Steam Tracing Specification Guide

SPECIFICATION GUIDEFOR STEAM TRACING APPLICATIONS

THERMON The Heat Tracing Specialists®

1.0 General Provisions ................................................................ 2-4 1.1 Scope 1.2 Purpose 1.3 References 1.4 Steam Tracing Symbols and Legend 1.5 Codes and Standards 1.6 SpecificationAddenda 1.7 ConflictofDocuments 1.8 Contractual Relationships 1.9 Contract Words 1.10DefinitionofPlantPiping,InstrumentationandSteamTracingTerms2.0 Where to Use Steam Tracing ................................................... 53.0 Selection of Steam Pressure ................................................... 64.0 Tracing System Temperature Control Options ...................... 65.0 Tracing Methods and Design Considerations .................... 6-7 5.1 Tracing Methods 5.2 DesignConsiderations 5.3 Heat Losses Through Thermal Insulation6.0 Tracer Selection Considerations .......................................... 7-87.0 Size and Number of Tracers ................................................. 8-98.0 Tracer Materials ................................................................... 9-10 8.1 Tracer Tube Cutting and Shaping 8.2 Tracer Tube Unions 9.0 Steam Supply and Condensate Trap Stations ................ 10-11 9.1 Tracer Circuit Supply System 9.2 Trap and Condensate Return Systems 9.3 Identification 9.4 Steam Trap Selection and Installation10.0 Tracer Location and Routing .......................................... 11-12 10.1 Tracer Length11.0 Tracers for Valves and Pumps ............................................. 1212.0 Tracers on Vessels ............................................................... 1213.0 Instrument Tracing ............................................................... 1214.0 Heating Systems for Instrument Enclosures ................ 12-1315.0 Process Piping and Supports ............................................. 1316.0 Installation of Tracing System ....................................... 13-15 16.1 Surface Preparation of Process Pipe and Equipment 16.2 Surface Preparation of Tracers 16.3 Tracer Securement to Process Lines 16.4 Pressure Testing and Cleaning 16.5 Selection and Application of Heat Transfer Compounds 16.6 Insulation Selection/Application for Steam-Traced Piping/Equipment 16.7 Selection and Application of Weather Barriers17.0 Inspection of System ........................................................... 15 SpecificationSupplements:Pipingdrawings,productspecifications,materialsestimatingandmanufac-turer’sinstallationproceduresmakeupapartofbutarenotfoundwiththisspecification.

Specification Guide For Steam Tracing Applications

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1.0 General Provisions1.1Scope:Thisspecificationcoversbasicrequirementsforthedesign,materials,installation,inspectionandtest-ingofsteamtracingsystemsforplantpiping,equipmentand instruments.

1.2Purpose:Toensurethecontinuityofplantoperation,certainprocess,serviceandutilitypipes,equipmentandinstrumentswillrequiresteamtracingtokeepcontentsoffluidssuchasliquids,gases,vapors,suspensionsandslurriesfromfreezing,condensing,crystallizing,separat-ingorbecomingtooviscoustopump.

1.3References:Oneormoreofthefollowingdrawingsandmanufacturers’informationwillsupplementthisspecification: a) Piping and instrument diagrams. b) Pipingorthographicdrawings. c) Piping isometrics. d) Piping line index. e) Productspecifications,materialsestimatingandin-

stallation procedures for steam tracing materials. f) Thermalinsulationspecifications.

1.4SteamTracingSymbolsandLegend:Steam tracing willbeindicatedonthepipingandinstrumentdiagramsandthepipingisometrics.Linestobeheatedwillbeshownbyadashedlineparalleltothepipelineandtheappropriatelegendafterthelinenumbersuchas: a) BTorBTSforsteamtracingwithabare(convec-

tion)traceroratracerwithasafetyyellowidentifica-tionjacket(ThermonIndustries,Inc.,SafeTrace™BTS).

b) ITforsteamtracingwhichisisolatedfromthepro-cess pipe by a factory-applied heat retarding mate-rialfortracingtemperature-sensitivematerialsorforenergyconservation(Thermon’sSafeTrace™SLS-ITorDLS-IT).

c) HTCforsteamtracingwithheattransfercom-pounds(Thermon’srangeofheattransfermateri-als).

Allspecialconditions,includingheat-sensitivematerials,linedorspeciallycoatedpipeorothersuchconditions,willbeidentifiedonthedrawingsandschedules.

NOTE: Throughoutthisspecificationallreferencestosteam-traced piping is meant to imply all steam-traced piping,fittings,valves,pumps,tanks,vessels,instru-ments,instrumentlinesandanyothermaterialsorequipment requiring steam tracers.

Allheattransfercompoundsarenotthesame,justasall thermal insulation materials are not the same. It is importanttocheckthetechnicalspecificationsandproofofconductancetestingbyfollowingguidelinessuchasThermon’s“EvaluationofSteamTracerConductance”procedure.

1.5CodesandStandards:Allworkshallcomplywithapplicablefederal,stateandlocalcodesandindustrystandards. Since issuance of standards is an ongoing process,theEngineerwillidentifytheissuancedatetowhichthesteamtracingprojectiscommitted.

Safety precautions shall conform to the applicable requirements of Occupational Safety and Health Stan-dards,29CFR1926.

Unlessotherwiseindicated,thelatesteditionsandrevi-sionsofthefollowingdocumentsarereferredtointhisspecificationandshallbeusedtosupplementandde-finetheintentionsandrequirementsofthisspecificationwhereapplicable.ForinstallationsoutsidetheU.S.A.,allworkshallapplytocorrespondingdocumentsorotherapplicable codes and standards. • American National Standards Institute (ANSI)

B31.1 ChemicalPlantandPetroleumRefineryPip-ing Z535.1 Safety Color Code

• American Society of Mechanical Engineers (ASME)A13.1 SchemefortheIdentificationofPip-ing Systems

• American Society for Testing and Materials (ASTM)

A213 SpecificationsforSeamlessFerriticand AusteniticAlloy-SteelBoiler,Superheater,and Heat Exchanger Tubes

A269 SpecificationforSeamlessandWelded Austenitic Stainless Steel Tubing for General Ser-vice

B68 SpecificationforSeamlessCopperTube,Bright Annealed

B75 SpecificationforSeamlessCopperTube VOLUME 0.4.06 ThermalInsulation;Environmental

Acoustics(AnnualBookofStandards) • Manufacturers’ Standardization Society (MSS) MSS-SP-58 Pipe Hangers and Supports; Materials

DesignandManufacturers • American Petroleum Institute (API) 550 Part 1 - Process Instrumentation and Control

Section8-Seals,PurgesandWinterizing

Specification GuideFor Steam Tracing Applications

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1.6SpecificationAddenda:Corrections,additionsordeletionswillbeaccomplishedbyissuingaddendatothisspecification.Anyaddendumwillbeintheformofaletterormoreformaldocumentswheredeemedneces-sarybytheEngineerto:

a) AnswerquestionsraisedbybiddingContractors. b) EffectchangesmadebytheOwnerortheEngineer. c) Correcterrorsanddiscrepanciesbetweendocu-

ments.

ContractorshallsubmitdrawingsanddescriptionsforOwnerorEngineerapprovalofallitemswhichdeviatefromthisspecification.

Wherereferenceismadetoamanufacturer’sproduct,equivlentalternatesmaybeusedafterreceiptofwrittenapprovalfromOwnerorEngineer.

1.7ConflictofDocuments:Incaseofconflictbetweenthisspecificationandothercontractdocuments,theContractorshall,regardlessoftheorderofprecedenceofdocuments,contacttheEngineerinwritingbeforeproceedingwiththeaffectedwork.TheContractorshallonlyproceedafterhavingreceivedawrittenanswerfromtheEngineerthattheworkmayproceed.

