DNVGL-RP-0034 Steel forgings for subsea applications · PDF fileRecommended practice...

RECOMMENDED PRACTICE
DNVGL-RP-0034 Edition February 2015
Steel forgings for subsea applications

DNV GL AS

The electronic pdf version of this document found through http://www.dnvgl.com is the officially binding version. The documents are available free of charge in PDF format.

FOREWORD
DNV GL recommended practices contain sound engineering practice and guidance.
© DNV GL AS

Any comments may be sent by e-mail to [email protected]

This service document has been prepared based on available knowledge, technology and/or information at the time of issuance of this document. The use of thisdocument by others than DNV GL is at the user's sole risk. DNV GL does not accept any liability or responsibility for loss or damages resulting from any use ofthis document.

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Acknowledgements:This recommended practice was developed by a Joint Industry Project (JIP). The work was performed by DNV GL and discussed in regular project meetings and workshops with individuals from the participating companies. They are hereby acknowledged for their valuable and constructive input. In case consensus has not been achievable, DNV GL has sought to provide acceptable compromise.

Sponsors of the JIP included the following organisations:

Further organisations have participated in the review process. DNV GL is grateful for the valuable co-operations and discussions with individuals in these organisations.

Aker Solutions Brück Celsa ChevronDet Norske Dril-Quip Ellwood Group EniExxonMobil FMC Frisa GEJapan Steel Works Lundin OneSubsea PetrobrasRingmill Scana Subsea Shell StatoilTotal

Recommended practice DNVGL-RP-0034 – Edition February 2015 Page 3

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CONTENTS
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Sec.1 General ......................................................................................................... 61.1 Introduction ...........................................................................................61.2 Scope and application ............................................................................61.3 Steel forging classes ..............................................................................61.4 Purchase order information....................................................................71.5 Normative and informative references ...................................................71.6 Definitions..............................................................................................91.7 Verbal forms...........................................................................................91.8 Abbreviations .........................................................................................9

Sec.2 Quality assurance and quality control ......................................................... 112.1 Quality management system ................................................................112.2 Manufacturing procedure specification.................................................112.3 Inspection and test plan.......................................................................122.4 Marking and traceability.......................................................................122.5 Certification and documentation ..........................................................12

Sec.3 Technical provisions.................................................................................... 143.1 Manufacturing practices .......................................................................14

3.1.1 General ......................................................................................143.1.2 Melting, refining, and casting.........................................................143.1.3 Forging.......................................................................................143.1.4 Heat treatment............................................................................15

3.2 Chemical composition...........................................................................153.2.1 Heat analysis...............................................................................153.2.2 Product analysis...........................................................................15

3.3 Mechanical testing ...............................................................................163.3.1 Test laboratories..........................................................................163.3.2 Test material...............................................................................163.3.3 Test sampling..............................................................................163.3.4 Test methods ..............................................................................173.3.5 Mechanical properties ...................................................................173.3.6 Hardness testing..........................................................................173.3.7 Re-testing...................................................................................183.3.8 Testing after simulated post weld heat treatment ............................18

3.4 Metallographic examination .................................................................183.5 Non-destructive testing........................................................................18

3.5.1 General ......................................................................................183.5.2 Visual testing ..............................................................................193.5.3 Magnetic particle testing ...............................................................193.5.4 Ultrasonic testing .........................................................................19

3.6 Dimensional inspection ........................................................................203.7 Repair ..................................................................................................20

Sec.4 Manufacturing procedure qualification........................................................ 214.1 General ................................................................................................214.2 Qualification testing .............................................................................21

4.2.1 Chemical composition ...................................................................21


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4.2.2 Tensile and Charpy V-notch testing ................................................21
4.2.3 Hardness testing..........................................................................224.2.4 Testing after simulated post weld heat treatment .............................224.2.5 Metallographic examination ...........................................................224.2.6 Fracture toughness testing ............................................................234.2.7 Non-destructive testing.................................................................234.2.8 Dimensional inspection .................................................................23

4.3 Validity.................................................................................................23


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SECTION 1 GENERAL
1.1 IntroductionThis recommended practice (RP) contains criteria, technical requirements and guidance on qualification, manufacture and testing of carbon and low alloy steel forgings for subsea applications.

The RP has been written for general world-wide application. Governmental regulations may include requirements in excess of the provisions given by this RP.

The objectives of this RP are to:

a) provide an internationally acceptable and harmonised standard for carbon and low alloy steel forgingsb) provide for reduced lead time, enhanced stock keeping and interchangeability c) provide consistent quality to increase reliability/integrity of subsea equipmentd) simplify the risk assessment processe) serve as a contractual reference document between manufacturers and purchasers f) serve as a guideline for designers, suppliers, purchasers and regulators g) comply with and complement existing industry codes for subsea equipment.

The RP is divided into four main sections:

— Sec.1 General: Contains introduction, scope and application, information to be supplied by purchaser, normative and informative references, definitions and abbreviations.

— Sec.2 Quality assurance and quality control: Contains requirements for quality management system, manufacturing procedure specification, inspection and test plan, marking and traceability, documentation and certification.

— Sec.3 Technical provisions: Contains requirements for manufacture, testing and inspection of production parts.

— Sec.4 Manufacturing procedure qualification: Contains requirements for qualification of manufacturing processes, methods, procedures and validity.

1.2 Scope and applicationThe steel forgings covered herein are intended for components in subsea equipment. Typical applications include:

a) subsea wellhead and tree equipment as per ISO 13628-4 or API 17Db) completion/workover riser systems as per ISO 13628-7 or API 17Gc) subsea structures and manifolds as per ISO 13628-15 or API 17Pd) flexible pipe as per ISO 13628-11 or API 17Be) drill-through equipment as per ISO 13533 or API 16A.

The material grades covered are carbon steels, micro-alloyed steels, low alloy steels and modified grades thereof as per material groups 1 and 2 in API 20B.

This RP is not intended to inhibit a vendor from offering, or the purchaser from accepting, alternative materials or manufacturing processes. This can be particularly applicable where there is innovative or developing technology. Where an alternative is offered, it is the responsibility of the vendor to identify any variations from this RP and provide details to the purchaser.

