed expla-nations and the theory behind these equations.

36A3.3.2.2 Straight Pipe Under External Pressure For exter-nal pressure whether from a vacuum condition in the pipe, or jack-eting with steam, para. 304.1.3 of the Code refers to ASME Boilerand Pressure Vessel Code Section VIII for the design requirements.

See References 2, 3, 4, 5, 6 and 17 for addition information onExternal Pressure or Vacuum Design of piping and components.

36A3.3.2.3 Curved and Mitered Segments of Pipe Para.304.2 has similar equations to those for straight pipe, these areprovided for piping bends and miters. While these equations are alittle more complicated than straight pipe, repeating them here

36-4 • Chapter 36

TABLE 36A3.3.1 EXAMPLES OF LISTED STANDARDS FOR COMPONENTS AND MATERIAL

ComponentCarbon Steel (CS) / Stainless Steel (SS)

Dimensional Standard / Pressure Rating

Material/ Forming Spec. Material Grade

Pipe Carbon Steel ASME B36.10 ASTM A106 or A53 Grade B (most common)Pipe Stainless Steel ASME B36.19 ASTM A312 Type 304, 304L, 316, etc.Forged Fittings 2” and Under (1) Carbon Steel ASME B16.11 ASTM A105 One GradeForged Fittings 2” and Under (1) Stainless Steel ASME B16.11 ASTM A182 Type 304, 304L, 316, etc.Formed Fittings 2 ½” and larger (1) Carbon Steel ASME B16.9 ASTM A234 Grade WPB to match pipeFormed Fittings 2 ½” and larger (1) Stainless Steel ASME B16.9 or

MSS SP 43 (2)ASTM A403 Type 304, 304L, 316, etc.

Flanges (Forged) 24” and smaller Carbon Steel ASME B16.5 ASTM A105 One GradeFlanges (Forged) 24” and smaller Stainless Steel ASME B16.5 ASTM A182 Type 304, 304L, 316, etc.Flanges over 24” CS or SS ASME B16.47 (3) See CS or SS above See CS or SS aboveForged Valves 2” and Under (1) CS or SS No Std. ASTM A105 and

A182Same as Forged Fittings

Valves Flanged or Butt Welded Carbon Steel ASME B16.34 ASTM A216 Grade WCB to match pipeValves Flanged or Butt Welded Stainless Steel ASME B16.34 ASTM A351 Type 304, 304L, 316, etc.

Notes:1. The size ranges overlap, but generally 2” and under will be socket welded forged fittings and 2 ½” and over will be butt weld (wrought)

fittings. Verify with project or client specifications.2. MSS SP 43 does not have the same pressure rating, or quality control as ASME B16.9. ASME B16.9 should be specified for any

pressure or hazardous applications.3. Use caution on flanges over 24”. This standard has two sets of flanges series A and Series B. They do not fit up with each other! These

were previously MSS SP44 flanges and API 605 flanges.

PROPRIETARY A

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will not provide the user much additional value. Some of the ref-erences provided at the end of this chapter will provide more indepth explanation into the theory if required.

36A3.3.2.4 (Para. 304.4) Branch Connections Para. 304.3of the Code provides rules based on area replacement as an alter-nate to using listed branch components from Table 326.1. Thismeans when a hole is cut in the pipe wall, area removed isreplaced within a specific distance of the area which wasremoved. The theory here is the hoop stress which is the basis ofthe wall thickness calculation will remain constant if the arearemains constant. There are about four pages of figures and defi-nition of terms/areas associated with this concept. Appendix Halso provides 5 sample problems for branch connection rein-forcement. One of these figures is 304.3.4, repeated below as fig-ure 36A3.3.2.5.

What makes it look complicated are all of the allowances onthe pipe wall and the possibility the branch is not at a right angleto the pipe centerline. If not all of the existing wall is required forpressure design (i.e. the actual pipe wall thickness exceeds theminimum wall required), then this extra wall thickness may beused for area replacement.

A simpler approach would be to calculate the minimum wallthickness required for the run pipe or header. If the actual wallthickness is not at least twice the calculated minimum wall thick-ness, most likely some area reinforcement or replacement isrequired. Unless it is very close, the author recommends specify-ing 100% replacement of area. The reinforcement area is basi-cally one branch diameter from the centerline of the branch on theheader, and 2.5 times the wall thickness of either the branch or theheader. This is fairly limiting, however if the reinforcing pad ismade from the same material and thickness as the header, and thewidth is specified with the radius of the branch, it will produce apad which will replace all of the area which was removed. Theuser is also cautioned the area replacement rules apply to the pres-sure design, the branch connection will also have to be evaluatedfor other sustained loads as well as the displacement stress range.This topic will be address more in other parts of this chapter.

ASME B&PV Code, Section VIII, Div.1, Div.2 and Div. 3 allprovide alternate methods of evaluating the intersection ofcylinders for pressure and external loads. These methods varyfrom a similar simplified approach to detailed finite elementanalysis.

36A3.4 Part 3 Fluid Service Requirements forPiping Components

Part 4 Fluid Service Requirements forPiping Joints

In the definitions, the Code defined a number of different fluidservices. Category D Fluid Service Relatively low pressure/temperature,

nonhazardous, nonflammable.Normal Fluid Service Default fluid service unless one of

the others was permitted by theOwner.

Category M Fluid Service This fluid service would present asignificant risk to personnel with asingle exposure to a small quantityof a toxic fluid.

High Pressure Fluid Service Generally, this fluid service wouldapply to pressures which exceed theflange rating of ASME B16.5, Class2500 lb flanges.

36A3.4.1 Both of these parts 3 and 4 address various pipingcomponents or types of piping joints which might be limited tononhazardous fluids, size limitation, or where additional require-ment might be required. These requirements should be reviewed,but there is no good way to summarize them. The user shouldfamiliarize themselves with these requirements especially whenthey are preparing new piping specifications for a fluid service, orworking on a piping design which does not have an approved pip-ing specification.


FIG. 36A3.3.2.5 BRANCH CONNECTION NOMENCLATURE (Source: Fig. 304.3.3 of ASME B31.3, 2010)

Limits of reinforcement zone Mill tolerance

Normal thickness

Branch pipeor nozzle

Branch pipeor nozzle

Reinforcement areas

Limits of reinforcement zone

Run pipeRun pipeA2

A2

A3

Db

Tb

A3

A1

A4A4Thickness, measured or minimum per purchase specification

Reinforcement areas

Multiply this area by(2 - sin β) to getrequired area

Normal thicknes

Mill tolerance

GENERAL NOTE: This Fiugure illustrates the nomenclature of para, 304.3.3. It does not indicate complete weldinf details or a preferred methodof construction. For typical weld details, see Fig. 328.5.4D

Pipe

d2

d1

L4

Dh d2

Tr

Tb

ThTh

th

TbC

c

PROPRIETARY A

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36A3.5 Part 5 Flexibility and Support

36A3.5.1 Piping Flexibility

36A3.5.1.1 Basic Requirements Piping systems shall havesufficient flexibility to prevent thermal expansion or contraction ormovements of piping supports and terminals from causing

(a) failure of piping or supports from overstress or fatigue(b) leakage at joints(c) detrimental stresses or distortion in piping and valves or in

connected equipment (pumps and turbines, for example),resulting from excessive thrusts and moments in the piping

The basic requirements noted above are what are normally con-sidered in the piping analysis. The stress range concept is alsoexplained in more detail in this chapter, but it was mentioned ear-lier when the allowable stress range was defined. The statementmade in the introduction of the Code “the Code is not a designhand book” is probably most applicable to this chapter. The useris also warned about the various piping analysis software productsavailable to meet the analysis requirements of this section. Theseare great tools, and provide a great deal more analysis options andload combinations than were available when the Code require-ments were first written.

As was noted, the Code treats the displacement stress rangeseparately from sustained loads. Most analysis products availablenow combine sustained and displacement load cases in someway. In most cases, they also calculate a stress associated withthis load case. There is no allowable stress associated with thisload case in the base Code. The explanation in Para. 319.2. cov-ers displacement strains, displacement stresses, displacementstress ranges and cold spring provide a good starting point forunderstanding this concept. References 8, 14, 15, and 21 at theend of this chapter also will go into the basis of this conceptmore depth.

36A3.5.2 Cold Spring The B31.1 Power Piping Code (Para.119.9) provides a little more explanation on the concept and require-ments of cold spring. Cold spring was used more widely in thePower Piping because of the large diameter hot piping connected tothe turbine. It is very difficult to meet the allowable force andmoment loading on the turbine, and cold spring was one techniqueto help reduce the loads. Many client/owner specifications now pro-hibit the use of cold spring. This is because it is extremely difficultto verify the cold spring is correctly installed during the construc-tion, and even more difficult to be sure it is maintained during main-tenance throughout the life of the plant. Also see Para. 319.5.1 forformulas to be used in calculating reaction loads when cold spring isused.

36A3.5.3 Properties for Flexibility Analysis Appendix C andD are referenced as the source for thermal expansion data, modu-lus of elasticity and flexibility and stress intensification factors.This section also identifies specific temperatures to be used for theanalysis. For example the expansion value for the stress range isthe algebraic difference between the minimum and maximum tem-peratures for the thermal cycle under analysis, while the expansionvalue for reactions is the expansion value from the expectedinstalled temperature to the maximum (or minimum) temperatureunder analysis. Appendix D contains the stress intensifications fac-tors to be used with the simplified analysis methods described in

the Code. These flexibility and stress intensification factors werefirst developed in the 1950’s. Many have not been updated sincethen, so the Code permits the use of better data if it is available to the user. ASME B31J provides a consistent method to experi-mentally develop stress intensification and flexibility factors. Thisstandard is discussed later, but it is worth noting the scope of thisstandard is being expanded to provide updated factors which havebeen developed by more recent research and will be available foruse with all of the B31 Code Sections. Also, see references 8, and14, at the end of this chapter for more information on the develop-ment of these stress intensification and flexibility factors and thetheories behind them.

36A3.5.4 Flexibility Analysis Requirements These areinteresting sections, and the user should be aware they werewritten and have been in the Code since before there was easyaccess to Piping Analysis Software. The analysis softwareavailable in the early 1970’s (and before) required a mainframe computer and piping input decks with three computerpunch cards per piping element. A piping analysis modelwhich can be developed in much less than an hour today, couldhave taken a week to input, verify and run back then. As aresult a number of approximation methods were (and still are)available. Some of these methods include Guided CantileverCharts, Tube Turn, Grinnell, and the formula provided inASME B31.3, equation (16). ASCE Manual on Steel construc-tion contains beam formulas which form the basis of most for-mal analysis software, these beam formulas can also be used toapproximate results from formal analysis. There are a lot ofwarnings and precautions for any of these methods, howevermany of the same references and warnings also apply to formalanalysis. It now takes more time to document the acceptabilityof an approximation method than to develop a formal model,however without a good understanding of the approximationmethods, the user may not have the knowledge to recognizewhen there is an error in the formal analysis. References 14,15, and 19 provide a number of simplified methods for thispurpose.

The user is strongly encouraged to have a basic expectation ofthe results of any formal computer analysis whether from pipinganalysis software, or finite element analysis. These are sometimesreferred to as “sanity checks”, rules of thumb”, “simplified ap -proxi mation methods”, etc. but regardless of what they are called,it is important to understand when the results of the computeranalysis are conservative, or when they give you the answer youwant to hear. Note the term conservative versus the term correct.It is very unlikely the analyst could ever calculate an accuratestress on a piping element after it has experienced a few thermalcycles and the tolerances associated with fabrication and con-struction. The goal is to envelop everything the piping systemcould possibly experience and make sure it is safe for those conditions.

36A.3.5.5 (Para. 319.4.3) This is a very short paragraph, how-ever it is extremely important to getting good conservative resultfrom a formal or approximation analysis. These are sometimesreferred to as boundary conditions, and many problems encoun-tered in the field are the result of inaccurate modeling of these con-ditions. One of the most important conditions is the stiffness of thesupports or restraints. Unless provided, most commercial analysissoftware will assume supports, restraints and anchors (usuallyequipment nozzles) are very rigid. This is a good assumption for

36-6 • Chapter 36

PROPRIETARY A

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maximizing the stresses developed in a piping system, but mayresult in a load being shifted to the wrong location because of therelative stiffness of the supports.

36A3.5.6 Flexibility Stresses The equations for calculatingand combining bending and torsion stresses are provide in this sec-tion. It is important to understand how the Code requires loads tobe combined, however most commercially available software willcorrectly meet these requirements if appropriate Code and de-fault requirements are set and verified prior to the analysis being performed.

36A3.5.7 Required Weld Quality Assurance It is good prac-tice not to push the design of a piping system right up to code limits because of problems which could be encountered during con-struction for the severe cyclic conditions. If the limits are pushedto within 80% of the allowable stress range and the number ofassociated thermal cycles is over 7000, the designer is responsibleto specify additional weld inspection

Para. 319.6 and 319.7 provide some additional guidance on cal-culating movements, separating analysis into smaller simpler sub-systems (highly recommended by the author) and means ofincreasing flexibility are covered in these sections and are coveredin these sections.