1.8ContractualRelationships:

a) Manufacturer/Client:Ownerforwhomthefacilityisbeing constructed.

b) Engineer:Engineeringfirmundertakingthedesignand/or construction of the Client’s facility.

c) Purchaser:ClientortheEngineer. d) Contractor:Companywhosetenderhasbeenac-

cepted by the Purchaser.

1.9ContractWords:Thesecontractwordsshouldbeparticularlynoted:

a) Theword“shall”isusedinconnectionwithactsoftheContractororwithlabor,materialsandequip-ment furnished by the Contractor.

b) Theword“will”isusedinconnectionwithactsoftheOwnerorEngineerbutalsoappliestotheContrac-torwheresteamtracingisprovidedasa“turnkey”(design,supplyandinstall)package.

c) Theword“should”isusedonlyinconnectionwithrecommended practices.

1.10DefinitionofPlantPiping,InstrumentationandSteamTracingTerms:

• Air Convection Tracing: Tracers attached to the pipewithouttheuseofheattransfercompounds.

Tubingcanbebareormayhaveapolymerjacket.Tracerisattachedtothepipewithhightemperaturetapeandheattransferisbymeansofairconvectionmovementofheatintheannularspacebetweenthethermal insulation and the heated pipe.

• Ambient Temperature: The temperature of the air in the surrounding atmosphere. • Condensate: Waterthatisformedinthesteamtracertubewhenlatentheatisgivenupbythesteamtotheheatedpipe or equipment. Condensate is usually returned totheboilerfortheconversionbackintosteam.

• Condensate Header: The principal line for collect-ing and routing condensate from steam users to a receiver(ortoasewerwhenallowed)tobepumpedto the boiler plant to reduce the reheat requirement. Itmaybeasinglelineorhaveseveralbranches.

• Conduction Tracing: Tracer tube thermally bonded to the heated pipe or equipment by heat transfer compoundwhereprimaryheattransfermeansisbyconductiondirectlyintothemetalwallofthepipeorequipment being heated.

• Dry Steam: Steam containing no moisture. It may be either saturated or superheated.

• Heat Loss: Therateatwhichheatflowsfromahotsurface such as a process pipe to a cooler atmo-sphere,usuallystatedinBtu/h•ft.(W/m)ofpipe.Generally,theheatlossisfromthepipethroughthepipe insulation to the cooler atmosphere.

• Heat Sink: Asurfaceormasssuchasaflangeorvalvethatisatalowertemperaturethanthewarmpipe.

• Heat Tracing: Theapplicationofhotliquid,vaporor steam tracing tubes or electric heating cables or tapestopipes,fittings,valves,pumps,tanks,instru-ments or instrument lines to offset the heat loss through thermal insulation.

• Heat Transfer Compound: Aheatconductivema-terialwithhighlyefficientthermalcharacteristicsforuseonanysteamorfluidtracertube.

• Heated Pipe: Anyprocess,serviceorutilitypipethat is heat traced.

• Heating Media: Steam,hotwater,glycol,hotoilsorotherheattransferfluidsthatflowthroughtracertube circuits.

• Heat-Up: Asteamtracingapplicationwherepro-cess pipe or equipment requires the addition of heat toraiseitstemperaturefromalowertoahigherlevel.

• High Pressure Steam: Steam at a pressure of 250-600psig(17.2-41.4barg).

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• Instruments:Devicesusedseparatelyorincombi-nationtomeasure,analyzeormonitorthevariousaspects of a process.

• Instruments Piping: Allpiping,tubingortubingbundles,valvesandfittingsusedtoconnectinstru-ments to process piping and to other instruments andapparatusformeasuring,analyzingormonitor-ing purposes.

• Isolated Tracing: Tracingforenergyconservationorforsensitivepipingandprocesseswherethetracer tube is separated from the pipe or equip-mentbyalowconductivematerial.Heattransferisprimarilybyairconvectionmovementofheatintheannularspacebetweenthethermalinsulationandthe heated pipe.

• Low Pressure Steam: Steam at a pressure of 10-50psig(.7-3.4barg).

• Medium Pressure Steam: Steam at a pressure of 50-250psig(3.4-17.2barg).

• Pockets: Bends,loopsordipsinthetracertubewherecondensatecancollect.

• Process Maintenance Temperature: The tem-peraturelevelwhichmustbeheldonplantprocesspipes and equipment to keep the contents from so-lidifying,condensing,crystallizing,separatingorbe-comingtooviscoustopump.Thetermisoftenusedtorefertoalltracedutility,serviceorprocesspipes.

• Process Piping: Pipingusedtotransportfluidsbe-tweenstoragetanksandprocessunits.

• Saturated Steam: Steam of a temperature corre-sponding to its pressure.

• Service Piping: Pipingusedtotransportwater,brine,steam,airorothersubstancestoprocesspiping or equipment to bring about the successful completion of the process.

• Steam and Condensate Manifolds: Modular pre-fabricated steam supply and condensate collection unitsdesignedspecificallyforsteamtracingcircuits.

• Steam and Condensate Return Leads: Preinsu-latedtubingwithaweather-protectivejacketusedto interconnect headers to manifolds and manifolds to tracers for steam supply and condensate return. Referredtoasleads,runs,linesandtakeoffs.

• Steam Boiler: Aclosedvesselinwhichwaterisvaporizedintosteamtoprovidemechanicalpowerand process heat such as steam for tracing circuits.

• Steam Header: The principal steam line supplying steam to all users in an area including tracer cir-cuits.Assumedtobesupportedonoverheadpipe

rackandmayhaveseveralbranches. • Steam Tracing: A tube or small pipe carrying

steam,whichisplacedparallelandattachedtothesurface of the pipe or equipment to be heated. The tubeisreferredtoasthe“tracer,”“tracertube,”orsimply“tracing.”

• Steam Tracing Condensate Subheader: A line whichcollectsandreturnscondensatefromoneormoretracercircuitsviaacondensatecollectionmanifold to the condensate header.

• Steam Tracing Subheader: A branch from the steam header to the steam distribution manifold for tracer circuits.

• Steam Trap: Automaticdeviceusedtoholdsteaminasteamtracingcircuituntilithasgivenupitsla-tentheatandallowscondensate,airandothergas-estopasswhilepreventingthepassageofsteam.

• Steam-Out: A process of cleaning out the residue in a pipe by passing steam through it. It is neces-sarytoselectatracerthatcanwithstandexposureto the steamout temperature.

• Superheated Steam: Steamhavingatemperaturehigher than that corresponding to its pressure.

• Temperature Controllers: Automaticdevicesusedtocontrolsteampressureand/orflowtomaintainpipe temperature for freeze protection or process temperature control.

• Thermal Insulation: Forsteamtracingpurposes,itreferstomaterialsusedtoretardtheflowofheatfrom pipes and equipment to the surrounding atmo-sphere.

• Utilities Piping: Piping that transports the primary plantcommoditiessuchasfuelgases,fueloil,wa-ter,air,steamandcondensate.

• Vessel: Theterm“vessel”inthisspecificationreferstoanylargesurfacesuchastanks,towers,drums,reactors or exchangers.

• Weather Barrier: Aprotectivematerialcoveringtheoutersurfaceofthermalinsulationtorepelrain,snow,sleet,hosewashdownoranyothersubstancethatmightnegativelyaffectthethermalinsulation.