1.3 Steel forging classesThis RP establishes requirements for three steel forging classes (SFC) designated SFC 1, SFC 2, and SFC 3. These SFC designations define different levels of forged product technical, quality and qualification requirements.

All classes are intended for equipment that shall meet product specification level (PSL) 3 and 3G


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requirements in the referenced industry codes, e.g. ISO 10423 or API 6A.The three forging classes reflect
increasing criticality as defined by the end user and, hence, increasing requirements from SFC 1 to SFC 3:

— SFC 1 is intended for less critical components, e.g. components that are not subjected to continuous exposure to flowing hydrocarbons or components with simple shapes.

— SFC 2 is intended for pressure containing and/or load bearing components that are of significant enough size and complexity to warrant additional mechanical testing and surveillance.

— SFC 3 is intended for fatigue sensitive pressure containing and/or load bearing components.

1.4 Purchase order informationThe purchaser shall provide at least the following information in the order:

a) that the forging(s) shall be made according to this RP

b) the steel forging class (SFC);

c) the steel designation (name or number);

d) the quantity of forgings required;

e) the drawing number(s) containing the dimensions, tolerances and surface finish;

f) the position and thickness of the critical section(s) in the part;

g) the minimum design temperature (MDT)/Charpy V-notch (CVN) test temperature;

h) the specified minimum yield strength (SMYS);

i) the marking requirements for the forging(s);

j) the type of certification document;

k) whether the forging(s) shall be ISO 15156-2 or NACE MR0175 compliant;

l) whether the forging(s) shall be subjected to simulated post weld heat treatment (SPWHT);

m) whether forging plan/sketch shall be submitted for review or approval prior to production;

n) whether test sample drawing shall be submitted for review or approval prior to production;

o) whether ultrasonic testing (UT) procedure and scan plan shall be submitted for review or approval prior to production;

p) whether magnetic particle testing (MT) procedure and test coverage description shall be submitted for review or approval prior to production;

q) whether manufacturing procedure specification (MPS) shall be submitted for review or approval prior to production;

r) whether inspection and test plan (ITP) shall be submitted for mark-up, review or approval prior to production;

s) whether manufacturing procedure qualification (MPQ) report shall be submitted for review or approval prior to production;

t) whether any additional requirements shall apply.

1.5 Normative and informative referencesThe codes and standards in Table 1-1 and Table 1-2 include provisions and guidance which, through reference in this text, constitute provisions and guidance of this RP. The latest edition applies unless dated references are given.

Other recognised codes and standards may be used provided it can be demonstrated that these meet or exceed the requirements of the referenced codes and standards.

Any deviations, exceptions and modifications to the codes and standards shall be documented and agreed between the manufacturer and purchaser.


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Table 1-1 Normative references

API RP 6HT Heat Treatment and Testing of Carbon and Low Alloy Steel Large Cross Section and Critical Section Components

API Spec 20B Open Die Shaped Forgings for Use in the Petroleum and Natural Gas IndustryACCP-CP-1 American Society for Nondestructive Testing Central Certification Program ASME BPVC-V ASME Boiler and Pressure Vessel Code (BPVC), Section V: Nondestructive ExaminationASTM A370 Standard Test Methods and Definitions for Mechanical Testing of Steel ProductsASTM A388 Standard Practice for Ultrasonic Examination of Steel ForgingsASTM A604 Standard Practice for Macroetch Testing of Consumable Electrode Remelted Steel Bars

and BilletsASTM A694 Standard Specification for Carbon and Alloy Steel Forgings for Pipe Flanges, Fittings,

Valves, and Parts for High-Pressure Transmission ServiceASTM A707 Standard Specification for Forged Carbon and Alloy Steel Flanges for Low-Temperature

ServiceASTM A751 Standard Test Methods, Practices, and Terminology for Chemical Analysis of Steel

ProductsASTM A788 Standard Specification for Steel Forgings, General RequirementsASTM E45 Standard Test Methods for Determining the Inclusion Content of SteelASTM E110 Standard Test Method for Indentation Hardness of Metallic

Materials by Portable Hardness TestersASTM E112 Standard Test Methods for Determining Average Grain SizeASTM E381 Standard Method of Macroetch Testing Steel Bars, Billets, Blooms, and ForgingsASTM E709 Standard Guide for Magnetic Particle TestingASTM E1820 Standard Test Methods for Measurement of Fracture ToughnessEN 10204 Metallic products - Types of inspection documentsISO 643 Steels - Micrographic determination of the apparent grain sizeISO 9001 Quality Management Systems – RequirementsISO 9712 Non-destructive testing - Qualification and certification of NDT personnelISO 10423/API Spec 6A Petroleum and natural gas industries - Drilling and production equipment - Wellhead and

christmas tree equipment/Specification for Wellhead and Christmas Tree equipmentISO 10474 Steel and steel products - Inspection documentsISO 12135 Metallic materials - Unified method of test for the determination of quasistatic fracture

toughnessISO 15156-2/NACE MR0175 Petroleum and natural gas industries - Materials for use in H2S-containing environments

in oil and gas production - Part 2: Cracking-resistant carbon and low-alloy steels, and the use of cast irons/Petroleum and natural gas industries - Materials for use in H2S-containing environments in oil and gas production

ISO/IEC 17020 Conformity assessment - General criteria for the operation of various types of bodies performing inspection

ISO/IEC 17025 General requirements for the competence of testing and calibration laboratories


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1.6 Definitions

1.7 Verbal forms

1.8 Abbreviations

Table 1-2 Informative references

API RP 17B Recommended Practice for Flexible PipeAPI Spec 16A Specification for Drill Through EquipmentISO 13533 Petroleum and natural gas industries - Drilling and production equipment - Drill-through

equipmentISO 13628-1/API RP 17A Petroleum and natural gas industries - Design and operation of subsea

production systems - Part 1: General requirements and recommendations/Design and Operation of Subsea Production Systems-General Requirements and Recommendations

ISO 13628-4/API Spec 17D Petroleum and natural gas industries - Design and operation of subsea production systems - Part 4: Subsea wellhead and tree equipment/Design and Operation of Subsea Production Systems-Subsea Wellhead and Tree Equipment

ISO 13628-7/API RP 17G Petroleum and natural gas industries - Design and operation of subsea production systems - Part 7: Completion/workover riser systems/Recommended Practice for Completion/Workover Risers

ISO 13628-11 Petroleum and natural gas industries - Design and operation of subsea production systems - Part 11: Flexible pipe systems for subsea and marine applications

ISO 13628-15/API RP 17P Petroleum and natural gas industries - Design and operation of subsea production systems - Part 15: Subsea structures and manifolds/Design and Operation of Subsea Production Systems - Subsea Structures and Manifolds

Table 1-3 Definitions

critical section(s) section(s) of the forging in which mechanical properties have to meet the specified minimum requirements and are deemed critical to the design and safe operation of the component.