Before moving to the next section, the user should note significantattention has been spent on piping flexibility analysis. The next sec-tion moves on to support of the piping systems. Para. 302.3.5 identi-fied requirements for sustained loads like pressure and weight. Mostof the requirements which apply to formal analysis for piping flexi-bility can also be applied to formal analysis of piping for these sus-tained loads. As will be noted in the next section, there are a numberof approximation methods which were used before the availabilityof analysis software. One useful rule of thumb the user might finduseful is if the piping system is designed to the maximum possiblepressure per equation (3a), the longitudinal stress from pressure willbe approximately 50% of the allowable. The other 50% of the basicallowable longitudinal stress should be available for stresses devel-oped from the weight of the piping system.

36A3.6 Piping SupportPipe supports are obviously an important part of the piping

design. This chapter is relatively straight forward and providesinformation to be considered during the design and support ofpiping systems. In addition to the requirements in this section ofthe code, MSS-SP58, 2002 edition, and the support manufacturesprovide additional information on the design of pipe supports. Apoint worth highlighting the term support also applies to re -straints. The term restraint is more likely to apply to restraints inthe axial or lateral direction relative to the pipe. These restraintsare important for seismic or wind loading as well as restraintsrequired to control the thermal expansion of the piping. Whererestraints are used to control the thermal expansion of longstraight runs of thermal expansion, the user must make sure loadsfrom friction are added to the loads from the flexibility analysis.While friction can be included in the flexibility analysis, this canbe complicated and it is common practice to calculate frictionalloads separately and add them to the support loads. The mostimportant consideration with friction is it can never help the user.This is probably the best reason not to include it in the pipinganalysis, because the analysis is performed without being sure itis helping one of the load cases.

36A3.6.1 Anchors and Guides “(c) Piping layout, anchors,restraints, guides, and supports for all types of expansion jointsshall be designed in accordance with para. X301.2 of AppendixX.”

This is a very small little paragraph, but when dealing withexpansion joints it is extremely important. The user must under-stand the pressure thrusts developed by expansion joints andrestraint systems associated with them. Failure to understand thisresulted in one of the worst industrial accidents in the 1970’swhich killed about 29 workers. Most expansion joint manufac-tures provide very good design information on calculating andcontrolling this pressure thrust as well is information on theallowable movements associated with their products. This infor-mation as well as appendix X should be reviewed and understoodbefore an expansion joint is used in a design.

36A3.6.2 Resilient Supports Spring supports discussed inpara. 321.2.3 are an important part of supporting piping systemswhen there are significant movements in the vertical direction.Sometimes very small vertical movements can be significant if theuser is trying to protect equipment from thermal expansion loads.Other times, a piping system may run vertically for long distances.This makes it very difficult to distribute the piping loads withoutthe use of spring supports. References 14, 15, and 21 provideexcellent guidance on how to design supports to meet the require-ments in this section.

36A3.7 SystemsThe design section in the Code refers to specific systems, some

of which are covered here. Because ASME B31.3 is the mostgeneric of the Pressure Piping Series, no attempt is made to coverall of the possible systems. Instead, only Instrumentation, Pres -sure Relief Systems and Pressure Relief Discharge Piping areaddressed.

Instrumentation piping is included because of a frequent mis-understanding it is not covered by the piping Code. If the instru-ment is in line, or the tubing is part of the piping system pressureboundary, the instrument piping is included in the scope of theCode. This also applies to the air or hydraulic fluid used to oper-ate valves or control apparatus.

Pressure Relieving Systems receive special attention because oftheir importance in maintaining the piping system within thedesign pressure.

Pressure Relief Discharge Piping has unusual design considera-tions which are briefly discussed.

Pressure Relief Devices are designed to ASME BPV CodeSection VIII Div 1 and appropriate sections of ASME BPV CodeSection VIII Div 1 are referenced in this section.

36A4 MATERIALS

Chapter III of the Code addresses limitations on materialsused for Code construction. For the most part, the Code pro-vides an extensive list of acceptable materials and limitationsfor the use of these materials as part of Appendix A. Appendix Aand its organization will be described in more detail later in thischapter. After providing a brief set of requirements for the useof materials not listed in Appendix A, the rest of the 10 pagechapter is really devoted to the use of materials at the lowertemperature limit. The object of all of these requirements iseither to make sure the material and any welds to the material


PROPRIETARY A

SME

are tough enough so they will not fail in a brittle manor. Thisseems to be a very difficult concept to describe clearly andresults in a significant amount of the inquiries submitted to theCode. The ASME has all of the published interpretations postedon their web site and if the user has trouble understanding therequirements, the published interpretations on the subject mightbe worth the time to review them. ASME B31T has also re-cently been published to provide a little clearer approach to thissame subject.

Material toughness is affected by:

Material PropertiesMaterial ThicknessTemperatureWeldingStress level

When determining the adequacy of a material for low tempera-ture service, the first step should always be to determine if thematerial will be used below the minimum temperature listed forthe material in Appendix A. This is either listed as a temperaturelimit or a letter designation, the letter designation is a reference toFigure 323.2.2A or Table 323.2.2A. Both the table and figure pro-vide a Design Minimum Temperature which varies with theNomi nal Thickness of the material.

Additional requirements for impact testing may still berequired if the material is to be used below -29�C (-20�F). Theserequirements are identified in Table 323.2.2. This table also pro-vides additional requirements or exceptions if the material did notmeet the requirements above.

Some relief is provided in Para. 323.2.2(d)(1), however therequirements/exemptions in this paragraph are only applicableabove -48�C (-55�F).

For temperatures between -48�C (-55�F) and -104�C (-155�F)Para. 323.2.2(d)(2) provides one more possibility for relief fromimpact testing if the material stress ratio defined in Fig 323.2.2Bis below 0.3.

The requirements for additional impact testing in the Codeapply in addition to those in ASME B&PV Code Section IX. Thisis because the Code requirements for low temperature service arespecific to the service temperatures not addressed by the weldingrequirements in Section IX. If the user has any doubts on therequirements associated with low temperature service, an experi-enced welding or metallurgical engineer should be consulted to besure the requirements in this chapter of the Code are being cor-rectly implemented. ASME B31T and reference 16 provide addi-tional information on this topic.

36A5 STANDARDS FOR PIPINGCOMPONENTS

Standard components were discussed in paragraph 36A3.3.1with the discussion and Table 36A3.3.1 giving examples of howcomponent standards work together to provide dimensional andpressure temperature ratings. Chapter IV, Table 326.1 (repeatedbelow as Table 36A5) provides a list of acceptable standards forCode construction. The user is cautioned while these standardsare acceptable they are only acceptable within the limits providedin the reference standard and in some cases additional limitationsof the Code. Chapter IV of the code provides requirements/responsibilities so the user can qualify unlisted components forCode use. See reference 7 for additional guidance.

36A6 FABRICATION, ASSEMBLY ANDERECTION

36A6.1 Welding, Preheating and Post Weld HeatTreat

This is Chapter V in the Code and it addresses Welding re -quirements and Welding Qualification. Many of the weldingrequirements are referenced back to ASME B&PV Code SectionIX . As was noted earlier, because the Code has specific servicerequirements, the requirements in ASME B31.3 should be appliedin addition to the requirements of ASME B&PV Code Section IX.Some of the differences between the various Codes are not associ-ated with service requirements, a significant effort is being madeto minimize these differences and this continues to be an ongoingeffort by committee members.

36A6.1.1 Welding Procedure Specification (WPS) A WPS isa written welding procedure for making production welds to speci-fied requirements. The WPS or other document is used to capture theessential variables of a welding procedure which will be qualified bydestructive testing, then provide direction to the welder or weldingoperator to production welds have comparable properties.

Procedure Qualification Record(s) (PQR) provide documenta-tion of the testing required to qualify a procedure. The ASMEBoiler and Pressure Vessel Code Section IX, QW-482 gives a sug-gested format for Welding Procedure Specifications (WPS).

36A6.1.2 Welder Performance Qualification The manufac-turer or contractor is responsible for conducting tests to qualifywelders and welding operators in accordance with qualified weld-ing procedure specifications. The purpose of welder and weldingoperator qualification tests is to ensure that the welder(s) andwelding operator(s) following the procedures are capable ofdeveloping the minimum requirements specified for an acceptableweldment. Performance qualification tests are intended to deter-mine the ability of welders and welding operators to make soundwelds.

36A6.2 PreheatingPreheating requirements are provided in Para. 330 of the Code.

Preheating is used, along with heat treatment, to minimize thedetrimental effects of high temperature and severe thermal gradi-ents in welding and to drive out hydrogen that could cause weldcracking, and improve metallurgical properties. The effect ofreducing hydrogen cracking is accomplished by a variety of fac-tors, including driving off moisture, reducing the cooling rate, andincreasing the rate of hydrogen diffusion in the material.

The preheat requirements, which are applicable to all types ofwelding including tack welds, repair welds, and seal welds ofthreaded joints, are provided in Table 330.1.1.

36A6.3 Heat TreatmentPost–weld heat treatment is performed to temper the weldment,

relax residual stresses, and remove hydrogen. The consequentialbenefits are avoidance of hydrogen-induced cracking andimproved ductility, toughness, corrosion resistance, and dimen-sional stability.

Heat treatment requirements are provided in para. 331 ofASME B31.3. The Code requires heat treatment after certainwelding, bending, and forming operations. Specific requirementsfor post-weld heat treatment are provided in Table 331.1.1.

36-8 • Chapter 36

PROPRIETARY A

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TABLE 36A5 COMPONENT STANDARDS (Source: Table 326.1 of ASME B31.3, 2010)

PROPRIETARY A

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36-10 • Chapter 36

TABLE 36A5 (CONTINUED)

PROPRIETARY A

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Brinell hardness testing after the heat treatment is performed isrequired for low alloy steel as a means of quality control, toensure that the metal has been properly tempered. See 331.1.7when hardness values are provided in Table 331.1.1.

ASME B31.3, Para. 331.2, permits exceptions to the heat treat-ment requirements of Table 331.1.1 where warranted based onknowledge or experience of the service conditions. Normalizing,or normalizing and tempering, or annealing may be used in lieu ofthe heat treatment of Table 331.1.1 provided the material proper-ties of the weld and base material meet the specification require-ments after heat treatment. This requires approval of the designerand if less-stringent, the designer must demonstrate to the ownerit is adequate. The WPS must also be developed and qualifiedwith the same heat treatment, or lack thereof.

36A6.3.1 Governing Thickness for Heat Treatmen Whenusing Table 331.1.1, the thickness to be used is generally the thick-er of the two components, measured at the joint, that are beingjoined by welding. For example, if a pipe is welded to a heavier wallvalve, but the valve thickness is tapered to the pipe thickness at thewelded joint, the governing thickness will be the greater of the valvethickness at the end of the taper at the weld joint (presumably thenominal pipe wall thickness) or the pipe thickness. Two specialcases are branch connections and fillet weld joints. For branch con-nections, it is the thickness of the weld that is considered. Only halfof the thickness of the weld is used as the governing thickness (or,as stated in the Code, the thickness through the weld is compared totwice the minimum material thickness requiring heat treatment inTable 331.1.1). This includes the dimension through the penetrationweld joining the run and branch pipe and reinforcement, if any, aswell as the cover fillet weld. Specific guidance for determining theweld thickness is provided in para. 331.1.3(a). Note that for thecover fillet, the throat dimension is used.

It is actually required to also consider the thickness of the partsjoined by welding in branch connections as well as the weldmetal; however, metal added as reinforcement, whether an inte-gral part of a branch fitting or attached by welding, need not beconsidered. Since branch connections are required by the Code tobe full-penetration welded, it is unlikely that a circumstance willarise where the base material is thicker than the weldment. Forexample, while integrally reinforced branch connection fittingsoften have substantial thickness, the weld size would govern sincethe additional thickness of the fitting is entirely reinforcement.

For fillet welds at slip-on and socket weld joints DN 50 (NPS2) and smaller, for seal welding of threaded joints in piping DN50 (NPS 2) and smaller, and for attachment of external non-pressureparts such as lugs, the heat treatment is based on the larger ofeither the thickness through the weld or the thickness of the partsthat are joined by the weld, with certain exceptions. As withbranch connections, when evaluating the weld, it is based on halfof the thickness (or the thickness through the weld is compared totwice the thickness in Table 331.1.1). For larger pipe, only thebase material thickness, not the weld thickness, is considered. The exceptions permit consideration of the weld only, neglectingthe base material thickness. These exceptions, which exempt cer-tain fillet welds from heat treatment are covered in Para. 331.1.3.

36A6.4 Pipe Bends Pipe may be hot or cold bent (Reference Para. 332.2). For cold

bending of ferritic materials, the temperature must be below thetransformation range. For hot bending, the temperature must beabove the transformation range. The thickness after bending must

comply with the design requirements. See reference 21 for addi-tional information on pipe bending.

36A6.5 Brazing and Soldering Brazing procedures, brazers, and brazing operators are required

to be qualified in accordance with ASME B&PV Code, SectionIX, Part QB. An exception is for piping in Category D fluid ser-vice with a design temperature not exceeding 93_C (200_F); forthis condition, the owner can waive the requirements for suchqualifications.

Solderers are required to follow the procedures in the CopperTube Handbook of the Copper Development Association. See ref-erence 24 at the end of the chapter.

Aside from these requirements, general good practice require-ments for brazing and soldering are specified in para. 333 ofASME B31.3.

36A6.6 Welded Joint DetailsWelded joint details, including socket weld joints, socket weld

and slip-on flanges, and branch connections are provided inChapter V. Standard details for slip-on and socket welding flangeattachment welds are provided in Fig. 328.5.2B.