• Wet Steam: Steam containing moisture. • Winterization: Sometimes referred to as “freeze

protection”or“warmingservices,”winterizationisthe preparation of piping and equipment for opera-tioninwinterweather,includingcoldtemperatures,highwinds,snowandice.


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2.0 Where to Use Steam TracingSteamtracingshouldbeusedwhenitisthepracticalchoicefortheplantorspecificunitsoftheplantandwhenitispossibleforthecontentsofthepipes,equip-mentorinstrumentstofreeze,condense,crystallize,separateorbecometooviscoustopumpunderlocaltemperature conditions. Some guidelines are listed below.

PipesandEquipmentThatRequireHeating: a) Ingeneral,processlinesthatflowcontinuouslydur-

ing normal plant operation need not be traced if it is practical to drain the line or displace the material in thelinewithalowpour-pointliquid,airorgaswhentheplantisshutdown.

b) Intermittentflowlines(andlineswhereitisnotprac-ticaltodrainordisplacetheprocessfluidonshut-down)shouldbetracedifthepourpointofthefluidis higher than the minimum ambient temperature that is likely to be experienced for a period of time whichwillcausethefluidtosetupinaninsulatedlinewithouttracing.

c) Insulationalonecannotpreventfreezingoflineswhichhandlewaterorotheraqueoussolutionsinanonflowconditionifambienttemperatureremainsbelowfreezingforanextendedperiodoftime.Insu-lation can only prolong the time required to freeze andcanpreventfreezingonlyifthewaterflowismaintainedatasufficientrate.

d) Pumps and their suction lines should be traced if thefluidviscositycanbecomehighenoughtogreat-lyoverloadordamagethepumpsunlessitismorepracticaltoprovideforcirculationduringintermittentoperation or for drainage or displacement of the processfluidduringshutdowns.

e) Typicalfluidsthathavepourpointsabove32°F(0°C)andrequire“processmaintain”heatregard-lessoflocalambienttemperaturesinclude:acrylicacid,asphalt,certainconcentrationsofcausticsoda,DMT,naphthalene,No.6fueloil,para-xylene,phthalicanhydride,maleicanhydride,viscousoils,styrene,sulfur,tar,phenol,paraffin,urea,polypro-pylene,neopentylglycol,ammoniumnitrateandothers.

f) Fluidsthatmustbe“winterized”include:water,hydrocarbonscontainingwaterandotheraqueoussolutions. Facilities frequently consider all process fluidstreamstobewater-bearingandprocessgasstreamstobewater-saturated.

g) Temperature-sensitivesubstancesthatmustbekept

“warm”butmustnotbeoverheatedinclude:acids,amines,caustics,phenolicwater,glycerinandoth-ers.

h) Inadditiontomainprocessserviceandutilitylinesthatrequireheattracing,otherconsiderationsfor“winterization”mustinclude:airlines,coolingtow-ers,pumpsandassociatedpiping,knockoutpotsinsuctionlinesofgascompressors,water“draw-off”sectionsofvessels,thebottomofairorgasreceiv-erswherewatercancollect,andsafetyandreliefvalvesthatcanbecomerestrictedbyviscous,waxyor freezing material.

InstrumentsandConnectingLinesThatRequireHeating: i) Instruments used to measure and control process

gasorfluidstreamsthathavepourpoints32°F(0°C)andbelow.Thesestreamsnotonlyincludewater,theycanincludegases,lighthydrocarbonsanddistillatesthat,whenwet,formhydratesandsolidifywhensubjectedtofreezingtemperatures.These applications can be referred to as “freeze protection,”“winterization,”or“warmingservices.”

j) Instruments used to measure and control process gasorfluidstreamsthathavepourpointsabove32°F(0°C).Thesestreamsmaycontainheavyre-siduals,pitchorprocesschemicalssuchasphenolthat solidify at ambient temperatures higher than 32°F(0°C).Theseinstallationsmustbeheatedabovetheirpourpointtoensurefree-flow.

k) Instruments and piping systems that need “custom tailored”protectionforproperoperation.Processstream analyzer and emissions analyzer sample systems fall into this category.

l) Instrumentsthathavespecifictemperaturelimi-tations imposed by the manufacturer to ensure accurate and reliable operation. Analyzers and recorders fall into this category. These are delicate instrumentsthatdonotholdupwellintheextremewinter/summerambientconditions.

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3.0 Selection of Steam PressureThe heating media should be dry saturated steam. The pressure of the steam is generally contingent upon the heat input requirements of the process piping and equipmentandthepressureavailabilityatthetracerlocation.Thelowercostoflowpressuresteamshouldbebalanced against additional design considerations. The followingpointsshouldbeconsidered: a) Lowpressuresteamoffersthemaximumamount

oflatentheatperpound,andtheproblemsofflashsteamfromthecondensatearereduced.However,the pressure at the trap must be high enough to get thecondensateintothecollectionsystem,includingsufficientlifttogetintoelevatedpipewayswherenecessary. Circuit lengths for trapping increase as steam pressure increases.

b) Lowpressuresteamsystemsaremoresusceptibletofreezingwhereambienttemperaturesfallbelow-20°F(-28.9°C).Wherelowpressuresteamisused,steam traps should be freeze resistant and conden-sate lines should be properly protected.

c) Forambienttemperaturesbelow-20°F(-28.9°C),lowpressuresteam(below50psig,3.4barg)shouldbeusedonlywhereonetracerwithheattransfercompoundwillsufficetokeepprocesstemperaturesrelativelyconstantduringambienttemperatureswingsandwheretotalcircuitpressurelossescanbekeptat10%orlower.

d) Lowpressuresteammayberequiredinsomecas-estoprovideforlinescarryingtemperature-sensi-tivematerials.Isolatedtracersshouldbeconsideredforthisservice.

4.0 Tracing System Temperature Control OptionsSteamtracingeconomicscanbegreatlyimprovediftemperature control options are considered. The use of large safety design margins and the tendency to keep thetracingsystem“live”whenthereisnoheatrequire-mentshouldbeavoidedwherepossible.Propertem-perature control based on an assessment of the actual systemneedsshouldbeprovidedwhereeconomicallypractical.Controloptionsare: a) Isolatedtracerswhichprovidealowconductiveheat

pathtoreducetemperaturesandconserveenergy. b) Whereprocesstemperaturesabovewinterprotec-

tionmustbeheld,useself-actingcontrolvalveswithsensors directly measuring the temperatures of the

productorpipewall. c) Forwinterization,useself-actingcontrolvalveswith

sensors responding to the ambient air temperature. d) Fixed-temperature discharge steam traps or bal-

ancedpressuretrapswhichrespondtocondensatetemperaturecanbeusedtoallowcondensatetosubcoolwithinthetracerbeforebeingdischarged.This enables use of some of the sensible heat in the condensateandreduces,orinsomecaseselimi-nates,thereleaseofflashsteam.

e) To keep theprocessfluidtemperatureconstantduring summerorwinterenvironments,toprovideprocess heat-up after a planned or emergency shut-downwithoutovershootingthemaintaintempera-ture,orforambienttemperature-sensingcontrol,athermostaticallycontrolledsolenoidvalvecanpro-videoff-onoperation.Thethermostatservesonlypilotduty,andoff-oncontrolprovidesthetracercir-cuitwiththefullbenefitoftheheating media during start-up.

f) Inmanycases,controlcanbeachievedbypressurereducingvalveswhichvarythesteampressure.

g) Self-actingtemperaturecontrollers,fixeddischargeor balanced pressure traps and pressure reducing valvesaremanufacturedbyArmstrong,SpiraxSar-co and others. Thermostatically operated solenoid valvecontrollersareprovidedbyThermon.