Table 1-4 Verbal forms

shall verbal form used to indicate requirements strictly to be followed in order to conform to the document.should verbal form used to indicate that among several possibilities one is recommended as particularly suitable,

without mentioning or excluding others, or that a certain course of action is preferred but not necessarily required.

may verbal form used to indicate a course of action permissible within the limits of the document.

Table 1-5 Abbreviations

CE (IIW) carbon equivalent (international institute of welding)CS carbon steelCTOD crack tip opening displacementCVN Charpy V-notchDAC distance amplitude correctionDGS distance gain-sizeEAF electric arc furnaceESR electro slag re-meltingFBH flat bottom hole ITP inspection and test planLAS low alloy steelLR ladle refiningMDT minimum design temperatureMPQ manufacturing procedure qualificationMPS manufacturing procedure specificationMT magnetic particle testing


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MTR material test reportNDT non-destructive testingPWHT post weld heat treatmentQMS quality management systemRP recommended practiceSFC steel forging classSMYS specified minimum yield strengthSPWHT simulated post weld heat treatmentUT ultrasonic testingVAR vacuum arc re-meltingVD vacuum degassingVT visual testing

Table 1-5 Abbreviations (Continued)


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SECTION 2 QUALITY ASSURANCE AND QUALITY CONTROL
2.1 Quality management systemThe forging manufacturers and steel manufacturers shall have a certified quality management system (QMS) conforming to ISO 9001.

2.2 Manufacturing procedure specificationAll production shall be based on an manufacturing procedure specification (MPS) established by the forging manufacturer. The MPS shall describe how the specified properties will be achieved and verified. The MPS shall address all factors that affect the quality and reliability of production including all subcontractors applied. Every principal production step from starting material to shipment of finished product(s) shall be addressed. References to the detailed procedures used for the execution of all steps shall be included.

As a minimum, the MPS shall include the information in Table 2-1.

Table 2-1 Content of MPS

1) General a) A descriptive title and a unique identification number with revision controlb) Description of product(s) and size range(s)c) Reference to applicable standards and specificationsd) Reference to MPQ(s)

2) Starting materials a) Steel manufacturer, steel grade, melt practice, refining and casting methodb) Specification for chemical composition and carbon equivalent (CE)c) Ingot typed) Methods and practices for ingot discard

3) Forging a) Forging method, e.g. open die, closed die or ring rollingb) Forging press/equipment capacity, as applicablec) Hot work temperature range and method of temperature monitoring during forgingd) Description of basic forging steps, i.e. sequence of upsetting, drawing, etce) Forging reduction calculation method for each step and minimum overall forging reduction

ratiof) Sketch of forging(s) including prolongation, if used, in as-forged condition

4) Heat treatment a) Heat treat condition of supply, e.g. quenched and temperedb) Sketch of forging(s) including prolongation, if used, at time of heat treatment, if any

different from as-forged geometry. Finished geometry, if known, shall be given with dashed lines

c) Maximum thickness of forging(s) at time of heat treatmentd) Description of furnace loading practice with typical sketch(es) showing maximum loading

weight, location and minimum spacing of parts in the furnace, location of prolongation or sacrificial part and location of contact thermocouples/heat sinks

e) Description of heat treatment cycles, temperatures and timesf) Minimum quench tank size/volumeg) Quenching medium and type of agitationh) Quenching medium start and finish temperature and maximum transfer time to quenchi) Maximum surface metal temperature at removal from quench tank including how and when

temperature is measured5) Mechanical testing, metallographic examination, and product analysis

a) Specified tensile, Charpy V-notch (CVN) and surface hardness testing b) Sketch showing sampling position and specimen orientation in prolongation or sacrificial

forging, as applicablec) Sketch with the locations for surface hardness testingd) Grain size determinatione) Inclusion rating for SFC 3f) Chemical composition determined as product analysis for SFC 3


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2.3 Inspection and test planThe forging manufacturer shall establish an inspection and test plan (ITP) for SFC 2 and SFC 3. The ITP shall have a reference to the relevant MPS and shall list the sequence of activities contained in the MPS. Manufacturers may use their own ITP format, but it shall as a minimum include:

a) all principal production, inspection and testing activities b) location of activityc) associated procedure or specification including acceptance criteria governing the activityd) verifying document to be used for recording inspection and test resultse) forging manufacturer’s intervention activitiesf) columns for intervention by purchaser and 3rd party.

2.4 Marking and traceabilityThe forgings shall be marked to ensure full traceability to the heat or re-melt ingot (as applicable), heat treatment lot and the certificate representing the forging. Additional marking shall be as specified in the purchase order.

Each forging shall be marked with a low stress marking method on a position as stated in the MPS.

2.5 Certification and documentationCertification of production forgings shall be as specified by the purchaser. Any of the following certification documents are applicable:

— A manufacturer’s test report (MTR) giving the results of all specified tests and inspections.— An inspection document type 3.1 or 3.2 according to ISO 10474 or EN 10204.

The certificates shall be supplied by the manufacturer to the purchaser and shall, as a minimum, give the following particulars:

a) purchaser’s name, order number and part numberb) forging manufacturer’s name and order numberc) description of forging(s) including quantity and drawing number(s)d) reference to this RPe) steel designation and SFCf) reference to the applicable MPSg) steelmaker’s nameh) steelmaking process including secondary refiningi) forging method and forging reduction ratioj) name of heat treat subcontractor, if applicablek) heat number(s) and heat treat lot number(s)l) Heat treatment temperatures, soaking times, quenching medium and transfer time from furnace to

quench tankm) heat analysis and, where applicable, product analysis

6) Non-destructive testing, as applicable

a) Visual testing

b) Magnetic particle testing, including sketch or description of test coverage

c) Ultrasonic testing, including scan plan

7) Dimensional control and marking

a) Dimensional controlb) Method, extent, and position of marking

8) Final certification a) Type of certificateb) Associated records and documentation

Table 2-1 Content of MPS (Continued)


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n) prolongation or sacrificial part dimensions
o) results of tensile, CVN, surface hardness, metallographic and any other testing requiredp) NDT report(s)q) marking of forging(s).