A couple of points worth noting are the fillet weld size, whichis 1.4 times the nominal pipe wall thickness (or the thickness ofthe hub, whichever is less), and the small gap shown between theflanges face and the toe of the inside fillet for slip-on flanges. Thesmall gap is intended to avoid damage to the flange face due towelding. It indicates a gap, but there is no specific limit. This dif-fers from Section VIII, Division 1, which specify the gap to be1/4.”

The question arose as to whether a specific limit to the gapbetween the fillet weld and flange face was appropriate. Studies,including finite element analysis and earlier Markl fatigue testing,indicated that it essentially did not matter how much the pipe wasinserted into the flange. Insertion by an amount equal to the hubheight was optimal for fatigue life, but there was not a significantdifference. To minimize future confusion, inclusion of minimuminsertion depth has been recommended and may be specified in afuture edition of B31.3. Reference 12 provides a more detailedevaluation on fillet welds and insertion depth effect on a joint.

The required fillet weld size for socket welds other than socketweld flange is specified in Fig. 328.5.2C which is shown in figure36A6.6 below.

The specified fillet weld was recently revised to be tied to thenominal wall of the pipe instead of a calculated wall which wasimpractical.

A second issue with this figure which has caused considerablecontroversy is the 1.5 mm (1/16 in.) approx. gap before welding.This is a requirement for a gap before welding, so that weldshrinkage will be less likely to cause small cracks in the root ofthe fillet weld. The user can find a number of interpretations onthis subject on the ASME web site, but the fillet weld should beacceptable if it did not crack. There is no Code requirement for agap after it has been welded.

36A6.7 Assembly and ErectionSome of the requirements in this section are included to make

sure assumptions back in the analysis and design requirementsremain valid during construction. When piping does not fit, sig-nificant stresses can be developed if it is forced into position. Thisis essentially cold springing the piping, only it was not specified


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in the design, or if cold springing was specified to be sure it prop-erly incorporated in the construction.

36A6.7.1 Bolted Joints Proper assembly of bolted joints isessential to avoid leakage during service. This includes not onlyvisible leaks, but also minimizing fugitive emissions, which are animportant consideration in the United States as a result of environ-mental regulations. Information on flange bolting is provided inAppendix S of Section VIII, Division 1. An ASME guideline onflange bolt-up procedures, PCC-1, Guidelines for PressureBoundary Bolted Flange Joint Assembly, 2010 is listed as refer-ence 22 at the end of the chapter.

ASME B31.3 provides some good practice with respect toflange bolt-up in para. 335. This includes requiring repair orreplacement of flanges with damaged gasket seating surfaces, uni-formly compressing the gasket during flange bolt-up, and use ofonly one gasket between seating surfaces.

36A6.7.2 Other Joints Used for Assembly Threaded, expanded,caulked, compression, tubing and other special joints are alsoaddressed briefly in this section. If any of these joints are used thissection has some simple requirements and considerations.

36A7 INSPECTION, EXAMINATION, ANDTESTING

36A7.1 InspectionThis can be thought of as more of a Quality assurance function.

The owner’s Inspector oversees the work performed by the exam-iner. It is the Inspector’s responsibility to verify that all therequired examinations have been completed and to inspect thepiping to the extent necessary to be satisfied that it complies withall of the applicable examination requirements of the Code and ofthe engineering design. Note that the process of inspection does

not relieve the manufacturer, fabricator, or erector of their respon-sibilities for complying with the Code. The owner’s Inspector isalso required to be qualified to perform the work, see para. 340.4

The owner’s Inspector may be an employee of the owner, or anemployee of an engineering or scientific organization, or of a rec-ognized insurance or inspection company, acting as the owner’sagent. Some limits apply to avoid a conflict of interest for theinspector(s).

36A7.2 ExaminationOverview of Examination Requirements.ASME B31.3 requires that examination of the piping be per-

formed by the piping manufacturer, fabricator, and/or erector as aquality control function. These examinations include a number ofdifferent methods based on the type of material or fabrication.

The examiner is required to be an individual that is qualified toperform the examination work. They are required to have trainingand experience commensurate with the needs of the specifiedexamination, with records of such qualifications maintained bytheir employer. While there are no specific requirements, ASMEB31.3 refers to SNT-TC-1A, Recommended Practice for Non -destructive Testing Personnel Qualification and Certification, asan acceptable guide.

Requirements for the examination processes are described inSection V of the Boiler and Pressure Vessel Code, with limitedexceptions and additions. The required degree of examination andthe acceptance criteria for the examinations are provided inChapter VI of ASME B31.3. The examiner is required to have awritten procedure for their examination work (para. 343).

36A7.2.1 Progressive Examination ASME B31.3 includes theconcept of progressive examination in para. 341.3.4. The conceptapplies to all random examinations the items to be examined areseparated into lots. Pipe Fabrication Institute, PFI ES-48, RandomExamination provides some guidance on how “lots” can be selected,see reference 23. Some percent (e.g., 5% of girth welds for normalfluid service) of the items are selected at random and examined.For each item found to be defective, two more are selected fromthe same lot and given the same type of examination. This progres-sion continues until a point where no defects are found, or the “lot”of welds have enough defects that 100% examination is required.

Lots provide an opportunity for the organization to balance anumber of different quality control concepts.

Too large a lot size would leave the owner vulnerable to 100%examination of a large quantity of welds based on a localizedproblem.

If the 5% examination requirement is completed too soon, thewelders/contractor might take short cuts knowing no more of theirwelds would be examined.

A lot where no welds are examined until the end of the projectwould leave the project exposed to a quality problem which couldhave been corrected early in a project.

Progressive examination has proved to be an effective tool forverification of quality control, however it must be applied withsome experience to be sure it is a cost effective method of verify-ing weld quality. A number of inquiries/interpretations have beenissued because defects were found after the piping was examinedin accordance with the Code requirements. These should bereviewed prior to writing construction or fabrication contracts tobe sure additional requirements which might be warranted for aspecific service is adequately addressed.

36-12 • Chapter 36

FIG. 36A6.6 MINIMUM WELDING DIMENSIONS FOR SOCKETWELDING COMPONENTS OTHER THAN FLANGES (Source:Fig. 328.5.2C of ASME B31.3-2010)

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36A7.2.2 Types of Examination Visual examination (VT)means using the unaided eye (except for corrective lenses) toinspect the exterior and readily accessible internal surface areas ofpiping assemblies or components. It does not include nor requireremote examination such as by the use of boroscopes. Visualexamination is used to check materials and components for confor-mance to specifications and freedom from defects; fabricationincluding welds; assembly of threaded, bolted, and other joints;piping during erection; and piping after erection.

Radiographic examination (RT) means using x-ray or gam-maray radiation to produce a picture of the subject part, includingsubsurface features, on radiographic film for subsequent interpre-tation. It is a volumetric examination procedure that provides ameans of detecting defects that are not observable on the surfaceof the material. Requirements for radiographic examination ofwelds are provided in Section V, Article 2.

Ultrasonic examination (UT) means detecting defects usinghigh-frequency sound impulses. The defects are detected by thereflection of sound waves from them. Ultrasonic examination isalso a volumetric examination method that can be used to detectsubsurface defects. It can be used as an alternative to radiographyfor weld examination. The requirements for ultrasonic examina-tion of welds are provided in Section V, Article 4, with an alterna-tive for basic calibration blocks provided in para. 344.6 ASMEB31.3. The acceptance criteria for ultrasonic examination aregiven in para. 344.6.2.

In-process examination is a visual examination of the entirejoining process, as described in para. 344.7 ASME B31.3. It isapplicable to welding and brazing for metals and bonding for non-metals. Since radiographic examination is not considered to pro-vide useful results in brazing and bonding, in-process examinationis used for these instead of radiography. For welding, it is permit-ted as a substitute for radiographic examination if specified in theengineering design or specifically authorized by the Inspector.

Liquid-penetrant examination (PT) means detecting surfacedefects by spreading a liquid dye penetrant on the surface, remov-ing the dye after sufficient time has passed for the dye to penetrateinto any surface defect, and applying a thin coat of developer to thesurface, which draws the dye from defects. The defects are observ-able by the contrast between the color of the dye penetrant and thecolor of the developer. Liquid-penetrant examination is used for thedetection of surface defects. It is used in the examination of socketwelds and branch connections in severe cyclic service that cannotbe radiographed; and for the examination of all welds, includingstructural attachment welds, that are not radiographed when thealternative leak test (ASME B31.3, para. 345.9) is used. Liquidpenetrant examinations can cause problems for vacuum jacket pip-ing because it is difficult to evacuate the jacketed area after theexamination because the liquid penetrant continues to off gas.

Magnetic-particle examination (MT) employs either electriccoils wound around the part or prods to create a magnetic field. Amagnetic powder is applied to the surface and defects are revealedby patterns that the powder forms in response to the magneticfield disturbances caused by defects. This technique reveals sur-face and shallow subsurface defects. As such, it can provide moreinformation than liquid-penetrant examination. However, its use islimited to magnetic materials. Magnetic-particle examination isan alternative to liquid-penetrant examination wherever such anexamination is required in ASME B31.3 (except in the case ofmetallic bellows). The requirements for magnetic-particle exami-nation of welds and components other than castings are providedin Section V, Article 7.

Hardness testing is required after heat treatment under somecir cumstances, as specified in Table 331.1.1 of ASME B31.3.Hard ness testing is not required for carbon steel (P-1), ferritic andaustenitic stainless steel (P-7, P-8), high nickel alloys (P-9A, P-9B), as well as some less commonly used alloys. It is requiredin some circumstances for low and intermediate alloy steels. Forwelds, the hardness check includes both the weld and the heataffected zone. It is a quality control procedure to make sure thatthe heat treatment was effective.

ASME BPV Code Section V provides many of the examinationrequirements and procedures which are used in the Code.

36A7.2.3 Required Examination The required examinationdepends on the category of fluid service. Different degrees ofexamination are required for Category D, Normal, and Category Mfluid services. More examination is required for more hazardous orsevere services.

36A7.3 Testing Pressure Testing

36A7.3.1 Overview of Pressure Test Requirements ASMEB31.3 requires leak testing of all piping systems with a few excep-tions (based on the hazard, or service and with “owners” approval).The various options for leak testing are noted below. The hydrotestis the primary method, but there are a number of places where ahydrotest is not practical and the other tests can be used within thelimits provided in this section of the Code.

(1) hydrostatic test,(2) pneumatic test,(3) hydropneumatic test, and(4) alternative leak test.

The leak test is required to be conducted after any heat treat-ment has been completed.

36A7.3.2 Hydrostatic Test A hydrostatic test is the safest test,so it is conducted at a higher pressure, this has beneficial effectssuch as crack blunting and warm prestressing. These reduce therisk of crack growth and brittle fracture after the hydrotest whenthe pipe is placed in service. The test is generally conducted at apressure of 1.5 times the design pressure times a temperature cor-rection factor. The temperature correction factor compensates forthe fact that the test may be conducted at a lower temperaturethan the system will be design for. This correction factor is anattempt to stress the material to a level higher than it will experi-ence during operation. Reference equation (24), para. 345.4.2. Anumber of exceptions are provided to this requirement so thehigher pressure does not over pressurize any components orattached equipment.

36A7.3.3 Pneumatic Test A pneumatic test is more hazardousdue to the amount of stored energy in the compressed gas. A rupturecould result in an explosive release of this energy. It is also more dif-ficult to locate leaks associated with a pneumatic leak test. The tem-perature correction factor is not applied to pneumatic testing andadditional rules permit the reduction of test pressure while the weldsare being examined.

36A7.3.4 Alternative Leak Test An alternative leak test is per-mitted, with the owner’s approval, when neither a hydrostatic norpneumatic leak test would be possible or safe. Para. 345.9 of the


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Code has the requirements associated with the use of an AlternateLeak Test.

36A7.3.5 Sensitive Leak Test A sensitive leak test is arequired part of an alternative leak test and is also required forCategory M fluid service piping. This is a test performed at lowpressures to test for leaks. Methods for performing this type of testare described in Section V, Article 10.

36A7.3.6 Jacketed and Vacuum Piping Piping that isdesigned for external-pressure condition is generally tested withinternal pressure. The test pressure is required to be the greater of1.5 times the design differential pressure or 105 kPa (15 psi).Jacketed or other double-wall piping requires leak testing of boththe inner pipe and the jacket. The jacket is tested as normal pipingbased on its design pressure, unless otherwise specified in theengineering design. The inner pipe is normally designed to carrythe jacket pressure with no internal pipe pressure, without buck-ling.

The requirement that all joints be visually observed during aleak test can be problematic for jacketed or double containmentpiping. Code Case 180 provides some relief in the form of alter-native rules.

36A7.3.7 Initial Service Leak Test For piping in Category Dfluid service, ASME B31.3 permits an initial service leak test inlieu of other leak tests such as hydrostatic or pneumatic. In thistest, the system is pressurized with the process fluid and the jointsare inspected for leaks.

36A7.3.8 Closure Welds In the 1996 edition, addenda c(1998), closure welds were added [para. 345.2.3(c)] as an accept-able exemption from leak testing. A closure weld is a final weldconnecting piping system or component that has been success-fully leak tested. The closure weld does not require leak testing ifit passes 100% radiographic or ultrasonic examination and is in-process examined.

While the Code does not address existing piping, closure weldsare an important tool to connect new piping construction to anexisting system.

36A8 NONMETALLIC PIPING ANDPIPING LINED WITH NONMETALS

The user is cautioned the Non-metallic industry is not as standard-ized as steel and other metal products, as a result the compliance withsupplier requirements and recommendations is important with mostnonmetallic piping materials and components.