NOTE: Where controllers are used for tracing cir-cuits,thesteamtrapsmustbeofadesignthatcon-tinuously drains condensate from the circuit in order topreventwaterhammer.

5.0 Tracing Methods and Design Considerations5.1TracingMethods: a) Convectiontracing,either“bare”orpolymerjack-

eted(Thermon’sSafeTrace™BTSorEngineer-approvedequal).

b) Tracingwithheattransfercompound(ThermonheattransfercompoundsorEngineer-approvedequal).

c) Isolatedtracing(Thermon’sSafeTrace™SLS-IT,DLS-ITorEngineer-approvedequal).

d) Traced preinsulated instrument tubing bundles and instrumentenclosuresasprovidedbyCellexManu-facturing,Inc.,orEngineer-approvedequal.

e) Tracingwithtemperaturecontrollers.


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5.2DesignConsiderations:Steam tracing is used primarilytomaintainaspecifiedtemperaturerangeinplant piping and equipment by determining the heat loss throughthespecifiedthicknessofinsulationandreplac-ingthatheatlosswithasteamtracer.Acompletesteamtracingsystemincorporatesallsteamsupplylines,steamtracers,heatedpipesandequipment,insulation,steamcontrolvalves,fittingsandsteamtraps.Thesys-temdesigninvolvessixfactors:threefactorsaregivenandthreearevariable.Thevariablefactorsmustbebal-anced to establish an appropriate design.

Given Variable(1)Nominalpipesize (4)Tracertype,sizeandnumber(2)Desiredpipetemp. (5)Steaminlettemperature(3)Lowambienttemp. (6)Insulationtypeandthickness

Thefollowingprocessdesignscenarioswillbeconsid-ered before selecting the tracing method to be employed foreachplantline: a) Whatwillbetheconsequencesofanunplanned

processshutdownduringtheworst-caseambientconditions?

b) Whatareprocesscontrolnormal,upperandlowertemperature restrictions?

c) Will the tracing system be required to heat up the pipeorequipmentwhenthecontentshavebecometooviscoustopumporareinasolidifiedstate?Ifso,whatistheacceptableheat-uptime?

5.3HeatLossesThroughThermalInsulation: a) Todetermineactualheatlossesforagivenset

ofconditions,acompleteinsulationspecification,includingthethermalconductivityatseveralmeantemperatures,willbeprovided.

b) Allphysicalandthermalpropertiesofthespecifiedinsulantwillbeavailablealongwithinformationre-gardingtheweatherbarriermasticorjacket.

c) Forcompositeinsulationsystems,conductivitywillbetheaverageforthetwoinsulants.

d) Softinsulants(mineralfiber,fiberglass,etc.)ofthenextlargestpipe-sizeinsulationthatwillaccommo-date the pipe and the tracer should be selected.

e) Rigidinsulation(calciumsilicate,expandedPerlite,cellularglass,etc.)maybeactualprocesspipesize,thusrequiringboardsectionscuttofitthelongitudejointtocompensateforthesteamtracer.Preferably,thenextlargestpipe-sizeinsulationthatwillac-

commodate the pipe and tracer should be selected. Rigidabrasiveinsulantsmayhaveaninnerlinerofmineralorfibrous-typeinsulation,whichmayalsobe considered in heat loss calculations.

f) Heatlosseswillbecalculatedusingtheactualinsu-lationsizeselected.Itwillbespecifiediftheinsula-tionisactualsizecompressedtofitthepipeandtracerorifitis“oversized”leavinganairannulus.Theinnerinsulationsurfacecoefficientswillvarydependinguponwhetherornotthereisanairan-nulus and the size of the annular space. The actual insulationsizewillalsohaveaneffectontheouterinsulationsurfacecoefficients.

g) Actualthicknessofinsulationwillbeusedsincetheactualthicknessdoesnotalwayscorrespondtothe nominal thickness. Refer to ASTM designation C585 “Standard Recommended Practice for Inner andOuterDiametersofRigidThermalInsulationforNominalSizesofPipeandTubing.”

h) Aminimumheatlosssafetyfactorof10%willbeused.

i) Increased heat losses from miscellaneous items suchasflanges,valves,pipeshoesandsupports,plusothercomponents,willbeconsideredoncriti-calprocesslineswherethemaintaintemperaturebandisnarrow.

j) Insulatedpipesupportswillbeconsideredoncriticaltemperature maintenance lines.

6.0 Tracer Selection ConsiderationsMostplantswillrequireacombinationofthesteamtracingmethodsdiscussedinSection5.0ofthisspecifi-cation. The selection for each heated pipe and piece of equipmentwilldependupontheprocesssensitivityandthetemperaturetobemaintainedalongwiththeheatloaddemand,tracercapabilityandtheresultsofthedesign scenarios. a) Isolatedtracingisselectedinthefollowingsitua-

tions: (1)Where reduced thermal risk is important to aid in

compliancewithapplicablesafetystandards. (2)Wherebaretracerswillconsumemoreenergy

than necessary or raise the pipe temperature too high.

(3)Whereacontrolled,predictableheattransferratemustbemaintainedforenergyconservationortopreventcorrosionorotherunacceptabletemperature related conditions.

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(4)Wheresensitiveproductssuchascaustics,ac-ids,amines,resins,waterandotheraqueousfluidsrequirelowuniformheatforfreezeprotec-tion.

NOTE: Theisolatedtracerisapreinsulatedtubewithapolymerprotectivejacketthatissuperiortothetradi-tional“spacerblock”method,whichsuspendsatracertubejustabovethepipeoninsulatingblockstomaintainanairgapbetweenthetwo.Thespacerblocksaredif-ficulttokeepinpositionduringinstallationandfrequentlyslipoutfromunderthetubetracerinservicebecauseof expansion and contraction of the tracer. Preinsulated tubingmaintainsthespecifieddistancebetweenthepipeandistapedinplacewithoutinvolvingseveraltrades.

b)Convectiontracing,eitherbareorThermon’s SafeTrace™BTS,isgenerallyselectedforthefol-lowingconditions:

(1)Whereonlyoneconvectiontracerisneededtohold the required temperature*.

(2)Wherewinterizationisneededforlinescarryingsuchmaterialasair,water,gasesorothernon-corrosiveaqueoussolutions.

(3)Wherelowheatdensityandflexibilityisneces-saryforhighmaintenancevalves,pumpsandother such equipment.

(4)Forprocesslineswhereambienttemperaturefluctuationsoremergencyshutdownandheat-uprequirementswillnotnecessitatemoreheatthantheconvectiontracerwillsupply.

* Multipleconvectiontracerscannotbeeconomicallyjustifiedwhenonetracerwithheattransfercom-poundwillsufficebecauseoftheadditionalsteamsupply connections and trap assemblies required. However,aconvectiontracermaybedoubledbackwhereallowablepressuredropsarenotexceeded.

Spiraledconvectiontracersonhorizontalrunsarenot acceptable because circumferential expansion reducestheheattransfercoefficientbyincreasingtheairgapbetweenthetracerandthepipeandtheincreased number of pockets requires more fre-quent trapping.

Spiraledconvectiontracersonverticalrunsarenotrecommended because circumferential expansion reducestheheattransfercoefficientbyincreasingtheairgapbetweenthetracerandthepipe.

c)Tracerswithheattransfercompoundarechoseninthefollowingsituations:

(1)Wheremorethanoneconvectiontracerisre-quired.

(2)Inmostcaseswherejacketedpipeorequipmentis ordinarily used.

(3) Where fast heat-up is essential after an emer-gencyoraplannedshutdown.

(4)Whereamoreeventemperaturedistributionisrequired.