The certificates shall be accompanied by documentation and records as follows:

a) heat treatment chart(s) and furnace loading sketch(es)b) test plan/sketch showing locations for tensile, CVN, surface hardness, metallographic and any other

testing requiredc) NDT procedure(s)d) dimensional inspection report(s)e) for SFC 2 and SFC 3, copy of certificate(s) from steelmaker.

The manufacturer shall maintain documentation and records of relevant manufacturing procedure qualification (MPQ).


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SECTION 3 TECHNICAL PROVISIONS
3.1 Manufacturing practices

3.1.1 GeneralAll manufacturing shall be based on the MPS, the associated MPQ (for SFC 2 and SFC 3), and the requirements of this RP.

3.1.2 Melting, refining, and casting3.1.2.1 The steel shall be melted using the electric arc furnace (EAF) followed by secondary refining such as ladle refining (LR) and vacuum degassing (VD). Secondary re-melt processes such as electro slag re-melting (ESR) and vacuum arc re-melting (VAR) may also be used.

3.1.2.2 The steel shall be fully killed and made to a fine grain practice. See also [3.4].

3.1.2.3 The steel for SFC 3 shall be treated for inclusion shape control. When Ca treatment is used, Ca shall not exceed 0.005%. See also [3.4].

3.1.2.4 The steel shall be ingot cast with bottom pouring, ingot cast with top pouring in vacuum, or continuous cast. Adequate top and bottom ingot discards shall be made to ensure freedom from piping and harmful segregations in the finished forgings. Surface and skin defects, which may be detrimental during the subsequent working and forming operations, shall be removed.

3.1.2.5 Repair by welding on ingots, blooms or billets shall not be permitted.

3.1.2.6 Melting, refining and casting practices shall be as stated in the MPS.

3.1.3 Forging3.1.3.1 Forgings shall be made by any of the following methods: Open die, closed die or ring rolling.

3.1.3.2 The material shall be hot worked, and shall be forged as close as practical to the finished shape and size.

3.1.3.3 The hot work temperature shall be monitored during the forging process by pyrometer or equivalent equipment.

3.1.3.4 The overall forging (total hot work) reduction ratio shall be minimum 4.0:1 for all classes, with the following considerations:

a) The initial free upsetting operations of the as cast ingot shall not be considered as part of the overall forging reduction ratio.

b) Upsetting following cogging or drawing may be considered as part of the overall forging reduction ratio. If upsetting following cogging or drawing is to be considered, the overall forging reduction ratio shall be minimum 6.0:1.

c) For ring rolling or mandrel forging, punching or piercing of holes shall not be considered as part of the overall forging reduction ratio.

d) The overall reduction ratio shall be sufficient to produce a wrought structure throughout the entire part.

3.1.3.5 The hot work reduction ratio for a single hot work operation and the total hot work reduction ratio shall be calculated according to API 20B.

3.1.3.6 For ring rolling or mandrel forging, the initial cross-sectional area shall be as-punched or pierced wall thickness times as-punched or pierced height. The final cross-sectional area shall be final wall thickness times final height.

3.1.3.7 For closed die forging, the reduction ratio shall meet the requirement of this RP prior to the closed die operation.

3.1.3.8 Repair by welding on forgings shall not be permitted.


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3.1.4 Heat treatment
3.1.4.1 GeneralForgings shall be supplied in the heat treat condition as stated in the MPS.

Where forgings are to be quenched and tempered and cannot be hot worked close to shape, they shall be rough machined as close as practical to final shape and size prior to heat treatment.

3.1.4.2 Heat treatment practicesHeat treatment practices shall comply with the requirements in API 6HT and the following additional requirements:

a) Qualification of heat treatment equipment shall be according to ISO 10423 or API 6A, Annex M.b) No stacking of SFC 3 forgings shall be allowed during heat treat operations.c) In the case of SFC 1 and SFC 2 ring forgings and bars, etc, stacking shall be allowed provided that

— spacers or cradle between layers are used — proper agitation is applied for heat transfer — the stacking is shown in the MPS— the stacking was used during heat treatment for MPQ of SFC 2.

d) In cases where the 90 seconds transfer time from furnace to quench tank is not achievable or applicable due to hardenability/thickness, transfer time shall be as qualified and stated in the MPS.

e) The temperature monitoring for SFC 2 and SFC 3 shall be done by the attached thermocouple monitoring method described in API 6HT.

f) Surface metal temperature at removal from quench tank shall be measured.

3.1.4.3 Simulated post weld heat treatmentWhere forgings are subjected to subsequent welding and post weld heat treatment (PWHT), as specified by the purchaser, a SPWHT shall be carried out. See [3.3.8].

3.2 Chemical composition

3.2.1 Heat analysisHeat analysis shall be performed for all classes according to ASTM A751. The heat analysis shall comply with the specified limits and the requirements given in Table 3-1.

3.2.2 Product analysisProduct analysis shall be performed for SFC 3 according to ASTM A751. The product analysis shall comply with the specified limits and the requirements in Table 3-1 subject to permissible variations as specified in ASTM A788. Product analysis of nitrogen, hydrogen and oxygen is not required.

Table 3-1 Chemical composition limits in weight %

Element 1) SFC 1 SFC 2 SFC 3

Sulphur (S) 0.010 max. 0.010 max. 0.005 max.

Phosphorus (P) 0.015 max. 0.015 max. 0.010 max.

Aluminium (Al) 2) 0.055 max. 0.055 max. 0.055 max.

Calcium (Ca) - - 0.005 max.

Vanadium (V) 3) 4) 0.06 max. 0.06 max. 0.03 max.