The rules for nonmetallic piping and piping lined with non-metals are located in Chapter VII of ASME B31.3. These paragraphs follow the same paragraph numbering of the baseCode, Chapters I through VI, but start with the letter A. If require-ments located elsewhere in the Code apply to these piping sys-tems, they are referenced from a paragraph in Chapter VII. Thebehavior of nonmetallic piping is different than metallic piping,and the design criteria are significantly less well developed.Supplemental rules are also provided for nonmetallic lining ofmetallic piping.

References 18 and 19 provide background on Chapter VII.ASME BPV Code Section X, ASME RTP-1 Reinforced ThermosetPlastic Corrosion-Resistant Equipment (Reference 32) and WRC

415 (Reference 20) provide a lot of information on Reinforced-Thermosetting Resin design and component standards.

36A8.1 Allowable StressVarious nonmetals have different, established methods of deter-

mining allowable stresses. Some limited allowable stress valuesare provided in Appendix B for thermoplastic and reinforced ther-mosetting resin pipe. For the most part, allowable stresses or pres-sure ratings must be determined from tests performed by themanufacturer.

36A8.2 Pressure DesignThe philosophy of the base Code with respect to metallic pip-

ing applies to nonmetallic piping. The primary differences are thatthe table of listed components for nonmetallic piping is TableA326.1 rather than Table 326.1, and the pressure design equationsare slightly different than the base Code.

Listed components with established ratings are accepted atthose ratings. Listed components without established ratings, butwith allowable stresses listed, can be rated using the pressuredesign rules of A304; however, these are very limited. In the casesof listed components without allowable stresses or unlisted com-ponents, components must be rated per para. A304.7.2. Manytimes this may be done by the manufacturer, however the designeris still responsible for verifying the manufactures qualificationmeet the requirements of the Code.

The equations that are available for sizing nonmetallic compo-nents are very limited in this chapter. These equations relate tostraight pipe, flanges, and blind flanges. The use of the referencedflange design method (per Section VIII, Division 1, Appendix 2 isquestionable for many nonmetallics. As a result, for pressuredesign most nonmetallic piping components must be either per alisted standard (i.e., listed in Table A326.1) or qualified perParagraph A304.7.2.

36A8.3 Limitations on Components and JointsFluid service requirements for nonmetallic piping components

are covered in Part 3 of Chapter VII. Fluid service requirements fornonmetallic piping joints are covered in Part 4 of Chapter VII. Forthe most part, the requirements are similar to the base Coderequirements, with relevant paragraphs on nonmetallic componentsand joints substituted for paragraphs on their metallic counterparts.

36A8.4 Flexibility and SupportRules regarding flexibility and support for nonmetallic piping

are provided in Part 5 of Chapter VII. ASME B31.3. This sectiondoes not provide detailed rules for evaluation of nonmetallic pip-ing systems for thermal expansion. However, it requires a formalflexibility analysis when the listed exemptions from formal flexi-bility analysis are not met. Probably the most important exemptionis to employ joining methods or expansion joint devices, in accor-dance with the manufacturer’s instructions and recommendations.

One of the significant differences from metallic systems is thatfully restrained designs are commonly used. That is, systemswhere the thermal expansion is offset by elastic compression/extension of the piping between axial restraints. This is possiblebecause of the relatively low elastic modulus of plastic piping.The resulting loads are generally reasonable for the design ofstructural anchors. Note, however, in performing a computer flexi-bility analysis of such systems, the axial load component of ther-mal expansion stress must be included.

36-14 • Chapter 36

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A lot of other warnings or requirements are included in thissection and should be reviewed before any nonmetallic piping isdesigned or analyzed.

36A8.5 MaterialsThermoplastic materials may only be used for flammable fluid

service when they are underground. In any use other than CategoryD fluid service, thermoplastic piping is required to be safeguarded.Poly(vinyl chloride) (PVC) and Chlorinated poly(vinyl chloride)(CPVC) are prohibited from compressed air or other compressed-gas service due to the potential for brittle failure.

Reinforced Plastic Mortar (RPM) piping is required to be safe-guarded when used in other than Category D fluid service.

Reinforced Thermosetting Resin (RTR) piping may be used intoxic or flammable fluid service, but requires safeguarding. It isgenerally acceptable for other services, subject to suitability ofthe material.

Borosilicate glass and porcelain are brittle materials and arelimited in the services where they can be used.

Recommended maximum and minimum temperatures are gen-erally provided. If a material is to be used at a temperature belowthe minimum temperature listed in Appendix B, the designer musthave some test results at or below the lowest use temperature thatensure that the materials and bonds will have adequate toughnessand are suitable at the design minimum temperature. Unlike metallic materials, specific tests such as Charpy are not specified.

36A8.6 Bonding of PlasticsOne of the key elements to successful construction of a plastic

piping system is the joints. ASME B31.3 requires a formalprocess of developing, documenting, and qualifying bonding pro-cedures and personnel performing the bonding. The joints in plas-tic (RTR, RPM, and thermoplastic) piping are called bonds. Therequirements are similar to the requirements for qualification ofwelds and welders in the base Code for metals.

The first step is to have a documented bonding procedure speci-fication (BPS). The specification must document the proceduresfor making the joint, as set forth in para. A328.2.1. This proce-dure must be qualified by a bonding procedure qualification test.

Once it is so qualified, it may be used by personnel to bondnonmetallic ASME B31.3 piping systems. Those bonders, how-ever, must also be qualified to perform the work. Bonders arequalified in a performance qualification test. The qualification testfor the bonding procedure and the bonder are the same. Also sim-ilar to welding, if the bonder has not used the procedure for aperiod of time, they must be requalified. While this may seem likea lot for a procedure which seems to require a lot less skill thanwelding, many of the problems associated with nonmetallic pip-ing are the result of not understanding or following the correctbonding procedures.

Under some circumstances, it is not possible to pass a qualifica-tion test using the hydrostatic test method because the compo-nents fail at a pressure that is lower than the test pressure; thus, itis not possible to test the joint at the test pressure. In this circum-stance, the burst test method should be used. With the burst testmethod, it is only necessary to demonstrate that the joint isstronger than the weakest component; i.e., the criterion is thatfailure initiates outside of any bonded joint.

Welding of metallic piping lined with nonmetals generally fol-lows the base Code requirements for welding of metallic piping.Precautions are provided in para. A329. For example, precautions

are required to avoid damage to the nonmetallic lining. If suchdamage occurs, it must be repaired. Qualification of a welder orwelding operator for a WPS for lined pipe is specific to the lining;a different qualification test is required for each lining material.This, of course, only applies to pipe that has already been lined,not welding of piping prior to lining it.

36A8.7 Examination and TestingThe nondestructive examination techniques for nonmetallic

piping are not nearly as well developed as for metallic piping. Asa result, the techniques that are used are visual and in-processexamination or specific to the manufacture of the components.

36A8.8 Requirements for Leak Testing NonmetallicPiping

The leak test rules in the base Code, described in the prior para-graphs, are generally applicable to nonmetallic piping, with a fewexceptions. The hydrotest pressure for nonmetallics other than ther-moplastics (e.g., RTR, fiberglass pipe) and metallic piping linedwith nonmetals are 1.5 times the design pressure, but not more than1.5 times the maximum rated pressure of the lowest-rated compo-nent in the system. There is no temperature correction factor. It isparticularly important not to overpressure fiber glass piping systems.Excessive hydrotest pressures in fiberglass systems have causedsubsequent failures in service. The overload condition can damagethe material without evidence of a leak during the test itself.

The following warning is not included in the code at this time,however it should be considered when working with nonmetallicpiping. During pressurizing and particularly during pressure test,nonmetallic piping will elongate (if not restrained) significantlymore than metallic piping. This can cause the piping to jump ormove significantly during a failure of a joint during hydrotestingof long runs of piping. Additional safety precautions should betaken to protect personnel while the piping is pressurized to 1.5times the design pressure.

The alternative leak test is not permitted for nonmetallic piping.

36A9 CATEGORY M FLUID SERVICE

When to Use the Rules for Category M Fluid Service:The rules in Chapter VIII of ASME B31.3 are used when the

owner designates a piping system to be in Category M fluid ser-vice. The owner is guided in the classification for the piping sys-tem by the definition of Category M fluid service in Chapter I ofASME B31.3. This definition is the Code rule relative to classifi-cation. A guide to the application of these rules is provided inAppendix M, which contains a flow chart to assist the owner inclassifying fluid services.

All criteria must be satisfied for the service to meet the defini-tion of Category M.

Note that the Code considers many very hazardous fluid ser-vices to be normal fluid service. The design and construction rulesfor normal fluid service are suitable for hazardous services.Category M provides a higher level. If higher integrity piping isdesired by the owner, even though the fluid does not meet the def-inition of Category M, the owner can still specify the additionaldesign, construction, examination, and testing requirements thatare provided in Chapter VIII.

Hydrofluoric acid is one example of a fluid for which manyowners specify more stringent requirements than are provided in


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the Code for normal fluid service, although it would be consid-ered normal fluid service.

A key part of the definition often neglected, are the words “inwhich the potential for personnel exposure is judged to be signifi-cant.” A piping system for which the potential for the exposure ofpersonnel to the fluid is judged to be insignificant would not sat-isfy the definition of Category M.

Another consideration that is often missed is that the definitionrequires the fluid to be toxic. Dangerous fluids are not necessarilyCategory M. According to the definition, exposure to a very smallquantity is required to cause serious irreversible harm. Thus, thepresence of H2S in the system would not necessarily make itCategory M Fluid Service.

Examples of systems for which personnel exposure may bejudged to be insignificant include double-containment piping withleak detection and piping systems that people may not be exposedto by virtue of isolation or other means of personnel protection. Assuch, chemicals such as phosgene and MIC, which may be classi-fied as Category M in a single-wall piping system, may be classi-fied as normal fluid service in a double-containment piping system.

Another key consideration is that only the owner has the rightand responsibility to select the fluid service.

36A9.1 Organization of Chapter VIIIChapter VIII follows the same paragraph numbering as the

base Code, Chapters I through VI. However, the paragraphs startwith M for metallic piping in accordance with Chapter VIII andMA of nonmetallic piping in accordance with Chapter VIII.

To determine the rules for piping systems in Category M fluidservice, simply refer to Chapter VIII. If rules elsewhere in theCode apply, they will be referred to in Chapter VIII. In general,Chapter VIII refers to the base Code for metallic piping andChapter VII for nonmetallic piping.

Chapter VIII makes no provision for severe cyclic conditions,as stated in para. M300(e). Severe cyclic conditions should beavoided by design in these systems. This simply requires, for sys-tems with greater than 7,000 equivalent cycles, the inclusion ofenough flexibility to reduce the thermal expansion stress range to80% or less than the allowable. If, for some reason, this is not fea-sible, ASME B31.3 requires that the engineering design specifyany necessary provisions.

36A9.2 Overview of Metallic RulesThe metallic rules prohibit the use of certain components con-

sidered to have lower integrity, and they require additional designconsiderations, additional examination, and additional testing.The measures are intended to result in a piping system that is lesslikely to leak. The following are highlights of some of theserequirements. It is not an all-inclusive list; refer to ASME B31.3for the complete requirements.

(1) The presumptive degree of ambient cooling (e.g., 5% foruninsulated pipe) provided in the base Code is not permit-ted. Rather, the design metal temperature, if less than thefluid temperature, must be substantiated by heat transfer cal-culations confirmed by tests or by experimental measures.

(2) Increased pressure temperatures for short-term variations(allowances for variations) are not permitted.

(3) Lower integrity piping and components are prohibited.(4) Special consideration is required for prevention of valve

stem leakage to the environment. Specific requirements are

provided for valve bonnet or cover plate closures.(M307.2)

(5) Single-welded slip-on, expanded-joint, and threaded (withcertain exceptions) joint flanges are prohibited. (M308.2)

(6) Expanded joints are prohibited. (M313)(7) Additional limitations are provided for threaded joints.

(M314)(8) Joints such as caulked (M316), soldered and brazed

(M317), and bell-type joints (M318) are prohibited.(9) Pipe supports are required to be constructed of listed mate-

rials. (M321)(10) Specific provisions for instrument piping [e.g., limiting

tubing to 16 mm (5/8 in.) diameter maximum, accessibleblock valves required to be available to isolate the instru-ment piping from pipeline]. (M322.3)

(11) The design pressure is not permitted to be exceeded bymore than 10% during pressure relief. (M322.6.3)

(12) The low-stress exemption from impact testing is not per-mitted. (M323.2)

(13) Cast iron and ductile iron are not permitted for pressurecontaining parts, and lead and tin may only be used as lin-ings. (M322.4.2)

(14) Less-stringent heat treatments than required in Table331.1.1 are not permitted. (M331)

(15) Additional examination is required. While the acceptance criteria of the base Code are applicable, the amount of radiog-raphy is increased from 5% to 20% and random visual exam-ination is generally increased to 100% visual examination.

(16) In addition to the testing required for normal fluid service,an additional sensitive leak test is required to ensure pipingis free from small leaks.

36A9.3 Overview of Nonmetallic RulesThe nonmetallic rules prohibit the use of certain components con-

sidered to have lower integrity, and they require additional designconsiderations, additional examination, and additional testing. Themeasures are intended to result in a piping system that is less likely toleak. These rules generally refer to Chapter VII. The following arehighlights of some of these requirements. It is not an all-inclusive list; refer to ASME B31.3 for the complete requirements.