(5)Wherehighheatdensityandflexibilityisre-quiredatvalves,pumpsandothersuchequip-ment.

d) Preinsulated instrument tubing bundles and high density polyurethane instrument enclosures are selectedforthefollowingsituations:

(1) Where closely predicted thermal characteristics are required for pressure and differential pres-suretransmitters,processanalyzers,emissionsanalyzers and other such applications.

(2)Wherespaceislimited,pretracedandinsulatedbundlescanbeshapedtoallowlayoutviatheshortestdistancewithsimplesupportsinloca-tionswherefieldfabricatedlinesarenotpracti-cal.

(3)Wherefactory-appliedpolymerweatherprotec-tion is preferred on critical lines.

e)Temperaturecontrollersareselectedwhen: (1)Itisessentialtopreventoverheatingoftheprod-

uct. (2)Constantviscosityisrequiredforinstrumenta-

tion. (3)Energyefficiencyisakeyrequirement.

7.0 Size and Number of TracersAcomprehensivereviewofallflowdiagramswillbemade to determine the steam tracing requirements for eachline.Isometricdrawingsidentifyingsteamsupplyheaders,tracersupplymanifolds,tracerrouting,tracertrapstationsandcondensatereturnlineswillbeprovid-ed to facilitate proper installation of the tracing system. a) Where tracing is indicated for lines on the engineer-

ingflowdiagrams,allpumps,valves,fittings,vents,drains,instruments,instrumentlinesandspecialtyitemsassociatedtherewithshallalsobeheattraced.

b) Instruments and instrument lines shall be heated in high density polyurethane enclosures and preinsu-


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latedtubingbundles(CellexManufacturing,Inc.,orEngineer-approvedequal).

c) Thesizeandnumberofconvectiontracersortrac-erswithheattransfercompoundrequiredtodeliverthe necessary heat energy to the traced pipe or equipmentwillbedeterminedfrompublisheddesigntables(Thermon’sSteamTracingDesignGuide)orfromcomputerprogramsdevelopedforsteamtracingdesign(Thermon’sCompuTrace®

or other Engineer-approvedsources).

d) Whenheat-sensitiveorcorrosivefluidsaretobetraced,careshallbetakentopreventhotspotswithinthetracingsystem.Underthesecondi-tions,anisolatedtracingsystemutilizingatracerwithapredictableheattransferrate(Thermon’sSafeTraceTM

SLS-IT,DLS-ITorEngineer-approvedequal)shallbeused.Apressurereducingvalveshallbeprovidedforthisservicewherelowersteampressures are required.

8.0 Tracer MaterialsThetracerinasteamtracingsystemmustbeasflexibleas possible for the ease of installation and conformance to the shape and layout of the pipes and equipment being heated and must act as a leakproof carrier of the heatingmedia.Wheneverpossibleitisrecommendedthat tubing be used rather than pipe for tracing because the thermal expansion of the tubing is easier to constrain and the tracer can be held closer to the surface of the heatedpipeorequipmenttoprovideahigherheattrans-ferrate.Pipetracersareinflexibleandpresentdifficultiesatelbows,flanges,valves,strainers,pumpsandotherirregular surfaces. Since coils of tubing can be unrolled andeasilybent,tracersfromtubingwillrequireamini-mumnumberoffittings.

Thetracershallbeselectedtofulfillthethermalandinstallation requirements. These requirements are deter-minedbytheprocesspipematerial,temperatureoftheprocesspipeandtracer,pressureoftheheatingmediaandtheenvironment.Thetracershallbeofmetalcloseto the potential of the process pipe so as to minimize galvaniccorrosion.Recommendationsareasfollows: a) Copper tubing tracers shall be soft annealed grade

122 and meet or exceed ASTM Standards B68 and B75.

Minimumwallthicknessshallbeasfollows: 3/8”O.D.x.032”wall(10mmO.D.x1mmwall) 1/2”O.D.x.035”wall(12mmO.D.x1mmwall) 3/4”O.D.x.049”wall(20mmO.D.x1.2mmwall)

NOTE: 1/4”O.D.(6mmO.D.)tracersplugupeasilyandshouldbeusedonlywhereabsolutelynecessaryforheatingotherrelativelysmalltubesorsimilarapplica-tions.

b) Copper tubing shall be used if the saturated steam pressure or the item being traced does not exceed 400°F(204°C)andthereisnocorrosionorotherdeterrent for using copper.

c) Stainless steel tubing tracers shall be type 316 seamlesscolddrawnandfullyannealedwithamaximumRockwellhardnessofRB80andmeetorexceedASTMStandardA269.Minimumwallthick-nessshallbeasfollows:

3/8”O.D.x.032”wall(10mmO.D.x1mmwall) 1/2”O.D.x.035”wall(12mmO.D.x1mmwall) 3/4”O.D.x.049”wall(20mmO.D.x1.2mmwall) d) Stainless steel tubing shall be used if the saturated

steam pressure or the item being traced has a max-imumtemperatureabove400°F(204°C)andthereis no corrosion or other deterrent for using stainless steel.

e) Carbon steel tracers shall not be used for steam tracingcircuits.Duringshutdownperiods,thecom-bination of air and moisture on or in the tracers causes rapid rusting.

f) Since the tracer tube is a primary component of the steamtracingsystem,thetubingshallbethoroughlyinspected prior to use to see that it conforms to the specifications,isofthecorrectdiameterandthick-ness and is not out of round.

8.1TracerTubeCuttingandShaping:Tracer tube bends shallbefreeofkinks,wrinklesorflattening.Bendsshallbemadewithamechanicaltubingbender.Bendradiishould generally be from four to ten times the outside diameter of the tube. The largest functional radius shouldbeused.Atubecutterorhacksawshallbeusedtocutthetracertubes.Guideblocksshallbeusedwithhacksawcuttingtoassureasquarecut.Outsidediam-eter(O.D.)andinsidediameter(I.D.)deburringshallbeperformedusingafilefortheO.D.andadeburringtoolfortheI.D.

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8.2TracerTubeUnions:Tubing unions shall be installed intracerswherenecessarytopermitremovalofequip-mentsuchaspumps,reliefvalves,instruments,controlvalvesandstrainers.Thetubingfittingsshallbesuitableforthepressureofthesteamwhichtheycontain.Fittingsshallbecompressiontypeasmanufacturedby“Swa-gelok”orEngineer-approvedequivalent.Thefittingsshallbemadeofmaterialcompatiblewiththetracerconstructionmaterial.Tubesshallbeformedtojoinwithtruealignmenttothecenterlineofthefittingswithoutdistortion or tension.

9.0 Steam Supply and Condensate Trap StationsThesteamsupplyshouldbetakenfromasourcewhichiscontinuouslyavailableevenduringnormalshutdownperiodswherepossible.Steamshouldbedistributedatthe highest pressure and reduced to the design require-ments of the tracer system using a pressure-reducing valve.

9.1TracerCircuitSupplySystem: a) The tracing supply header shall be adequately sized

toprovidethemaximumtracerdesignloadandtrappedatitslowpointwherepracticalandlocatedas close as possible to the point of use. Refer to manufacturer’sSteamTracingDesignGuideforrecommended steam supply header sizes. If three or more tracers are to be supplied from a common header,prefabricatedmanifoldsshallbeprovided.

b) Each tracer supply line from the header shall be equippedwithanisolationvalve.Preinsulatedtub-ingwithfactory-appliedinsulationandapolymerweatherprotectivejacket(Thermon’sThermoTube®

orEngineer-approvedequal)shallbeusedforsteam supply and condensate return leads and routedasfollows:

(1)From off the top of the tracer supply header at thehighestpointpossibleflowingdownwardtothe tracer distribution manifold subheader.