Niobium (Nb) 3) 4) 0.02 max. 0.02 max. 0.02 max.

Titanium (Ti) 0.025 max. 0.025 max. 0.025 max.

Tin (Sn) 0.02 max. 0.02 max. 0.015 max.

Antimony (Sb) 0.03 max. 0.03 max. 0.02 max.

Arsenic (As) 0.03 max. 0.03 max. 0.02 max.


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3.3 Mechanical testing

3.3.1 Test laboratoriesTest laboratories shall have a QMS conforming to ISO 17025 or equivalent. If the laboratory is not certified according to ISO 17025, the QMS shall be approved by the purchaser.

3.3.2 Test material3.3.2.1 Tensile and impact properties are required at the critical section(s). For this reason, test material for mechanical testing shall have a thickness representative of the critical section(s) of the part. The critical section(s) shall be determined by the equipment manufacturer in the product design and communicated to the forging manufacturer.

3.3.2.2 Test material for all classes shall be a prolongation, as defined in API 20B, or a sacrificial production part. Test material shall represent each heat, re-melt ingot (if applicable) and heat-treat lot.

3.3.2.3 Forging manufacturers shall take into account that extra test material is needed for SPWHT. Forging manufacturers shall also take into account the possibility of re-testing in establishing the minimum amount of test material required.

3.3.2.4 Test material shall be marked for identification.

3.3.3 Test sampling3.3.3.1 For SFC 1, one tensile and one set of three CVN specimens shall be taken for each position and orientation, as given in the applicable industry code.

For SFC 2 and SFC 3, one tensile and one set of three CVN specimens shall be taken for each position and orientation, as given in Table 3-2.

Lead (Pb) 0.010 max. 0.010 max. 0.010 max.

Bismuth (Bi) 0.010 max. 0.010 max. 0.010 max.

Boron (B) 5) 0.0010 max. 0.0010 max. 0.0005 max.

Nitrogen (N) 4) 0.012 max. 0.012 max. 0.012 max.

Hydrogen (H) 2 ppm max. 2 ppm max. 2 ppm max.

Oxygen (O) 25 ppm max. 25 ppm max. 25 ppm max.

CE (IIW) 6) 7) 0.48 max. 0.48 max. 0.48 max.1) Limits for elements such as carbon, manganese, silicon, chromium, nickel and molybdenum shall be as specified in the MPS. 2) Min. 0.020% Al (total content) unless other nitrogen binding elements are used, e.g. Nb, V or Ti. 3) Limit applies to forgings subjected to subsequent welding and PWHT.4) Not applicable for ASTM A707 L3.5) Boron shall not be intentionally added.6) CE (IIW) = C + Mn/6 + (Cu + Ni)/15 + (Cr + Mo + V)/57) Limit applies to CS forgings, typically ASTM A694 F60 and F65, subjected to welding without PWHT. Steels with CE > 0.45 shall have supporting weldability data for the thickness and composition under consideration demonstrating compliance with relevant hardness requirements.

Table 3-2 Position and orientation of specimens for production testing of SFC 2 and SFC 3

Thickness,T 1) Test specimen position 2) 3) Orientation 4) 5)

≤ 100 mm (4 in.) ½ T Longitudinal and transverse> 100 mm (4 in.) ¼ T and ½ T Longitudinal and transverse1) Thickness (T) is the thickness of the test material, i.e. critical section, at the time of heat treatment.2) Position ½ T is at the centre (solid forging) or mid-wall (hollow forging) thickness. Position ¼ T is one quarter thickness below heat treated surface. 3) Sampling of solid forgings when centre will be subsequently removed shall be at IDfinish instead of the ½ T position. 4) Test specimen orientations shall be as defined in ASTM A370. Specimens shall be taken in both directions, if geometry permits.5) For circular forgings such as rings and discs, longitudinal and tangential tests shall be used.

Table 3-1 Chemical composition limits in weight % (Continued)

Element 1) SFC 1 SFC 2 SFC 3


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3.3.3.2 Test specimens shall be positioned such that the tensile specimen middle gauge length and CVN
root is as follows:

a) for hollow forgings, T from any second surface

b) for solid forgings, ½ T from any second surface.

3.3.4 Test methods3.3.4.1 Tensile and CVN testing shall be performed according to the applicable standards given in ASTM A370.

3.3.4.2 Brinell or Rockwell hardness testing shall be performed according to the applicable standards given in ASTM A370 using a stationary machine. If stationary testing is impracticable, then portable hardness testing in accordance with ASTM E110 may be used.

3.3.5 Mechanical properties3.3.5.1 Tensile properties shall comply with the requirements specified in Table 3-3.

3.3.5.2 CVN test temperature shall be at minimum design temperature (MDT), as specified by the purchaser. CVN absorbed energy shall comply with the requirements in Table 3-4.

Guidance note:The MDT/CVN test temperature should correspond to one of the temperature classes specified in API 6A, e.g. U (-18°C/0°F), P (-29°C/-20°F), or L (-46°C/-50°F). The MDT should be agreed between the purchaser and end user.

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3.3.6 Hardness testing3.3.6.1 Both the test material surface and the forged or the rough machined surface of each production forging shall be hardness tested after quality heat treatment. The test locations and acceptance criteria (minimum and maximum hardness) shall be as stated in the MPS.

3.3.6.2 Maximum hardness shall be in accordance with ISO15156-2 or NACE MR0175 where components are intended for sour service.

3.3.6.3 For any component that can be exposed to cathodic protection, the hardness shall not exceed 35 HRC, 328 HBW or 350 HV 10.

Table 3-3 Tensile property requirements in longitudinal and transverse direction

Tensile property RequirementElongation in 50 mm (2 in), min., % 17 1)

Reduction in area, min., % 35Yield strength to tensile strength ratio (actual values), max. 0.90Actual yield strength, max., MPa (ksi) 950 (138)1) For compliance with requirements in API 17G, the minimum elongation in longitudinal direction shall be 18%.