(1) The piping is not permitted to exceed the design pressureunder any circumstance, including pressure-relief condi-tions. This is the same as the rule for nonmetallic piping.(MA 302.2.4)

(2) Nonmetallic fabricated branch connections are prohibited.(MA 306.5)

(3) Nonmetallic valves and specialty components are prohibited.(MA 307)

(4) Hot-gas–welded, heat-fusion, solvent-cemented, and adhe-sive bonded joints are not permitted except in linings.(MA311.2)

(5) Expanded, nonmetallic threaded, and caulked joints areprohibited. (MA313, MA314, MA316)

(6) Thermoplastics and reinforced plastic mortar are permittedonly as linings and, for thermoplastics, gaskets.(MA323.4.2)

(7) The examination and testing rules of Chapter VII applyexcept that 100% visual examination of all fabrication aswell as bolted and mechanical joints is required and in-process examination is increased from 5% to 20%.

36-16 • Chapter 36

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36A9.4 General CommentsThe rules of Chapter VIII are intended to provide greater assur-

ance of leak tightness. An example is the requirement that a sensi-tive leak test be performed in addition to the standard leak test(e.g., hydrotest). The ASME B31.3 Section Committee does notgenerally spend a great deal of time on this section. However, therules may not be sufficient for the extremely dangerous chemicalsthat fit the definition of Category M. Additional precautions shouldbe considered, such as 100% radiography or double containment.

36A10 HIGH PRESSURE PIPING

36A10.1 Scope of Chapter IX, High-Pressure PipingChapter IX of ASME B31.3 only applies when the owner speci-

fies its use. It applies to piping in high-pressure fluid service. Notethat the definition of high-pressure fluid service simply requiresthat the owner specify use of Chapter IX. Some guidance is pro-vided in K300(a), which states that “High pressure is considered tobe pressure in excess of that allowed by the ASME B16.5 PN 420(Class 2500) rating for the specified design temperature and mater-ial group.” This is not a requirement, and the base Code may besatisfactorily used at pressures higher than ASME B16.5 PN 420(Class 2500). However, the base Code rules become increasinglyconservative and, in fact, impossible to use as the pressureapproaches the allowable stress (including quality factors).

The rules provide a combination of considerations. Whilereduced wall thicknesses and provisions that are specific to theneeds of high pressure (e.g., not including thread depth as anallowance under specific conditions), additional material toughness,analysis during design, inspection, and testing are required. A back-ground paper on these rules by Sims [13] is listed in the references.

There are no provisions for Category M Fluid Service.The criteria consider limit load failure and fatigue. Elevated

temperature creep effects are not included; thus, the use ofChapter IX is limited to temperatures below the creep regime forthe materials of construction.

See the ASME B31.3 Code for specific requirements. SectionVIII, Division 3, Pressure Vessels, Alternative Rules for Con -struction of High Pressure Vessels, was completed after ChapterIX. As a result, there are various references to the requirements ofSection VIII, Division 2 that have been changed to either includeDivision 3 as an acceptable alternative or to simply require theDivision 3 rules rather than the Division 2 rules. The Division 3rules are generally more applicable, as they were developed forhigh-pressure equipment. Reference 13 provides more insight onthe development of rules in this chapter.

36A10.2 Organization of Chapter IXChapter IX follows the same paragraph numbering as the base

Code, Chapters I through VI; however, the paragraphs start withK for high-pressure piping in accordance with Chapter IX. Todetermine the rules for high-pressure piping systems, simply referto Chapter IX. If rules elsewhere in the Code apply, they are refer-enced in Chapter IX.

36A10.3 Pressure Design of High-Pressure PipingBeyond a certain pressure, it is not possible to design piping in

accordance with the basic wall thickness equation, equation 3, in

the base Code. Assuming Y is equal to zero (note that Yapproaches zero as the inside diameter approaches zero; see defin-ition of Y in para. 304.1.1), the required wall thickness is equal tothe outside radius of the pipe when the pressure is equal to theallowable stress times the quality factor. However, heavy wallpipe has substantial pressure capacity beyond the point where thecircumferential stress at the bore reaches yield. For high internalpressure, the radial stresses due to the surface traction of internalpressure significantly affect yielding of the material on the insideof the pipe, considering the Von Mises or Tresca yield theory.

Equation 34 in Chapter IX provides the required thickness forhigh-pressure straight pipe. Rather than being based on maximumcircumferential stress, as in the base Code, it is based on limitload pressure. The following equations for calculation of requiredwall thickness are provided. Equations 35a and 35b in the Codeprovide the allowable pressure based on available thickness.

These equations provide a margin of 1.732 (which is ) relativeto through-thickness yielding, based on von Mises theory, andelastic-perfectly plastic material behavior when the allowablestress is based on two-thirds yield. When the allowable stress isbased on 90% of the yield strength, the factor is reduced to as lowas 1.5 at elevated temperatures.

There is not a quality factor included since the minimum per-mitted quality factor in Chapter IX is 1.0.

When the mechanical allowances are not specified to be internalor external, they are assumed to be internal. The external thread onpipe can be neglected in the mechanical allowances when a numberof criteria are met. This recognizes that the threaded fitting, typi-cally a threaded flange, to which the pipe is attached can effectivelyreinforce the pipe for internal pressure under certain conditions.

The allowable stress in Chapter IX is based on yield strength andnot tensile strength, as a result, there will be a greater advantagewith respect to wall thickness to use Chapter IX for steels with highyield to tensile strength ratios. This is because the base Code allow-able stress would be controlled by one-third the tensile strength.

Similar to but more limited than the base Code, provisions fordesign of specific types of components are provided, and listedcomponents are accepted. The table of listed components is TableK326.1.

36A10.4 External PressureBuckling due to external pressure is not generally a concern

for high-pressure piping. However, the limit pressure deter-mined using equations 34 and 35 is not always conservative forexternal pressure on straight pipe, considering buckling and,under rare circumstances, when external pressure does not causeaxial compression of the pipe. In the latter case, collapse can bepredicted by triaxial stress states and yield theory. When D/t <3.33 and at least one end of the pipe is exposed to full externalpressure, which produces compressive axial stress, equations 34and 35 for internal pressure can be used. In all other circum-stances, the base Code rules for external pressure design ofstraight pipe are used.

36A10.5 Design for Sustained and Occasional LoadsThe criteria for sustained loads is the same as the base Code.

The longitudinal stress due to pressure, weight, and other sus-tained loads must be less than Sh. The criteria for occasionalloads is more conservative than the base Code. A factor of 1.2times the allowable stress is used (the same as Section VIII,Division 1) rather than a factor of 1.33.


PROPRIETARY A

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36A10.6 Design for Thermal Expansion and FatigueFlexibility analysis is conducted similar to the base Code.

However, only the more conservative equation for SA, whichassumes that SL � Sh, is used (equation 32). The allowablestresses from Appendix K are used rather than the allowablestresses from Appendix A. These will be higher when tensilestrength controls the allowable stresses in Appendix A.

Chapter IX (para. 304.8) requires a detailed fatigue analysis inaddition to the flexibility analysis provided in the base Code. Forthis analysis, the allowable stress amplitude from the fatiguecurves in Section VIII, Division 2, Part 3 para. 3.15 and Annex3.F are used or the fatigue analysis is based on ASME BPVC,Section VIII, Div 3.

The fatigue analysis should include the typically high strainsdue to internal pressure, in particular those at the bore of thepipe, as well as the stress due to thermal expansion. Since thecalculated stress is compared to the polished bar fatigue curve,rather than a butt-welded pipe fatigue curve, the stresses calcu-lated in accordance with the flexibility analysis rules of ASMEB31.3 in most cases need to be multiplied by a factor of two. Allcomponents with stress intensification factors greater than oneand pipe at girth welds should have the stresses multiplied bytwo.

The requirements for fatigue analysis pose some challengingproblems to the designer. Some of these are highlighted below.

(1) The designer must consider both pressure and displacementcycles. Thus, a load histogram and a procedure such asrainflow counting is appropriate to determine the variety ofstress ranges and numbers of cycles at each stress range thatthe piping must be designed for. For example, there may benormal pressure cycles, which may be more numerous thanthermal displacement cycles, and also pressure pulsations.There will be some number of cycles at a maximum stressrange, which could be the normal pressure plus pulsationplus displacement stress, plus many cycles with smallerstress ranges to consider.

(2) Fatigue analysis per Section VIII, Division 2 deals withstresses at a point, whereas the flexibility analysis rules ofASME B31.3 do not inform the designer as to the locationand direction of stresses that are calculated. For example,the stresses in an elbow due to in-plane bending are throughwall bending and greatest in the circumferential direction,and should be directly added to the pressure stress; whereasthe stresses due to bending in straight pipe are gross bend-ing on the pipe section and longitudinal, and should becombined with the pressure stress to determine Trescastress intensity.

(3) The stresses due to internal pressure vary through thethickness; this should be considered in determining whatpressure stress to combine with the deflection stresses(e.g., bore stress should be considered for an elbow andthe outside stress should be considered for a threadedjoint).

(4) The radial stress through the wall of the pipe [compressiveand equal to internal pressure on the inside surface and gen-erally considered to be zero on the outside surface (for apipe under internal pressure)] can be a significant compo-nent of the Tresca stress intensity. All these mean that adesigner tackling a fatigue analysis for Chapter IX pipingshould be an expert, intimately familiar with the stress dis-tributions in thick-wall piping components.

ASME B31.3 provides the equation (37) for the stress intensityon the inside surface of straight pipe due to internal pressure.Note that this is not likely to be the controlling location in the sys-tem. As such, its usefulness is limited.

36A10.7 MaterialsThe allowable stress is provided in Appendix K, Table K-1. It

is two-thirds of the material yield strength, to be consistent withthe pressure design equation. For solution-heat-treated austeniticstainless steels and certain nickel alloys with similar stress-strain behavior, the minimum of two-thirds the specified mini-mum yield strength and 90% of the yield strength at temperatureis used. Similar to the base Code, this is because the materialhas significant strength beyond the nominal 0.2% offset yieldstress.

The same as the base Code, these higher stress values providedfor stainless steel and similar material are not recommended forflanges and similar components where slight deformation cancause leakage or other malfunction.

The impact test requirements are a very important part of thematerial requirements in Chapter IX for high-pressure piping.Essentially all high-pressure piping materials and welds must beimpact tested to determine that they have sufficient notch tough-ness for any temperature condition at which stresses exceed 41MPa (6 ksi). Impact test requirements are provided in para.K323.3.

For materials, at least one set per lot is required. For impacttests on welds, significantly more testing is required than the baseCode. Whereas the base Code only requires impact testing as partof the weld procedure qualification, Chapter IX requires impacttesting for each welder, welding procedure, type of electrode, orfiller metal, and each flux to be used. For tests on welds, separatetests are not required for each lot of material. Test specimens forthe welds and heat-affected zones are required.

The minimum permissible temperature for a material is theminimum temperature at which an impact test that satisfies theCode requirements was performed. The only exception to this isthe 41 MPa (6 ksi) exemption, but that exemption may only beused down to −460C (−500F). Impact testing, regardless of stress,is required for use at temperatures below that temperature.

36A10.8 FabricationRequirements for qualification of welding procedures and

welders or welding operators follow Section IX. However, thereare additional requirements and limitations.

General fabrication requirements pertaining to end preparation,alignment, welding, preheat, and postweld heat treatment are pro-vided. They are largely similar to the base Code with some varia-tions. For example, the recommended preheat temperature, perTable 330.1.1, in the base Code is required for Chapter IX.

36A10.9 ExaminationIn general, Chapter IX requires 100% examination. This

includes 100% visual examination of materials and components;fabrication; threaded, bolted, and other joints; piping erection;and pressure-containing threads. All girth, longitudinal, andbranch connection welds are required to be 100% examined byradiography. Ultrasonic and inprocess examination are not accept-able alternatives. The acceptance criteria for welds are providedin Table K341.3.2.

36-18 • Chapter 36

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36A10.10 TestingAll elements, including all components and welds, of a high

pressure piping system, except for bolting and gaskets used dur-ing final system assembly, are required to be subjected to a fullpressure test. This pressure test need not be performed on theinstalled piping system, but can be done on piping subassembliesprior to erection. The full pressure test is the base Code hydrotestpressure (1.5) times the design pressure times the temperaturecorrection factor, except that there is no limitation on the tempera-ture correction factor. Furthermore, if this test is performed as apneumatic test, the same full pressure, as for a hydrotest, isrequired. Some minor exceptions are permitted based on limitingcomponents.

36A10.11 RecordsChapter IX contains more substantive requirements for record

transfer to the owner and the retention of records than the baseCode. For example, the base Code does not contain requirementsrelative to documentation of the engineering design. However,Chapter IX requires records of the following to be provided to theowner or the (owner’s) Inspector:

(1) the engineering design;(2) material certifications

36A11 CHAPTER X, HIGH PURITY PIPING

This is a new part of the B31.3 Code termed as Chapter X,“High Purity Piping” developed as the result of a lot of hard workby ASME volunteers over the past few years. This chapter hasbeen closely coordinated with another new ASME standard onBioprocessing Equipment (BPE). The need for specific changes tothe code was required to address maintaining hygienic designpractices for the bioprocessing, semiconductor, pharmaceuticalsmanufacturing, biofuels, and food production.