(2)From the distribution manifold to the beginning of the tracer circuit.

(3)From the end of the tracer circuit to the steam trap condensate manifold assembly.

(4)From the condensate manifold to the conden-sate return header.

(5)All preinsulated lines shall be routed symmetri-callyandruntogetherwherepossibletomaintainaneatappearance.Pocketsshallbeavoidedifpossible.

c) Supply manifolds shall be strategically located along the tracing route and shall be accessible from grade,platformsorpermanentladderswithamaxi-mumlengthof16’(5m).

d) Eachmanifoldshallbefittedwithanisolationvalveandsuitablestrainer,and15%ofthetotalnumberof tracer connections shall be spares. A fraction rep-resents one spare connection.

e) Thesupplymanifoldsshallbedrainedviaatrapandprovidedwithadiffuserforsafe,quietdischargetotheatmospherewhencondensateisnotreturnedtothe boiler house.

9.2TrapandCondensateReturnSystems:

a) Steam trap condensate manifold assemblies shall beprovidedwithaninternalsiphontubeforfreezeprotection of traps that are shut off and a freeze pro-tectionvalvewhichsensescondensatetemperatureto drain the manifold if the condensate cools to a givensetpoint.

b) Steam trap manifold assemblies shall be placed in anaccessiblelocationwherepossibletosimplifymaintenance.

c) Steamtrapmanufacturers(suchasArmstrongandSpiraxSarco)providesteamdistributionandcondensatecollectionmanifoldsdesignedspecifi-cally for steam tracing applications and are the best source of information for the selection of manifolds.

9.3Identification: a) Each tracer circuit for process lines shall be identi-

fiedbycorrosion-resistantidentificationtags.Onetagshallbelocatedatthesteamsupplyvalveatthemanifoldandtheotherattheisolationvalveofthesteam trap assembly.

b) Steam tracer supply stations and condensate trap stationswillbegivenlinenumbers.Anisometricpipingerectiondrawingwillbemadeforeachsta-tion.Thesestationswillbeassignednumberswhichare to be located on the plot plan and the model to indicateunitnumber,stationnumberandwhetherthey are supply or trap stations.

c) Theidentificationtagsshallbefabricatedfrom16gauge corrosion-resistant material suitable for the environmentandattachedtothesupplyvalveandsteamtrapassemblyvalvewith16gaugecorrosion-resistantwire.

d) Identificationtagsshallbestampedwith1/2”(12mm)numbersandlettersusingtheidentificationsystem established for the project.


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9.4SteamTrapSelectionandInstallation:Effectiveremovalofcondensateandairisessentialtoachievinguniform temperatures and maximum heat transfer rates from steam tracing circuits. Trap manufacturers are the best source of information for the selection and sizing of the steam traps and should be consulted for sizing and properinstallationtechniquestoprovidetroublefreewin-ter performance. Preassembled steam trapping stations are preferred and can be supplied by the trap manufac-turers(suchasSpiraxSarcoandArmstrong).Severaltypesoftrapsareavailablefortracercircuits.Thetypeoftrapsselectedshallmeetthedesignandefficiencyrequirements of the tracing system. a) Thesteamtrapshallbeinstalledbelowthetracer

circuitwherepossibleandatacondensatemanifoldlocatedsoasnottointerferewiththeoperationandmaintenanceofequipmentorobstructaccessways.

b) Eachtracercircuitshallbetrappedindividuallyatthe tracer termination point determined from the circuitdesigninformation.Anewtracershallbeinstalled for continuing the tracing if the pipe run ex-ceeds the maximum trapping length determined in Section 10.1.

c) Isolationvalvesshallbeinstalledjustbeforeandjustafterthetraptomakeservicingeasier.

d) Ifcondensatewillbedischargedtoanoverheadreturnlineoragainstalift,aswingcheckvalveshallbe installed in the discharge line just beyond the trapatthebottomoftheliftifthetrapdoesnothaveanintegralcheckvalveorisnototherwisedesignedtopreventbackflow.Thedischargelinefromthetrap shall feed into the top of the return main.

e) Whenatrapmustdischargetoanoverheadreturnline,thepressureduetotheliftshallbeaddedtothepressureintheoverheadreturnlinetodeter-minethetotalbackpressureagainstwhichthetrapmustdischarge.Tocalculatethepressureduetolift,use0.5psiperverticalfootoflift(11.31kp/m).Thebackpressureshallnotexceedtheallowablelimitofthe selected trap.

f) Ifthetrapdoesnotincorporateastrainer,astrainerwithablow-downvalveshallbeinstalledjustaheadofthetraptokeeprust,dirtandscaleoutofthetrap.Atestteeshallbeinstalledjustdownstreamofthetraptoallowcheckingofthetrapperformance.

10.0 Tracer Location and Routing a) Tofacilitatemaintenance,tracersservingthesame

or adjacent items shall be grouped and supplied fromacommonmanifold.Similarly,thecondensateshall be returned to a common return manifold.

b) Thesteamsupplyshallstart(wherepractical)atthehighestpointofthelinestobetraced,andthetracersshallbearrangedsothatflowisgenerallydownwardavoidingpocketsasmuchaspossible.Theaccumulatedverticaltracerrise(pocketheight)infeet(.66xbargforAVTRinmeters)shallnotex-ceed 15% of the steam supply pressure.

c) Each tracer shall be continuous from the supply manifoldtothetrapwithnovents,drainsordead-endextensionsatintermediatepoints.Ingeneral,branchconnectionsshallbeavoided.Ifbranchesarerequired,eachbranchusedshallhaveitsowntrap.

d) Foreaseofinstallationandserviceability,alltracersshall be installed parallel to and against the heated pipe or equipment and shall be placed on the most accessiblesurfacelocationinregardtosupports,easeofinstallation,connectionandthermalinsula-tion. Multiple tracers shall be equally spaced around the circumference of the pipe.

e) Expansionofbare(convection)tracertubesshallbeabsorbedatelbowsandflangeswherepossible.Forlongstraightruns,a12”(.305m)diameterhori-zontalloopshallbeprovidedat60’to100’(18-30m)intervals,preferablymidwaybetweenfittings.Tracerloopsprovidedspecificallyforexpansionshouldnotcontainunions.Tracerswithheattrans-fer compound do not require expansion loops.

f) Tracerloopsaroundflangesshallbehorizontalsoastodrainonshutdown,andunionsshallbepro-videdsothattracerscanbedisconnectedatvalves,pumps,tanksorotherflange-connectedequipment.

g) Tracing shall be included on dead legs and similar heat sinks along the traced line.

h) Eachtracershallbeservedbyasingletrapattheend of the tracer circuit.

i) Slotsshallbeprovidedinthethermalinsulationtoaccommodateexpansionofthetracerwhereitjoinsandleavesthetracedline.Detailswillbeprovidedintheinsulationspecifications.

j) Extra tracer lengths are not generally required at pipehangers,pipingteesandells.

k) Designshallincludeextratracerlengthforvalvesorlargepiecesofequipment.TheEngineerwillin-dicateoncriticalserviceifpipesupportsorflangesrequire additional tracer length. Insulated pipe supportswillbeconsideredoncriticaltemperaturemaintenance situations.

l) All tracers shall be arranged such that maintenance andremovalofvalves,instrumentsandothersuchequipmentisnotadverselyaffected.