Table 3-4 Minimum CVN absorbed energy in longitudinal and transverse direction

Specified minimum yield strength (SMYS)

SFC 1 SFC 2 and SFC 3Average Single Average Single

Up to 517 MPa (75 ksi)

40 J (30 ft-lb) 1)

30 J (22 ft-lb) 1)

50 J (37 ft-lb) 1)

38 J (28 ft-lb) 1)

Over 517 MPa (75 ksi)Up to 586 MPa (85 ksi)

60 J (44 ft-lb)

45 J (33 ft-lb)

Over 586 MPa (85 ksi)Up to 655 MPa (95 ksi)

70 J (52 ft-lb)

53 J (39 ft-lb)

1) For compliance with requirements in API 17G, the minimum absorbed energy in longitudinal direction shall be 60 J (44 ft-lb) average and 45J (33 ft-lb) single.


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3.3.7 Re-testing
3.3.7.1 If the results from tensile testing do not meet the specified requirements, two additional tensile tests may be made from the same test material. If both of these additional tests meet the requirements, the parts represented shall be accepted.

3.3.7.2 If the results from CVN testing do not meet the specified requirements, one additional set consisting of three specimens from the same test material may be tested. In order to accept the parts represented, after testing the additional set, the following conditions shall be satisfied simultaneously:

1) The average value of six specimens shall meet the specified minimum average value.2) Not more than two of six individual values shall be lower than the specified minimum average value.3) Not more than one of six individual values shall be lower than the specified minimum single value.

3.3.7.3 If the results from hardness testing do not meet the specified requirements, two additional readings may be taken in close proximity to the failed reading. If the average of the three readings meets the requirement and, in the case of parts for sour service, no individual reading is greater than 2 HRC above the specified value, the part shall be accepted.

3.3.7.4 If re-testing fails, the forgings represented may be subjected to re-heat treatment and then submitted to testing in accordance with [3.3]. In such cases, the forgings may be subjected to one additional full heat treatment cycle and may not be re-tempered more than twice. All the tests previously performed shall be repeated after re-heat treatment and the results shall meet the specified requirements.

3.3.8 Testing after simulated post weld heat treatment 3.3.8.1 Where a forging is subjected to subsequent welding and PWHT, as specified by the purchaser, sufficient material shall be removed from the test material and subjected to a SPWHT.

The time and temperature shall be the same as those used during MPQ or as specified by the purchaser. Total time at temperature shall consider inclusion of multiple heat treat cycles to accommodate weld repair.

3.3.8.2 Following the SPWHT, the material shall be tensile, CVN and surface hardness tested and shall meet the requirements of the applicable code and this RP.

3.4 Metallographic examinationThe prior austenite grain size for all classes shall be determined for each heat according to ISO 643 or ASTM E112. The prior austenite grain size shall be 5 or finer. Sampling position shall be ½ T for T ≤ 100 mm (4 in.) and ¼ T for T > 100 mm (4 in.).

Steel cleanliness for SFC 3 shall be determined for each heat according to ASTM E45, method A (Modified JK). Sampling position shall be ½ T for T ≤ 100 mm (4 in.) and ¼ T for T > 100 mm (4 in.). Inclusion rating limits shall meet the requirements in Table 3-5. If any oversize inclusions are present, they shall be recorded separately as per ASTM E45.

3.5 Non-destructive testing

3.5.1 General3.5.1.1 Companies performing magnetic particle testing (MT) and ultrasonic testing (UT) activities shall comply with ISO 17020 or its equivalent within non-destructive testing (NDT). Companies shall meet the requirements for Type A or Type B inspection bodies, as applicable.

Table 3-5 Modified JK inclusion rating limits for SFC 3

Type A B C DThin 1 1 1 1½Thick ½ ½ ½ 1


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3.5.1.2 Personnel responsible for MT and UT activities, including approval of procedures, shall be qualified
and certified to Level 3 in accordance with ISO 9712, ASNT Central Certification Program (ACCP) or equivalent third party certification system in the method(s) concerned.

3.5.1.3 Personnel performing MT and UT and interpretation of test results shall be qualified and certified to minimum Level 2 in accordance with ISO 9712, ASNT Central Certification Program (ACCP) or equivalent third party certification system in the method(s) concerned.

3.5.1.4 Personnel performing visual testing (VT) shall comply with vision requirements in accordance with the manufacturer's documented procedures that meet the applicable requirements of ISO 9712.

3.5.2 Visual testing3.5.2.1 All forgings shall be visually tested on all accessible surfaces in the final condition to be supplied to the purchaser. The light intensity at the examination surface shall be minimum 1000 lx. Forgings supplied in the black condition shall be de-scaled prior to VT.

3.5.2.2 Forgings shall be free from cracks, seams, laps, folds, pipe, segregation, underfills, scale or other imperfections, which due to their nature, degree or extent will interfere with the use of the forgings in the machining and fabrication of parts.

3.5.3 Magnetic particle testing3.5.3.1 All forgings shall be subjected to magnetic particle testing (MT) on the accessible surfaces in the final machined condition.

3.5.3.2 Where forgings are supplied in the black or rough machined condition, they shall be capable of meeting the MT requirements for parts in the final machined condition. This shall only apply to defects related to forging manufacturers’ activities, e.g. materials, forging and heat treatment. Forging manufacturers shall perform intermediate MT taking this into consideration. In such cases, the extent of testing and acceptance criteria shall be agreed with the purchaser.

3.5.3.3 MT in final machined condition shall be performed using continuous wet fluorescent technique in accordance with ASME BPVC-V Article 7 and ASTM E709 with the following exceptions: Prods, permanent magnets and DC magnets are not permitted. Copper electrodes or contact plates are not permitted.

3.5.3.4 If access limits the possibility for MT at a bore, UT shall be performed as given in [3.5.4.7].

3.5.3.5 MT acceptance criteria for SFC 1 and SFC 2 parts in the final machined condition shall be:

a) no relevant linear indication b) no relevant rounded indication with a major dimension equal to or greater than 3 mm (1/8 in)c) no more than ten relevant indications in any continuous 40 cm2 (6 in2) aread) four or more relevant indications in a line separated by less than 1.6 mm (1/16 in) (edge to edge) are

unacceptablee) no relevant indications in pressure contact sealing surfaces.

Relevant indication shall be as defined in ISO 10423 or API 6A.

3.5.3.6 MT acceptance criteria for SFC 3 parts in the final machined condition shall be no relevant indication, as defined in ISO 10423 or API 6A.