Chapter X is organized like the rest of the base code, and onlyaddresses requirements which are different than those in the basecode. The owner is responsible for designating a fluid service as“High Purity Fluid Service” and to allow the alternative rules ofthis chapter to be applied.

Specific differences in Chapter X include the following:

High Purity Fluid Service valves,Flanged Joints are not recommended,Expanded Joints in accordance with para. 308.2.2 are notpermitted,Expanded joints, flared tube fittings and caulked jointsdescribed in paras. 313, 315 and 316 are not permitted,Threaded joints are not recommended,Face seal or hygienic clamp-type fittings are discussed andrecommended,Brazing and Soldering are not permitted.

Orbital welding and Weld Coupon Examination are addressed.This may be one of the most significant changes which weremade to the base code for High Purity Service. The requirementsfor orbital welding and verification of the quality of the weldwithout compromising the cleanliness of the system is discussedat length under Part 10 Inspection, Examination and Testing.

Finally, alternative leak tests are permitted as an alternate topneumatic leak testing. Pneumatic leak testing is identified as the

preferable method, however with the owner’s approval, a heliummass spectrometer test may be used.

Part 11 of Chapter X provides for additional considerationswhen both High Purity and Category M fluid service are applica-ble. The user is cautioned these requirements would apply to botha highly hazardous fluid service and also where very high purityrequirements apply. While the code attempts to provide guidanceand rules, the Code is not a design handbook and one should notrely strictly on Code rules in these types of fluid services.

36A12 APPENDICES IN THE CODE

A number of appendices are included in the Code as listedbelow with a brief description of each and if they are mandatoryor if they are provided for additional guidance.

Appendix A Allowable Stresses and Quality Factors forMetallic Piping Bolting Materials

Table A-1 Basic Allowable Stress in Tension for Metals Theallowable stress tables provide allowable stresses for materialswhich are “listed” in the Code, these are currently in USCustomary Units, however they are being converted to Metric andas the conversion is made, Metric versions are posted on theASME web site for information only. These should become therequired tables sometime in the future. The appendix is organizedby material type and within those types are component types likePipe and Tubes, Forgings and Fittings, and Plates and Sheets,Castings, etc.

Along with allowable stress at temperature, these tables providea lot of other important information including “P numbers for Welding, Minimum Temperatures, warning notes, SpecifiedMinimum Yield and Tensile Strengths. The important part of usingthese tables is making sure the user is familiar with all of the infor-mation provided and the notes associated with the material.

Table A-1A Basic Casting Quality Factors Ec Table A-1Aprovides quality factors and references associated with listed cast-ing specifications to be applied to the basic allowable stresses forthe casting materials.

Table A-1B Basic Quality Factors for Longitudinal WeldJoints Both Table A-1B and Table 302.3.4 provide a factor to applyto the basic allowable stress which is used in the calculation ofwall thickness or the circumferential stress.

Table A-2 Design Stress Values for Bolting MaterialsSimilar to Table A-1 for Bolting Material.

Appendix B Stress Tables and AllowablePressure Tables for NonmetalsRequirements

This table is similar to Table A-1 except it applies to Non-metalscovered in Chapter VII. The user is cautioned the Non-metallicindustry is not as standardized as steel and other metal products,as a result the compliance with supplier requirements and recom-mendations is important with most nonmetallic piping materialsand components.


PROPRIETARY A

SME

Appendix C Physical Properties of Piping MaterialsRequirements

As noted in the title, this appendix provides physical propertiesrequired for the analysis of piping systems. This information isprovided for convenience and if the user has better data, it can andshould be used.

Appendix D Flexibility and Stress IntensificationFactors Requirements

As discussed in 36A3.5.3 and several references, most of thestress intensification factors provided in this appendix were devel-oped from fatigue testing which was completed more than 50years ago. Recent research on these factors will hopefully beavailable in ASME B31J in the future. Until then, if the user hasbetter information on Flexibility or Stress Intensification Factorsthey should be used.

Appendix E Reference Standards RequirementsAny listed standards or references in the Code are to a generic

standard without the edition or date. The most recently approvededition is noted in this appendix. This is a very difficult task andthis appendix is frequently out of date in the ASME B31.3 Codeand other ASME Codes. ASME is currently working on this issueand hopes to improve how approved editions are reviewed andupdated in the future.

Appendix F Precautionary Considerations Guidance This is a very important appendix for the user to become famil-

iar with. While it does not contain any requirements, it does provide warnings for situations which might otherwise be over-looked. It kind of goes along with the introduction statement “theCode is not a design handbook.”

Appendix G Safeguarding Guidance Guidance provided here would generally apply to Chapter VIII

Category M fluid service, however they could be applied to anyhazard.

Appendix H Sample Calculations for BranchReinforcement Guidance

As was noted in 36A3.3.2.5, the branch reinforcement rulesand figures can be confusing, therefore this appendix was pro-vided just to give the user some examples of how to apply therules. This appendix will also be provided in SI units in the 2012edition of the Code.

Appendix J Nomenclature InformationA useful list of the Symbols used in the code along with defini-

tion and reference to paragraphs where they are used.

Appendix K Allowable Stresses for High PressurePiping Requirements

Similar to Appendix A, however requirements are applicableonly when use of Chapter IX is specified.

Appendix L Aluminum Alloy Pipe FlangesSpecification

Contains pressure-temperature ratings, materials, dimensions,and markings of forged aluminum alloy flanges.

Appendix M Guide to Classifying Fluid ServicesGuidance

A Simple flow chart to help the Owner make the decision toclassify a fluid service.

Appendix P Alternative Rules for Evaluating StressRange Requirements

The alternate method in this appendix was discussed in36A3.2.1, Code requirements for Sustained and Self LimitingLoads. As was noted then, this Appendix is the only place wherethese two load cases are combined. These are alternative require-ments to the self limiting or thermal loads, however base coderequirements for sustained loads must still be met.

Appendix Q Quality System Program Guidance This appendix provides an option for the owner to specify a

quality system program. When specified by the owner, it wouldbecome mandatory.

Appendix S Piping System Stress Analysis ExamplesGuidance

This appendix is trying to provide generic examples of pipinganalysis for both sustained and self limiting loads. The exampleshave proved difficult to develop with the consensus of the SectionCommittee Members, so this appendix will continue to growslowly.

Appendix V Allowable Variations in ElevatedTemperature Service Guidance

Guidance on systems which operate in the creep range andemphasis on temperature excursions on the design life of pipingsystems in this range.

Appendix X Metallic Bellows Expansion JointsRequirements

Rules associated with Expansion Joint Design, and Design con-siderations when expansion joints are included in the design.

Appendix Z Preparation of Technical InquiriesRequirements

ASME procedures have specific administrative requirementsassociated with how inquires can be submitted to the Code, andwhat types of questions will and will not be answered by theSection Committee. This Appendix provides the user some infor-mation on how to submit an inquiry or request to the committeefor Code revisions.

PART B: ASME CODE B31.5REFRIGERATION PIPING ANDHEAT TRANSFER COMPONENTS

36B.1 INTRODUCTION

This section is based on the 2010 edition of ASME B31.5, andwill provide frequent reference to other chapters covering B31Codes in this book that provide background information, not spe-cific to this Code.

The first thing to note is B31.5 paragraphs are numbered in the500 series. This coincides with the previous two codes/chapterswhere B31.1 was numbered with 100 series, and B31.3 was num-bered with the 300 series.

36-20 • Chapter 36

PROPRIETARY A

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36B.2 SCOPE

This code is specific to refrigeration piping and heat transfercomponents. By limiting the scope, it allows the user to concen-trate on the refrigeration system and not have to become familiarwith the more general codes previously discussed. The scope islimited to −320�F, so any piping colder than this should bedesigned, fabricated and constructed with materials within thescope of B31.3 piping.

36B.3 REFRIGERANT SAFETYCLASSIFICATION

This is the first significant difference between the previouscodes. Table 500.2-1, provides a list of safety classifications forrefrigerants and refrigerant Blends (Table 500.2-2) with a specificrefrigerant number, Chemical Name, Chemical Formula andSafety Group if it has been assigned.

Refrigerant and refrigerant mixtures: the fluid used for heattransfer in a refrigerating system that absorbs heat during evapo-ration at low temperature and pressure, and releases heat duringcondensation at a higher temperature and pressure. The safetyclassification group consists of two characters (e.g., A1 or B2).The capital letter indicates the toxicity and the Arabic numeralindicates the flammability, based on the criteria in Tables 500.2-1and 500.2-2.

These numbers and classifications are for use in the design ofthe refrigeration system; subsequent requirements in the coderefer to the toxicity or flammability of the refrigerants for addi-tional considerations.

36B.4 DESIGN CONDITIONS ANDCRITERIA

Part 1 covers the design criteria and includes the allowablestresses for materials. The previously covered code sectionsincluded this information in the stress tables as part of anAppendix A. While the materials are similar, the number of mate-rials included is much more limited, and the temperature range islimited to 400 degrees F. This is a reflection of the limited scopeof this book section as well as a limitation of some of the materi-als which are permitted.

36B.4.1 Pressure DesignPart 2, Pressure Design is covered in the 504 series of para-

graphs with the same basic criteria as B31.1 (series 104) andB31.3 (series 304). The basis and formulas are almost identical,so no further explanation is provided on pressure design.

36B.4.2 Piping Component and JointsParts 3 and 4 (Paragraphs 505 through 518) cover specific

requirements and limitations for piping, piping components andjoints. These requirements are based on size, temperature andsafety classification of refrigerants and should be reviewed care-fully when developing a piping specification for a particularrefrigerant system.

36B.4.3 Expansion Flexibility and SupportsPart 5 (Paragraphs 519 through 521) is a condensed version of

the Part 5 in B31.1 and B31.3. See Chapter 35 on power piping

for a detailed discussion on the basis of these requirements. B31.5includes a lot of information which is provided in various appen-dices in both B31.1 and B31.3 in the book section itself, so toactually use, or follow the requirements might be a little easier.

36B.4.4 MaterialsChapter III covers acceptable materials, material requirements

such as impact testing and how to qualify unlisted materials foruse in B31.5 applications. Again, the chapter is very similar to therequirements in the previous chapter on B31.3. In a few cases, therequirements might be slightly different or more straight forwardbecause of the more limited scope. Also note B31T which is cov-ered later in this chapter will cover similar requirements for mate-rial toughness.

36B.4.5 Dimensional RequirementsChapter IV on dimensional requirements provides a list of ref-

erence standards which are approved by the standard. It also pro-vides requirements for components which are not listed. Table526.1 which lists the approved dimensional requirements is simi-lar to Table 126.1 in B31.1 and Table 326.1 in B31.3. Again, thelimited reference standard reflects the narrower scope of this codesection.

36B.4.6 Fabrication and AssemblyChapter V on fabrication and assembly is again very similar to

the Chapters in B31.1 and B31.3. They are not identical howeverand the user is cautioned to follow the appropriate design codecarefully. Notable differences are a number of typical details onthe use of backing rings so that considerable attention to accept-able and unacceptable weld details for plate closures are required.

36B.4.7 Examination, Inspection, and TestingChapter VI on Examination, inspection and testing is the final

chapter and is also similar to the B31.1 and B31.3 chapters relat-ing to these topics. While format and type of requirements are thesame, the specific code must be followed and the user is cautionedthe requirements do change between sections and editions.

PART C: ASME CODE B31.9 BUILDING SERVICES PIPING

36C.1 INTRODUCTION

This section is based on the 2008 edition of B31.9 Code. Theorganization of the code is the same as the preceding 3 Codebooks (Part A, B and C), so only the differences are going to behighlighted as part of this discussion. Similar to B31.5, the scopeof Building Services piping is limited. The intent is to providesimplified rules for piping which would typically be found inindustrial, institutional, commercial, and public buildings, andmulti-unit residences.

36C.2 SCOPE

The services are limited by the requirements in 900.1.2 to whatwould be typical utilities such as water, antifreeze solutions forheating and cooling, steam, condensate, vacuum systems, com-pressed air or other nontoxic, nonflammable gases, and com-bustible liquids including fuel oil.


PROPRIETARY A

SME

Boiler external piping similar to the piping discussed inChapter 35 on B31.1 is included, but only as limited by the fol-lowing pressures and temperatures:

Steam Boilers 15 psig max.Water Heating Units 160 psig max. and 250�F max.

Other Material and Size limits are as follows:

Carbon Steel: NPS 48 and .5” wallStainless Steel: NPS 24 and .5” wallAluminum NPS 12Brass and Copper NPS 12 (12.125” OD for Copper Tubing)Thermoplastics: NPS 24Ductile Iron NPS 48Reinforced Thermosetting Resin NPS 24

This list does not prohibit other materials which may be used asnoted in Chapter III.

Pressure limits, piping systems designed to ASME B31.9 arelimited to pressures as noted below:

Steam and Condensate not in excess of 150 psigLiquids not exceeding 350 psigVacuum is limited to 1 atmosphere external pressureCompressed air and gas not in excess of 150 psig

Temperature limits, piping systems designed to ASME B31.9are limited to at or below the temperature noted below:

Steam and Condensate: 366�FOther gases and vapors: 200�FOther nonflammable liquids: 250�F

The minimum temperature for all services is 0�FAny piping outside of the above limits should be designed to

another section of the B31 series of pressure piping codes such asB31.1, B31.3, B31.5, etc. as determined by the owner. See intro-duction to any of the piping code sections for additional guidance.