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10.1TracerLength: a) Refertomanufacturer’sSteamTracingDesign

Guide to obtain recommended circuit lengths for trapping. Longer tracer runs may be possible based ontheactualcalculatedheatlossforagivenpipeunderequilibriumconditionsandtheallowablecir-cuit pressure drop. A computer-generated design from Thermon’s CompuTrace® program or other Engineer-approvedprogramsmaybeusedforcir-cuit length optimization.

b) Tracercircuitlengthswillbecalculatedonamaxi-mumallowablepressuredropof30%ofthesteamsupplypressurebutwillgenerallybedesignedfora10% pressure drop. Maximum tracer length is mea-suredfromthepointwherethetracerfirstcontactsthelinetobeheatedtothepointwhereitconnectsto the trap or the preinsulated tubing routed to the trap.

c) Pressure losses for preinsulated tubing runs from thesteammanifoldtothetracercircuit,fromthetracertothecondensatemanifold,andfromthemanifoldtothecondensatereturnheaderwillbecalculated separately if the length of these runs ex-ceeds100’(30m)total.

11.0 Tracers for Valves and Pumps a) Tracingforvalvesandpumpsshallbetubinginthe

form of hairpin loops so that the tracer makes the least amount of complete circles. The number of feetoftracertosurfaceareaofvalveorpumpshallbesufficienttobalancethefeetoftraceronthestraight pipe surface area.

b) Unlessotherwisespecified,hairpintubingloopsshallbeattachedtothevalveorpumpsurfacewith1/2”x.020”(12mmx.5mm)stainlesssteelbands,hightemperaturefiberglasstapeorNo.16gaugestainlesssteelwire(seesupplementaltracerinstal-lationdrawings).

12.0 Tracers on Vessels a) Unlessotherwisespecified,externaltracingforves-

sels shall be stainless steel panels prefabricated totherequiredradius(Thermon’sHeetSheet® or Engineer-approvedequal).

b) Heatingpanelsshallhavealayeroffactory-appliednonhardeningheattransfercompoundbetweenthevesselsurfaceandthebackoftheheatingpanel.

c) Smallequipmentwithanoutsideradiusofcurva-turelessthan7”(178mm)andvesselbottomswith

compoundcurvedsurfacesmaybetracedwithtubing in the form of hairpin loops in lieu of heating panels.

d) Unlessotherwisespecified,hairpincircuitsshallbeembeddedinheattransfercompound(seesupple-mentaldrawingsforinstallationdetails).

e) Vesselsshallbeinsulatedwithdouble-locking,con-tinuous-standingseaminsulationpanels(Thermon’s ThermaSeamTM

orEngineer-approvedequal).

13.0 Instrument Tracing a) Tracing for instruments and instrument impulse

linesshallconformwithinformationprovidedinthesupplementaldrawings.PreinsulatedtubingshallbeCellex’s TubeTrace®

orEngineer-approvedequal. b) Tracing shall be designed such that instruments can

beremovedformaintenancewithoutinterruptionorremovingthetracing.

c) Tracingshallbeappliedonlytotheprocesswettedpartsofinstruments,nottoelectronicorpneumaticparts.

d) Tracersizesshallbeasfollows: (1)1/2”(12mm)O.D.tubingforgaugeglassand

externaldisplacerlevelinstruments. (2)1/4”(6mm),3/8”(10mm)and1/2”(12mm)

O.D.tubingformeterleads.

14.0 Heating Systems for Instrument Enclosures a) Pressuregaugeenclosuresshallbeheatedwiththe

heat from the process line by installing heat conser-vationinsulationuptotheenclosureorbycontinu-ing the tracer at the gauge connection.

b) Differentialpressuretransmitterswithpartialen-closures shall be heated by a steam heater block installedundertheinstrument.Heatershallhaveitsownflexiblethermalinsulationcoverandbein-stalledwhereitwillnotinterferewithremovalofthetransmitter.

c) Transmitters,controllers,recorders,etc.,withcom-pletepolyurethaneenclosuresshallbeheatedwithaseparatefinnedsteamheaterconnectedbytubefittingstothesteamtracer.Heatersandcontrol-lers shall be by Cellex Manufacturing Company or Engineer-approvedequal.

NOTE: Wherepossible,preinsulatedtubingbundlesshallbeusedinlieuoffieldtracedandinsulatedin-strument lead lines.


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15.0 Process Piping and Supports a) ThePipeSupportGroupwillseethatallprocess

pipingisproperlysecuredbysupports,guides,anchorsorhangersinkeepingwiththepipingspec-ifications.Tothegreatestextentpossible,anyap-pendages shall be arranged such that tracers and thermal insulation can be installed in accordance withspecifiedpractices.

b) The installation and support of preinsulated instru-ment tubing bundles and preinsulated steam supply andcondensatereturnlinesisgiveninthesupple-mentaldrawings.Generally,however,routingandsupportistobedeterminedinthefield.Linesshallbe run together as much as possible for common support. Preinsulated tubing shall be spaced and locatedwiththeseconsiderations:

(1) Ability to place a durable support at some de-sired location.

(2)Keepsaginthelinewithinlimitsthatwillpermitdrainage.

(3 Avoidbendsthatexceedtheminimumbendra-dius as recommended by the manufacturer.

(4 Allowforheatdissipationbykeepinga1/2”(12mm)space(minimum)betweenthepreinsulatedlines.

16.0 Installation of Tracing SystemAftertheprocesspipehasbeeninstalledwithpropersupportsandhangerstoallowforcorrectapplicationoftracersandinsulation,thefollowingaremajorstepsforinstallationofthetracersystem: a) Surface preparation of process piping. b) Surface preparation of tracer. c) Installation of tracer and its securement. d) Pressure testing of tracer. e) Applicationofheattransfercompound(wherere-

quired). f) Curingofheattransfercompound(ifrequired). g) Inspectionoftracersystem(see17.0). h) Application of thermal insulation. i) Applicationofweatherbarrier. j) Inspectionofinsulation(see17.0).

16.1SurfacePreparationofProcessPipeandEquipment:In caseswherethepipeislocatedinacorrosiveatmo-sphereorwherecorrosiveleaksorspillagemaypossiblyattackthepiping,thecoatingsandpaintingengineerwillspecify corrosion protection coatings that are compatible withthesteamtracingsystemrequirements.Thefollow-inggeneralguidelinesshouldbeconsidered:

a) Beforeinstallationofsteamtracers,alltracertubesand pipes or equipment to be traced shall be rea-sonablyclean.Dirt,rustandscalecanberemovedwithawirebrush.Oilandgreasefilmsmayberemovedwitharagandsuitablesolvent.Whererequired,millvarnishorothercoatingsmaybere-movedwithasuitablestripper.Preparationfortheapplicationofheattransfercompoundiscoveredinthesupplementaldrawingsandinstallationdetails.

b) Carbonsteelpipeandequipmentoperatingabove175°F(80°C)neednotbecoatedorpaintedtopre-ventrusting.

c) Carbonsteelpipeandequipmentoperatingbelow175°F(80°C)mayrequireasurfacepreparationandcoatingspecifiedbythecoatingsandpaintingengi-neer.

d) Stainless steel pipe and equipment in ordinary at-mospheresneedonlytobecleanedasspecifiedina)above.However,whereitmaybesubjectedtochlorideorfluorideions,thecorrosionengineershoulddeterminethenecessitytopaint(coat)thesurface.

e) Copper or brass pipe or equipment in ordinary at-mospheresneedonlytobecleanedasspecifiedina)above.

f) Aluminum pipe or equipment may need to be paint-ed if it is in a highly caustic or salt atmosphere. Sur-face preparation for the application of heat transfer compoundisspecifiedinthesupplementaldraw-ings and installation details.