3.5.4 Ultrasonic testing3.5.4.1 All forgings shall be subjected to ultrasonic testing (UT) covering the entire volume. UT shall be performed in accordance with ASME BPVC-V Article 5 and ASTM A388. The instrument sensitivity shall be based on distance amplitude correction (DAC) curve. Alternatively, the distance gain-size (DGS) method may be used. The DGS method, if used, shall be verified on minimum two known reflectors of relevant size in a reference block of the same nominal chemical composition, heat treatment, surface finish and thickness as the forging(s) to be tested. The verification shall be documented.


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3.5.4.2 Scanning shall be performed from all accessible surfaces and at least from two perpendicular
directions. Forgings which cannot be examined axially using the straight-beam technique shall be scanned with the angle-beam technique in both axial directions.

3.5.4.3 Where the configuration of the forging limits complete coverage using straight beam probe, additional scanning with angle beam probe shall be performed. Alternatively, the machining of the part shall be such that areas where adequate ultrasonic testing is not possible will be removed during the final machining.

3.5.4.4 SFC 1: Scanning shall be in accordance with ASTM A388. Sensitivity setting for straight beam probes shall be in accordance with ISO 10423 or API 6A PSL 3. Sensitivity setting for angle beam probes shall be in accordance with ASTM A388 for cylindrical and hollow forgings. Acceptance criteria for straight beam and angle beam probe shall be in accordance with ISO 10423 or API 6A PSL 3.

3.5.4.5 SFC 2: As for SFC 1, with the addition that reference reflector sizes refer to wall thickness after final machining and not the actual thickness at time of examination.

3.5.4.6 SFC 3: As for SFC 2 with the addition that circumferential angle beam scanning, clockwise and counter-clockwise, shall be performed regardless of OD/ID ratio. If ID notch is not accessible, side drilled holes (SDH) may be used as reference reflector.

3.5.4.7 If access limits the possibility for MT at a bore, UT shall be performed on solid forgings before drilling of the bore, or before final machining of the bore. In such cases, the UT shall be based on a reflector size of flat bottom hole (FBH) Ø1.6 mm. No indications exceeding the reference are accepted in the location of final machined surface. The testing shall be defined in the scan plan and shall be unambiguously reported.

3.6 Dimensional inspectionAll forgings shall be inspected for dimensions and shall be according to drawings supplied by the purchaser.

3.7 RepairSurface defects may be removed by grinding or machining provided dimensional tolerances are maintained. The resulting grooves shall have a bottom radius of approximately three times the depth and shall be blended into the surrounding surface to avoid any sharp contours. Complete elimination of the defective material shall be verified by suitable NDT.

Repair by welding on forgings shall not be permitted.


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SECTION 4 MANUFACTURING PROCEDURE QUALIFICATION
4.1 General Manufacturing procedure qualification (MPQ) is not required for SFC 1.

For SFC 2 and SFC 3, the manufacturing processes, methods, and procedures shall be qualified by testing of a representative forging in order to:

— demonstrate that the manufacturing results in products meeting specified requirements— verify that the mechanical properties of the prolongation represent the critical cross section of the

production part, as agreed between the purchaser and the manufacturer— demonstrate the properties in the thickest cross section of the production part.

The qualification forging shall be representative in geometry and mass of production forgings and shall be produced in accordance with the MPS as specified in [2.2]. Regular production equipment shall be used for qualification and heat treatment furnaces used shall have maximum load.

Where stacking is allowed and intended used in production, see [3.1.4.2], the qualification forging shall be from the middle of the stack.

The qualification forging shall have an integral prolongation if prolongation testing is used in production. Where a prolongation is used, it shall have the same or smaller forging reduction ratio and the same thermal history as the critical section of the part.

Qualification forgings failing to meet the acceptance criteria specified in [4.2] shall be cause for re-evaluation of the processes and procedures used. A revision of the MPS and re-qualification is required.

4.2 Qualification testingThe qualification forging shall be subjected to testing on both the prolongation, if used, and the sacrificial part itself. Detailed requirements are given in [4.2.1] to [4.2.8]. Where production testing will be performed on a sacrificial part only, any reference to qualification testing on the prolongation shall be understood to mean qualification testing on the critical section of the sacrificial part.

All test results shall be documented.

4.2.1 Chemical compositionThe chemical composition shall be determined as heat and product analysis for both SFC 2 and SFC 3. Test methods and acceptance criteria shall be as given in [3.2.1].

4.2.2 Tensile and Charpy V-notch testing4.2.2.1 Test specimens shall be taken in both longitudinal and transverse direction, if geometry permits. For circular forgings such as rings and discs, longitudinal and tangential tests shall be used.

4.2.2.2 Test specimen positions shall be as given in Table 4-1. The distance from any second surface shall be as given in [3.3.3]. Test methods, Charpy V-notch (CVN) test temperature and acceptance criteria shall be as given in [3.3].

4.2.2.3 In the event that acceptance criteria are not met at ½ T position for the thickest section, engineering analysis may be performed to determine if properties are fit for use.

Table 4-1 Position of tensile and CVN specimens for qualification testing

Prolongation (if used) and sacrificial part, critical section 1) 4) Sacrificial part, thickest section 2) 3) 4)

T ≤ 100 mm (4 in.): ½ TT > 100 mm (4 in.): ¼ T, ½ T, and ¾ T

Near outer surface but not deeper than 31.75 mm (1¼ in.),At ¼ Tth, ½ Tth, and ¾ Tth, Near inner or opposite surface but not deeper than 31.75 mm (1¼ in.)

1) Thickness (T) is the thickness of the critical section at the time of heat treatment.2) Thickness (Tth) is the thickness of the thickest section at the time of heat treatment.3) Testing near outer and inner surfaces is not required for Tth ≤ 100 mm.4) Sampling of solid forgings when centre will be subsequently removed shall be at IDfinish instead of the ½ T and ½ Tth positions.


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4.2.3 Hardness testing
4.2.3.1 Testing on surfaceHardness testing shall be performed on the surfaces of the prolongation and the thickest section of the sacrificial part as follows:

— For round cross sections, at least three indentations evenly distributed along the circumference.

— For square and rectangle cross sections, at least two indentations on each side.