36C.2.1 DesignThe design requirements in Chapter II are similar to the other

pressure piping codes discussed previously. One notable differ-ence is paragraph 921.1.3 where deflection of piping under dead-weight is limited. The calculated stresses associated with thepiping span also have a specific limit as opposed to the other pip-ing codes which limit just the longitudinal stress associated withsustained loadings. Span charts are also provided for a number oftypical piping materials in figures 921.1.3-1 and 921.1.3-2.

Another noticeable difference is 921.2.1 Fixtures where specificrequirements are provide for guides and anchors associated withexpansion joints. While the other previous codes require these to beconsidered, this paragraph provides specific formulas for buckling.

36C.2.2 MaterialsSimilar to other sections of the pressure piping codes previously

discussed, specific materials and limitations are noted in Chapter IIIand should be reviewed prior to any design work under this Code.

36C.2.3 Component Requirements and StandardPractices

Listed standards which are acceptable to B31.9 piping systemsare identified in Chapter IV. While design to alternate nonstan-dard components are permitted by para 904, adherence to thelisted standards is recommended.

36C.2.4 Fabrication, Assembly, and ErectionChapter V is similar to the other Pressure Piping Code Sections

with one or two notable exceptions. The wall thicknesses and material limits in the scope are such

that Post Weld Heat Treatment is not required for any of the pip-ing which is permitted under B31.9 unless specified in the engi-neering design.

Para. 930.2 permits Mechanically Formed Extruded Outlets inCopper Tube. This paragraph provides a formula for calculatingthe allowable pressure for these outlets.

36C.2.5 Inspection, Examination, and TestingChapter VI provides similar requirements to the other Pressure

Piping Codes for verification of the piping systems to meet therequirements of the code that will pass appropriate leak tests.

PART D: ASME STANDARD B31E: SEISMIC DESIGN AND RETROFITOF ABOVE-GROUND PIPINGSYSTEMS

36D.1 INTRODUCTION

This is a new standard which was issued for the first time withthe 2008 edition. This standard is very different than the otherbook sections which have been discussed so far. B31E is not asso-ciated with specific piping system, instead it is intended to pro-vide more explicit and structured guidance for seismic design ofnew or existing piping systems. Currently most of the B31Pressure Piping Book Sections require some sort of considerationof seismic design for piping systems; however they give little orno guidance on how this should be accomplished. Likewise build-ing codes and ASCE 7 provide requirements for the seismicdesign of structures, but do not have rules which address the pres-sure design of piping systems during the seismic event.

B31E is the first attempt to put specific rules together whichcan be applied to new or existing piping systems to insure theywill function as intended during a seismic event. There are stillsome issues being worked out between the requirements of thepiping code and the structural design codes to make sure they areworking together well. The user is cautioned to watch for the lat-est changes to both ASME B31E and ASCE 7.

36D.2 SCOPE

The rules and basis for the seismic design are in a large partbased on the performance of existing piping systems built to oneof the B31 Pressure Piping Code Sections which were studiedafter past seismic events. As a result, the requirements in thisstandard are only valid when the piping system complies with thematerials, design, fabrication, examination, testing, and inspectionrequirements of the applicable ASME B31 Code section.

Para. 1.3 identifies a number of required inputs which arerequired before a piping system can be evaluated in accordancewith this standard. These inputs provide the required informationto correctly classify the importance of a piping system and haz-ards involved, function required of the piping system during andafter the seismic event, free-field seismic input, in-structure seis-mic response spectra and a number of other responsibilities asso-ciated with issues which could affect the seismic performance of

36-22 • Chapter 36

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the piping system or attached active components. It is very impor-tant to understand and assign these responsibilities prior to evalu-ating the potential performance of a piping system during a seismicevent.

36D.3 MATERIAL

This is a very short section which reinforces the materials mustbe to one of the applicable ASME B31 Code sections, includingevaluation of the condition of existing systems and supports to besure they still meet the intent of the original construction code.

36D.4 DESIGN

36D.4.1 Seismic LoadingSeismic Loading discussed in Para. 3.1 are described with ref-

erence to standards such as ASCE 7. As noted earlier, the coor-dination with this standard is an ongoing activity and care mustbe taken to verify the requirements of a specific B31E editionare consistent with the requirements and associated factors pro-vided by specific edition of ASCE 7 or other structural designstandard.

36D.4.2 Design MethodASME B31E provides two different methods for the evaluation

of piping systems based on the classification of the system, mag-nitude of the seismic input, and pipe size.

36D.4.3 Design by RuleDesign by Rule is a very simple approach which provides for

lateral supporting of the piping based on span charts, or formulas.

This approach was commonly referred to as spacing criteria in theseismic design of small bore nuclear piping. See ASME B31E,Para. 3.3 for the specific piping systems where this approach isacceptable as well as the span requirements between lateral sup-ports. Table 1 from ASME B31E (Figure 36D.4.3-1) and Table 2(Figure 36D.4.3-2) are shown below.

36D.4.4 Design by AnalysisDesign by analysis is covered in ASME B31E, Para. 3.4. The

analysis requirements are similar to the analysis which would bedone on any piping system to verify the sustained and self-limitingstresses are within the applicable B31 code allowable stress limits,however the piping is exposed to loadings from the seismic event.These loadings may be calculated by static or dynamic analysis.Allowable stress limits are provided, however the user is cautionedchanges to the loading criteria from the structural standards arestill being resolved with ASME B31E to produce results which areconsistent with the past research.

36D.4.5 Other ConsiderationsThe remainder of the document contains a number of very

important items which must be considered as part of a seismicdesign including mechanical joints, seismic restraints, equipmentand components, and seismic interactions.

36D.4.6 ReferencesA number of important references are provided in ASME

B31E, the user may also find some of the following referencesuseful which document the performance of piping systems whichhave been exposed to real as well as simulated seismic events onshaker tables.

References 25 to 31 pertinent to this Code and Seismic Designin general are listed at the end of this chapter.


TABLE 36D.4.3-1 SEISMIC DESIGN REQUIREMENTS, APPLICABLE SECTIONS(Source: Table 1 of ASME B31E, 2008)

PROPRIETARY A

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PART E: ASME STANDARD B31J: STANDARD TEST METHOD FORDETERMINING STRESSINTENSIFICATION FACTORS (I-FACTORS) FOR METALLICPIPING COMPONENTS

36E.1 INTRODUCTION

This standard was originally developed to provide an experi-mental method to determine SIF’s for components or joints whichhave not been provided in the ASME B31 Pressure Piping Codesections. It is currently being revised to increase this scope toinclude updated SIFs and flexibility factors for common compo-nents and branch to header connections of various sizes. Thischange in scope is the first step in incorporating recent researchsponsored by ASME. Once this is complete, B31 Pressure PipingBook Sections can reference B31E for SIF’s.

36E.2 TEST PROCEDURE

The test equipment shown in Fig. 3.1 of B31J is similar to thetest equipment described at length in references 8 & 14.

Non-mandatory Appendix A in B31J is a commentary on thisdocument, so no further commentary is provided in this chapter.

PART F: ASME STANDARD B31T: STANDARD TOUGHNESSREQUIREMENTS FOR PIPING

36F.1 INTRODUCTION

B31T was published for the first time in 2010 and this commen-tary is based on this edition. Each of the previously discussed B31Pressure Piping Code Sections had material requirements associ-ated with low temperature and the possibility for brittle failure.The requirements were similar, but not identical and sometimesvery difficult to follow. This standard was developed to try to makethese requirements easier to understand and improve the consis-tency of the requirements. In the future, the B31 Pressure PipingCode sections may invoke this document in whole, or in part and

in that case, the requirements in this document would becomemandatory.

36F.2 MATERIALS

Materials are grouped by a “T-Number,” which are shown inTable 3.2-1. The minimum temperatures permitted and associatedimpact test requirements are shown in Table 3.1.1 based on thisgroup number which is shown in Column 1. Table 3.1.1 is providedin both SI and US Customary Units. An example of part of thistable is shown below in Figure 36F.2-1

Column 2 lists the thickness of materials where requirementsvary by thickness.

Column 3 lists any notes which may be applicable to this materialgroup or the maximum possible size of the impact test specimen.

Column 4 is the lowest temperature at which the material canbe used without addition testing or stress limits, so if the designminimum temperature is above this number, no other low temper-ature requirements apply.

Columns 5 & 6 list minimum temperatures for the materialwith and without impact tests. Where the material thickness doesnot permit impact testing,

Column 7, 8 & 9 are applicable to any welds which must bequalified for the low temperature. The stress ratios above andbelow .3 are listed separately because low stressed materials areless prone to brittle failure.

Columns 10–17 provide additional temperature limits based onstress ratios from 1 to .3 where a lot of carbon steel materials aregiven some addition relief if they are not highly stressed.

Column 18 provides the minimum temperature where the mate-rial can be used if the Stress Ratio is less than .3. This stress ratiois the same as keeping the stress in the material at less than 10%of the tensile strength.

36F.3 FABRICATION

Section 3.7 covers fabrication and requirements associated withthe low temperature limits and weld qualification and impact test-ing requirements similar to all of the B31 Pressure Piping Codeswhich had been discussed as part of the material and weld proce-dure qualifications in the previous section. This section also

36-24 • Chapter 36

TABLE 36D.4.3-2 MAXIMUM SPAN, FT (M), BETWEEN LATERAL SEISMIC RESTRAINTS FOR STEEL PIPE WITH A YIELDSTRESS OF 35 KSI (238 MPA), IN WATER SERVICE AT 70˚F (21˚C) (Source: Table 2 of ASME B31E, 2008)

PROPRIETARY A

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TABLE 36F.2-1 LOW-TEMPERATURE SERVICE REQUIREMENTS BY MATERIAL GROUP(Source: First page of Table 3.1-1 of ASME B31T, 2010 )

PROPRIETARY A

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includes some additional and restrictions associated with formingoperations which could also affect the impact properties of thematerial and how they should be qualified.

36F.4 TESTING

Section 4 provides requirements for impact testing when it isrequired based on Table 3.1.1 and the design minimum tempera-ture and associated stress level.

36F.5 APPENDICES

A number of tables are available in Mandatory Appendiceswhich provide temperature/thickness curves, stress ratio curves,and listing of material specifications by “T-numbers”.

Finally, Non-mandatory Appendix A provides a flow chart forusing the document, and Appendix B provides guidelines forestablishing T-number groups for materials which were not cov-ered by this document.

36.2 REFERENCES

1. Boardman, H. C., “Formulas for the Design of Cylindrical andSpherical Shells to Withstand Uniform Internal Pressure,” The WaterTower, vol. 30, 1943.

2. Bergman, E. O., “The New-Type Code Chart for the Design ofVessels Under External Pressure,” Pressure Vessel and PipingDesign, Collected Papers 1927–1959, The American Society ofMechanical Engineers, 1960, pp. 647–654.

3. Holt, M., “A Procedure for Determining the Allowable Out-of-Roundness for Vessels Under External Pressure,” Pressure Vessel andPiping Design, Collected Papers 1927–1959, The American Societyof Mechanical Engineers, 1960, pp. 655–660.

4. Saunders, H. E., and Windenburg, D., “Strength of Thin CylindricalShells Under External Pressure,” Pressure Vessel and Piping Design,Collected Papers 1927–1959, The American Society of MechanicalEngineers, 1960, pp. 600–611.

5. Windenburg, D., and Trilling, C., “Collapse by Instability of ThinCylindrical Shells Under External Pressure,” Pressure Vessel andPiping Design, Collected Papers 1927–1959, The American Societyof Mechanical Engineers, 1960, pp. 612–624.

6. Windenburg, D., “Vessels Under External Pressure: Theoretical andEmpirical Equations Represented in Rules for the Construction ofUnfired Pressure Vessels Subjected to External Pressure,” PressureVessel and Piping Design, Collected Papers 1927–1959, TheAmerican Society of Mechanical Engineers, 1960, pp. 625–632.

7. Biersteker, M., Dietemann, C., Sareshwala, S., and Haupt, R. W.,“Qualification of Nonstandard Piping Product Form for ASME Codefor Pressure Piping, B31 Applications,” Codes and Standards andApplications for Design and Analysis of Pressure Vessels and PipingComponents, PVP vol. 210–1, The American Society of MechanicalEngineers, 1991.

8. Markl, A., “Fatigue Tests of Piping Components,” Pressure Vesseland Piping Design, Collected Papers, 1927–1959, The AmericanSociety of Mechanical Engineers, pp. 402–418, 1960.

9. Robinson, E. “Steam-Piping Design to Minimize CreepConcentrations,” Pressure Vessel and Piping Design, CollectedPapers, 1927–1959, pp. 451–466, 1960.

10. Becht IV, C., “Elastic Follow-up Evaluation of a Piping System witha Hot Wall Slide Valve,” Design and Analysis of Piping, PressureVessels, and Components-1988, PVP-Vol. 139, The AmericanSociety of Mechanical Engineers, 1988.

11. Bednar, H., Pressure Vessel Design Handbook, Van NostrandReinhold Co., New York, 1986.

12. Becht, C., Chen, Y. and Benteftifa, C., “Effect of Pipe Insertion onSlip-On Flange Performance,” Design and Analysis of PressureVessels, Piping, and Components-1992, PVP-Vol. 235, The AmericanSociety of Mechanical Engineers, 1992.

13. Sims, J., “Development of Design Criteria for a High Pressure PipingCode,” High Pressure Technology—Design, Analysis, and Safety ofHigh Pressure Equipment, PVP-Vol 110, Ed. D. P. Kendall, TheAmerican Society of Mechanical Engineers, 1986.