16.2SurfacePreparationofTracers:All tracers shall befreeofdirt,grease,oil,loosescaleoranyothernonspecifiedmaterialbefore installation on piping and equipment and prior to application of heat transfer com-poundwhenapplicable.

16.3TracerSecurementtoProcessLines:It is important topreventstressinthetracertubingbyprovidingforexpansionwhererequiredandbyproperlysecuringthetracer to the process pipe. Tracers are fastened to plant pipingandequipmentwithwire,bandsandhightemper-aturetapes.Sometracersarecoveredwithgalvanizedorstainlesssteelchannelsbeforefinalattachment.Eachmethodoftracinginthisspecification(bareconvectiontracing,tracingwithheattransfercompoundandisolatedtracers)shallbeinstalledinaccordancewiththeinstalla-tioninstructionsprovidedinthesupplementaldrawings.Care shall be taken to use fastening materials that are galvanicallycompatiblewiththepipeandtracermateri-als.Hightemperaturetapesshallbevirtuallyfreeofchlorides or halides if used to secure stainless steel pipe or tubing.

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16.4PressureTestingandCleaning: a) Steam supply headers and pipe or tubing runs to

tracersshallbeblowncleanwithsteamorairbeforeconnection to trap assemblies.

b) After all tracer connections to the supply header andtraphavebeencompleted,thecircuitshallbetested for leaks by subjecting it to a steam pressure equaltoorgreaterthanthatwhichistobeusedinthe system or by suitable hydrostatic tests. All leaks shall be repaired and the system retested prior to theinstallationofheatconductingcompound(whenused) and insulation.

c) Performanceoftraps,gauges,pressurereliefvalves,andpressureand/ortemperaturecontrollingdevicesshallbeperiodicallycheckedatprescribedintervalsduringstart-upandthefirst48hoursofnormal operation.

16.5 Selection and Application of Heat Transfer Com-pounds:

Variousformulationsofheattransfercompoundsareavailabletocoverawiderangeoftracingapplications.Theselectionoftheproperformulationwillinvolvecon-siderationofallthefollowing:

a) Minimumandmaximumtemperaturestowhichheattransfercompoundswillbeexposedunderbothnor-mal and abnormal operating conditions.

b) Ambientconditionsunderwhichinstallationofheattransfer compounds must occur.

c) Pipingandequipmentsizeandconfiguration. d) Total installed cost for the heat transfer compounds. e) Feasibility of carrying out start-up curing procedures

(whererequired). f) Solubility resistance of the heat transfer com-

pounds.

Tomaketheproperselection,basiccharacteristicsofthevariousformulationsaredetailedinthesupplementaldrawingsandinstallationdetails.Heattransfercom-poundsshallbesuppliedbyanISO9001certifiedmanu-facturersuchasThermonIndustries,Inc.,orEngineer-approvedequal.

16.6 Insulation Selection and Application for Steam-TracedPipingandEquipment:

a) The insulation material to be used on steam-traced pipingandequipmentshallbeselectedwithcare.Importantaspectstobeconsideredare:

(1) Thermal insulating characteristics. (2) Mechanical strength characteristics. (3) Chemical stability characteristics under both nor-

mal and abnormal conditions. (4) Moisture absorption characteristics. (5) Personnel health and safety aspects. (6) Installed cost. b) Thefollowingthermalinsulationmaterialsandthe

corresponding ASTM Standard are commonly used forsteam-tracedpiping:

Type ASTM Standard Calcium Silicate C533 Cellular Glass C552 FiberglassandMineralWool C547,C553,C592 Expanded Perlite C610

c) Theinsulationmaterialslistedinb)aboveallhaveuppertemperaturelimitsbeyondthelevelrequiredfor steam tracing systems. For process tempera-turesbelow212°F(100°C),insulationmaterialswithalowmoisturepermeabilityshouldbeconsideredfor use. The manufacturer’s maximum and minimum temperaturelimitsshallbeadheredtowhenspeci-fying the insulation material.

d) Pipe insulation is dimensionally described by the standardpipesizethatitisdesignedtofitandbyitsnominalinsulationthickness.Forexample,a4”x1-1/2” (100mmx38mm)pipeinsulationisdesignedtofitsnuglyaroundtheactual4.5”(114.3mm)outsidediameterofthepipeandwillbenomi-nally1-1/2”(38mm)inthickness.Insomecases,the actual thickness may be as much as 25% great-erthanthenominalvalues.

e) Manufacturerspecificationsshallbeconsultedforactualdimensionaldata.ASTMC585,“StandardRecommendedPracticeforInnerandOuterDiam-eters of Rigid Thermal Insulation for Nominal Sizes ofPipeandTubing,”isanadditionaldatasource.

f) DimensionsforprefabricatedfittingscanbefoundunderASTMC450,“PrefabricationandFieldFabri-cationofThermalInsulationFittingCoversforNPSPiping.”

g) Insulationcoversforvalves,flanges,pipesupportsand other line equipment shall be fabricated from blockorcurvedsegmentsofthesamematerialand thickness used for the adjacent straight piping. Cracksandjointsshallbeappropriatelyfilledandsealed to assure uniform heat loss throughout the length of the line.


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h) Thermalinsulationsizestofitoversteamtracersareprovidedinthesupplementaldrawingsandin-stallation information.

16.7SelectionandApplicationofWeatherBarriers:The proper operation of any tracing system depends upon the insulation being dry. Properly designed and installed weatherbarriersminimizethemigrationofwaterintotheinsulationandarethereforeaverynecessarypartofaneffectiveinsulationsystem.Thetwotypesofweatherbarriers most commonly used are jacketing and mastic.

Manufacturers are the best source of information for weatherbarriers,masticsandotherinsulationacces-sories.ASTMStandardsprovideanothersourceofdata.Jacketingmaterialssuchasaluminum,ASJ,FPRandstainlesssteelarecoveredinASTMC921alongwithbandingandotheraccessories.ThevariousmasticmaterialsusedforweatherproofingmaybelocatedinASTMC647.Double-locking,continuous-standingseaminsulationpanels(Thermon’sThermaSeam™orEngi-neer-approvedequal)shallbeusedfortankinsulationandweatherprotectionrequirements.

17.0 Inspection of SystemThe Inspectors shall ensure that all phases of the instal-lationareinaccordancewiththematerialsandapplica-tionspecifications.TheInspectorshallmakecertainthat:

a) Allmaterialsusedareasspecifiedandingoodcon-dition.

b) Allmaterialsarestoredinaccordancewithrecom-mendations.

c) Surfacepreparationsareasspecified. d) Tracersystemsareinstalledinaccordancewiththe

design. e) Alltracingsupplyheaders,preinsulatedsupplyand

condensatetubingruns,tracertubesandmanifoldsare steam cleaned prior to connection to trap as-semblies.

f) All tracer circuits and process pipe runs are pres-sure tested after all connections are completed.

g) Heat transfer compounds are installed in accor-dancewiththesespecifications.

h) Heat transfer compounds are properly cured. i) Water soluble heat transfer compounds are protect-

ed from rain and other moisture prior to installing thethermalinsulationandweatherbarrier.

j) High temperature insulation is of proper thickness andinstalledinaccordancewithspecifications.

k) Insulationwasdrywheninstalledandprotectedfromrainandmoistureuntilweatherbarrierwasin-stalled.

l) Allinsulationonvesselsisproperlysupported. m) Suitable insulation expansion joints are installed. n) Weatherprotectionisoftypespecified,installedin

accordancewithspecificationsandrecommenda-tionsanddrythicknessofmasticisofspecifieddi-mension.

o) Allweatherbarriersarewatertightandprojectionsand terminations are properly sealed.

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