Forgings having a heat treated length (exclusive of prolongation) exceeding 5 m shall be tested at each end.

Test methods and acceptance criteria shall be as given in [3.3.6].

4.2.3.2 Testing through cross sectionHardness testing using stationary equipment shall be performed through the cross sections of the prolongation (if used) and the thickest section of the sacrificial part. Each cross section shall be tested along two perpendicular traverses (solid sections) or two traverses 180° apart (hollow sections). At least five indentations shall be made along each traverse at the following positions:

a) near the outer surface but not deeper than 31.75 mm (1¼ in.)

b) at ¼ T, ½ T, and ¾ T (prolongation)

c) at ¼ Tth, ½ Tth, and ¾ Tth (thickest section)

d) near the inner or opposite surface but not deeper than 31.75 mm (1¼ in.).

Test methods and acceptance criteria shall be as given in [3.3.6]. In the event that acceptance criteria are not met at ½ Tth position for the thickest section, engineering analysis may be performed to determine if properties are fit for use.

4.2.4 Testing after simulated post weld heat treatmentTensile, CVN and surface hardness testing shall be performed after SPWHT as given in [3.3.8], if applicable.

4.2.5 Metallographic examination4.2.5.1 Prior austenite grain sizeThe prior austenite grain size shall be determined on the prolongation and the thickest section of the sacrificial part. Sampling position shall be as given in Table 4-2. Test method and acceptance criteria shall be as given in [3.4].

A photo-micrograph illustrating the typical appearance of the grain structure shall be provided at a magnification of 100X or higher.

4.2.5.2 Steel cleanlinessSteel cleanliness shall be determined on the prolongation and the thickest section of the sacrificial part. Sampling position shall be as given in Table 4-2. Test method shall be as given in [3.4]. Acceptance criteria shall be as given in [3.4] for SFC 3 and in API 20B for SFC 2.

Table 4-2 Position of metallographic examination for qualification testing

Type of test Prolongation 1) Sacrificial part, thickest section 2)

Prior austenite grain size T ≤ 100 mm (4 in.): ½ TT > 100 mm (4 in.): ¼ T

¼ Tth

Steel cleanliness T ≤ 100 mm (4 in.): Close to surface and ½ TT > 100 mm (4 in.): Close to surface and ¼ T

Close to surface and ¼ Tth

1) Thickness (T) is the thickness of the critical section at the time of heat treatment.2) Thickness (Tth) is the thickness of the thickest section at the time of heat treatment.


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4.2.5.3 Wrought structure
One full section sample from the prolongation and one full section sample from the thickest section shall be taken and macro-etched according to ASTM A604 or ASTM E381.

The samples shall show a wrought structure, as defined in API 20B, throughout the section. No injurious segregation or porosity shall be permissible. Acceptance criteria shall be S1R1C1 as per ASTM E381, see ASTM Adjuncts: Photographs for Rating Macroetched Steel (3 plates). Photo-macrographs shall be taken.

4.2.6 Fracture toughness testing4.2.6.1 CTOD fracture toughness testing is required for SFC 3. Testing shall be performed according to ASTM E1820 or ISO 12135.

4.2.6.2 Unless otherwise agreed with or required by the purchaser, at least three single-edge bend specimens of width 25 mm (1 in.) shall be tested. Specimens shall be sampled from the sacrificial part at the critical section, as specified by the purchaser. Crack plane orientation shall be L-R (round section) or L-T (square/rectangular section).

Guidance note:The number, type, size and location of test specimens should also be agreed between the purchaser and the end user.

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4.2.6.3 Test temperature and acceptance criteria shall be as given in Table 4-3.

4.2.7 Non-destructive testingThe qualification forging shall be non-destructive tested (NDT) as given in [3.5].

4.2.8 Dimensional inspectionThe qualification forging shall be inspected for dimensions as given in [3.6].

4.3 ValidityFor the MPQ to remain valid, all production shall be within the limits of essential variables defined in Table 4-4. Any change outside the limits of essential variables shall lead to re-qualification.

Table 4-3 CTOD requirements at the critical section

Specified minimum yield strength (SMYS) Test temperature CTOD 1)

Up to 517 MPa (75 ksi) MDT 0.25 mmOver 517 MPa (75 ksi)Up to 586 MPa (85 ksi) MDT 0.30 mm

Over 586 MPa (85 ksi)Up to 655 MPa (95 ksi) MDT 0.35 mm

1) Values are applicable for final machined critical section thickness up to 100 mm (4 in).

Table 4-4 Validity of MPQ, limits of changes to essential variables

Essential variable Change requiring requalification SFC 2 SFC 31) Steel grade a) Change outside specified limits for chemical composition

X Xb) Increase in specified mechanical properties

2) Chemical composition a) Reduction in CE (IIW) value for CS and LAS below 0.03 of qualified CE value (based on heat analysis) X X

3) Melting, refining and casting a) Change of methods and practices for primary melting, secondary refining and casting X X

4) Forging method a) Change from open die to closed die forging or vice versaX Xb) Change from open die to ring rolling or vice versa

c) Change from press forging to hammer forging5) Forging capacity a) Reduction in forging capacity (forging press tonnage) X X6) Forging reduction ratio a) Reduction in overall forging reduction ratio X X


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7) Heat treatment a) Change of quality heat treatment parameters outside specified limits, e.g. temperature and minimum soaking time

X X

b) Increase in maximum transfer time, if more than 90 secondsc) Change of furnace typed) Increase in furnace sizee) Change of quenching mediumf) Reduction in stacking distance (stacking not permitted for SFC 3)g) Use of a subcontractor for quality heat treatment or change in

subcontractor used8) Thickness a) Increase in thickness of the critical section

X Xb) Increase in thickness of the thickest section

9) Manufacturer of starting material

a) Change of manufacturer - X

10) Ingot/bloom a) Change of ingot type- X

b) Change of methods and practices for ingot discard11) Forging weight, as heat treated

a) Increase in weight of a single forging above 10% for forgings over 2300 kg and above 25% for forgings under 2300 kg - X

Table 4-4 Validity of MPQ, limits of changes to essential variables (Continued)

Essential variable Change requiring requalification SFC 2 SFC 3


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