14. Piping Engineering, Sixth Edition, 1986, Tube Turns, Inc.

15. Piping Design & Engineering, Seventh Edition, 1995 GrinnellCorporation.

16. STP-PT-028, Impact Test Exemptions.

17. Harvey, John F., Theory and design of modern pressure vessels, VanNostrand Reinhold Co., New York. 1974.

18. Short II, W. E., “Overview of Chapter VII, Nonmetallic Piping andPiping Lined with Nonmetals in the ASME B31.3 Chemical Plant &Petroleum Refinery Piping Code,” Codes and Standards andApplications for Design and Analysis of Pressure Vessel and PipingComponents-1989, ASME PVP-Vol. 161, American Society ofMechanical Engineers, 1989.

19. Short II, W. E., “Coverage of Non-Metals in the ASME B31.3Chemical Plant and Petroleum Refinery Piping Code,” Journal ofProcess Mechanical Engineers, IMechE Vol. 206, pp. 67–72,Institute of Mechanical Engineers, May 1992.

20. WRC 415, Literature Survey and Interpretive Study onThermoplastic and Reinforced-Thermosetting-Resin Piping andComponent Standards, W. E. Short II, G. F. Leon, G. E. O. Widera,and C. G. Zui, The Welding Research Council, September, 1996.

21. Nayyar, Mohinder L., Piping Handbook, Mcgraw-Hill SeventhEdition.

22. ASME PCC-1, Guidelines for Pressure Boundary Bolted FlangeJoint Assembly, The American Society of Mechanical Engineers,2010.

23. Pipe Fabrication Institute, PFI ES-48 Random Radiography, 2008.

24. The Copper Tube Handbook; The Copper Development Association,New York, 1995.

25. NUREG/CR-6239 ORNEL/Sub/94-SD427/2/V1, Volume 1: “Surveyof Strong Motion Earthquake Effects on Thermal Power Plants inCalifornia with Emphasis on Piping Systems.”

26. NUREG/CR–6358 entitled ‘‘Assessment of United States IndustryStructural Codes and Standards for Application to Advanced NuclearPower Reactors.”

27. Electric Power Research Institute (EPRI), Recommended PipingSeismic Adequacy Criteria Based on Performance Duringand afterEarthquakes, Report NP-5617, January 1988.

28. Electric Power Research Inst., (EPRI)-Report-NP-6593, “The NewZealand earthquake of March 2, 1987: Effects on electric power andindustrial facilities” 1989 Nov 01.

29. EPRI, NP-7500-SL, The October 17, 1989 Loma Prieta Earthquake:Effects onselected power and industrial facilities, September 1991.

30. Welding Research Concil (WRC) Bulleting 423, “Evaluation OfSeismic Response Data For Piping”, by Gerry C. Slagis- July 1997.

36-26 • Chapter 36

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31. Electric Power Research Inst. (EPRI) “Piping and Fitting DynamicReliability Programs (PFDRP),” EPRI Contract RP 1543-15.

32. ASME RTP-1, Reinforced Thermoset Plastic Corrosion-ResistantEquipment, 2011.

GENERAL REFERENCES

API 526, Flanged Steel Pressure Relief Valves; The American PetroleumInstitute.

API 570, Piping Inspection Code: Inspection Repair, Alteration, andRerating of In-Service Piping Systems; The American PetroleumInstitute.

API 594, Wafer and Wafer-Lug Check Valves; The American PetroleumInstitute.

API 599, Metal Plug Valves—Flanged and Welding Ends; The AmericanPetroleum Institute.

API 600, Steel Gate Valves—Flanged, Threaded and Butt-Welding EndsBolted and Pressure Seal Bonnets; The American PetroleumInstitute.

API 602, Compact Steel Gate Valves — Flanged, Threaded, Welding andExtended Body Ends, The American Petroleum Institute.

API 603, Class 150, Cast, Corrosion-Resistant, Flanged-End GateValves, The American Petroleum Institute.

API 608, Metal Ball Valves — Flanged, Threaded, and Butt-WeldingEnds, The American Petroleum Institute.

API 609, Butterfly Valves: Double Flanged, Lug- and Water-Type, TheAmerican Petroleum Institute.

ASME Boiler and Pressure Vessel Code Section I, Power Boilers, TheAmerican Society of Mechanical Engineers.

ASME Boiler and Pressure Vessel Code Section II, Part A, Materials,Ferrous Material Specifications, The American Society ofMechanical Engineers.

ASME Boiler and Pressure Vessel Code Section II, Part B, Materials,Nonferrous Material Specifications; The American Society ofMechanical Engineers.

ASME Boiler and Pressure Vessel Code Section III, Rules forConstruction of Nuclear Power Plant Components; The AmericanSociety of Mechanical Engineers.

ASME Boiler and Pressure Vessel Code Section VIII, Division 1,Pressure Vessels; The American Society of Mechanical Engineers.

ASME Boiler and Pressure Vessel Code Section VIII, Division 2,Pressure Vessels, Alternative Rules; The American Society ofMechanical Engineers.

ASME Boiler and Pressure Vessel Code Section IX, Welding and BrazingQualifications; The American Society of Mechanical Engineers.

ASME B31.1, Power Piping; The American Society of MechanicalEngineers.

ASME B31.3, Process Piping; The American Society of MechanicalEngineers.

ASME B31.4, Liquid Transportation Systems for Hydrocarbons, LiquidPetroleum Gas, Anhydrous Ammonia, and Alcohols; The AmericanSociety of Mechanical Engineers.

ASME B31.5, Refrigeration Piping; The American Society ofMechanical Engineers.

ASME B31.8, Gas Transmission and Distribution Piping Systems; TheAmerican Society of Mechanical Engineers.

ASME B31.9, Building Services Piping; The American Society ofMechanical Engineers.

ASME B31J, Standard Method to Develop Stress Intensification andFlexibility Factors for Piping Components; The American Society ofMechanical Engineers; under development.

ASME B16.1, Cast Iron Pipe Flanges and Flanged Fittings; AmericanNational Standards Institute.

ASME B1.20.1, Pipe Threads, General Purpose (Inch); The AmericanSociety of Mechanical Engineers.

ASME B16.3, Malleable Iron Threaded Fittings; The American Societyof Mechanical Engineers.

ASME B16.4, Gray Iron Threaded Fittings, The American Society ofMechanical Engineers.

ASME B16.5, Pipe Flanges and Flanged Fittings, The American Societyof Mechanical Engineers.

ASME B16.9, Factory-Made Wrought-Steel Butt welding Fittings, TheAmerican Society of Mechanical Engineers.

ASME B16.10, Face-to-Face and End-to-End Dimensions of Valves, TheAmerican Society of Mechanical Engineers.

ASME B16.11, Forged Steel Fittings, Socket-Welding and Threaded, TheAmerican Society of Mechanical Engineers.

ASME B16.14, Ferrous Pipe Plugs, Bushings, and Locknuts with PipeThreads, The American Society of Mechanical Engineers.

ASME B16.15, Cast Bronze Threaded Fittings, Classes 125 and 250, TheAmerican Society of Mechanical Engineers.

ASME B16.18, Cast Copper-Alloy Solder-Joint Pressure Fittings, TheAmerican Society of Mechanical Engineers.

ASME B16.22, Wrought Copper and Copper-Alloy Solder-Joint PressureFittings, The American Society of Mechanical Engineers.

ASME B16.24, Bronze Pipe Flanges and Flanged Fittings, Classes 150,300, 400, 600, 900, 1500, and 2500 and Flanged Fittings, Classes150 and 300; The American Society of Mechanical Engineers.

ASME B16.26, Cast Copper Alloy Fittings for Flared Copper Tubes, TheAmerican Society of Mechanical Engineers.

ASME B16.28, Wrought-Steel Buttwelding Short Radius Elbows andReturns, The American Society of Mechanical Engineers.

ASME B16.34, Valves—Flanged, Threaded, and Welding End, TheAmerican Society of Mechanical Engineers.

ASME B16.36, Orifice Flanges, Classes 300, 600, 600, 900, 1500, and2500; The American Society of Mechanical Engineers.

ASME B16.39, Malleable Iron Threaded Pipe Unions, Classes 150, 250,and 300; The American Society of Mechanical Engineers.

ASME B16.42, Ductile Iron Pipe Flanges and Flanged Fittings, Classes150 and 300; The American Society of Mechanical Engineers.

ASME B16.47, Large Diameter Steel Flanges, NPS 26 Through NPS 60;The American Society of Mechanical Engineers.

ASME B16.48, Steel Line Blanks; The American Society of MechanicalEngineers.

AWWA C110, Ductile-Iron and Gray-Iron Fittings, 3 Inch Through 48Inch (75 mm Through 1200 mm), for Water and Other Liquids;American Water Works Association.

AWWA C115, Flanged Ductile-Iron with Ductile-Iron or Gray-IronThreaded Flanges, American Water Works Association.

AWWA C207, Steel Pipe Flanges for Water Works Service, Sizes 4 InchThrough 144 Inch (100 mm Through 3,600 mm); American WaterWorks Association.


PROPRIETARY A

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AWWA C208, Dimensions for Fabricated Steel Water Pipe Fittings,American Water Works Association.

AWWA C 500, Metal-Seated Gate Valves for Water Supply Service,American Water Works Associations.

AWWA C 504, Rubber-Seated Butterfly Valves, American Water WorksAssociation.

MSS SP-42, Class 150 Corrosion-Resistant Gate, Globe, Angle, andCheck Valves With Flanged and Butt weld Ends; ManufacturersStandardization Society of the Valve and Fittings Industry, Inc.

MSS SP-43, Wrought Stainless Steel Butt welding Fittings, Man-ufacturers Standardization Society of the Valve and FittingsIndustry, Inc.

MSS SP-44, Steel Pipe Line Flanges, Manufacturers StandardizationSociety of the Valve and Fittings Industry, Inc.

MSS SP-51, Class 150 LW Corrosion-Resistant Cast Flanges andFlanged Fittings, Manufacturers Standardization Society of the Valveand Fittings Industry, Inc.

MSS SP-65, High-Pressure Chemical Industry Flanges and ThreadedStubs for Use with Lens Gaskets, Manufacturers StandardizationSociety of the Valve and Fittings Industry, Inc.

MSS SP-70, Cast Iron Gate Valves, Flanged and Threaded Ends,Manufacturers Standardization Society of the Valve and FittingsIndustry, Inc.

MSS SP-71, Cast Iron Swing Check Valves, Flanged and Threaded Ends,Manufacturers Standardization Society of the Valve and FittingsIndustry, Inc.

MSS SP-72, Ball Valves With Flanged or Buttwelding Ends for GeneralService; Manufacturers Standardization Society of the Valve andFittings Industry, Inc.

MSS SP-73, Brazing Joints for copper and copper Alloy pressure fittings.

MSS SP-75, Specifications for High Test Wrought Buttwelding Fittings,Manufacturers Standardization Society of the Valve and FittingsIndustry, Inc.

MSS SP-79, Socket-Welding Reducer Inserts; Manufacturers StandardizationSociety of the Valve and Fittings Industry, Inc.

MSS SP-80, Bronze Gate, Globe, Angle, and Check Valves, ManufacturersStandardization Society of the Valve and Fittings Industry, Inc.

MSS SP-81, Stainless Steel, Bonnetless, Flanged, Knife Gate Valves,Manufacturers Standardization Society of the Valve and FittingsIndustry, Inc.

MSS SP-83, Class 3000 Steel Pipe Unions, Socket-Welding andThreaded; Manufacturers Standardization Society of the Valve andFittings Industry, Inc.

MSS SP-85, Cast Iron Globe and Angle Valves, Flanged and ThreadedEnds, Manufacturers Standardization Society of the Valve andFittings Industry, Inc.

MSS SP-88, Diaphragm-Type Valves, Manufacturers StandardizationSociety of the Valve and Fittings Industry, Inc.

MSS SP-95, Swage (d) Nipples and Bull Plugs, ManufacturersStandardization Society of the Valve and Fittings Industry, Inc.

MSS SP-97, Integrally Reinforced Forged Branch Outlet Fittings —Socket Welding, Threaded, and Buttwelding Ends; ManufacturersStandardization Society of the Valve and Fittings Industry, Inc.

MSS SP-105, Instrument Valves for Code Applications, ManufacturersStandardization Society of the Valve and Fittings Industry, Inc.

MSS SP-58, Pipe Hangers and Supports—Materials, Design, andManufacture; Manufacturers Standardization Society of the Valveand Fittings Industry, Inc.

SAE J513, Refrigeration Tube Fittings — General Specifications; Societyof Automotive Engineers.

SAE J514, Hydraulic Tube Fittings; Society of Automotive Engineers.

SAE J518, Hydraulic Flange Tube, Pipe, and Hose Connections, Four-Bolt Split Flanged Type; Society of Automotive Engineers.

WRC 107, Wichman, K., Hopper, A., and Mershon, J. (1979). “LocalStresses in Spherical and Cylindrical Shells due to ExternalLoadings,” Welding Research Council, Bulletin 107, New York.

WRC 297, Mershon, J., Mokhtarian, K., Ranjan, G., and Rodabaugh, E.(1984). “Local Stresses in Cylindrical Shells due to ExternalLoadings on Nozzles—Supplement to WRC Bulletin No. 107,”Welding Research Council, Bulletin 297, New York.

36-28 • Chapter 36

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