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PIPE RACK DESIGN GUIDELINESGotopage1,2Next
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nestlejinSEFIMember
Joined:16Jul2010Posts:19
Posted:TueAug31,20109:07amPostsubject:PIPERACKDESIGNGUIDELINES
Dearall,Givenweblinkisveryusefulltounderstandpiperackdesign
http://www.civildesignhelp.info/pr.html
PiperackDesignPhilosophy
InthispageIwilltalkaboutthepiperackdesignphilosophy.Piperackisthemainarteryofanyplant.Thiscarriesthepipesandcabletrays(raceways)fromoneequipmenttoanotherequipmentwithinaprocessunit(calledISBLpiperack)orcarriesthepipeandcabletraysfromoneunittoanotherunit(calledOSBLpiperack).SometimesyouwillalsofindtheAIRCOOLEDHEATEXCHANGERSonthepiperack.
Therearedifferenttypesofpiperack:
ContinuousPiperacks(conventionalpiperack)systemNoncontinuousPiperackssystemModularPiperack
Conventional/ContinuousPiperack
ContinuousPiperacks(conventionalpiperack)system:Thisisessentiallyasystemwheremultiple2dimensional(2D)frameassemblies(commonlycalledbents),comprisedoftwoormorecolumnswithtransversebeams,aretiedtogetherinthelongitudinaldirectionutilizingbeamstruts(forsupportoftransversepipeandracewayelementsandforlongitudinalstabilityofthesystem)andverticalbracingtoforma3Dspaceframearrangement.Piperackssupportingequipmentsuchasaircooledheatexchangersmustutilizethecontinuoussystemapproach.
Step1:Datacollectionforpiperackdesign:
Duetothefasttracknatureassociatedwithmostoftheprojects,oftenthefinalpiping,raceway,andequipmentinformationisnotavailableatinitiationofthepiperackdesign.Therefore,asaCivil/StructuralEngineer,youshouldcoordinatewiththePipinggroup,Electrical,ControlSystems,andMechanicalgroupstoobtainasmuchpreliminaryinformationaspossible.Whenreceived,alldesigninformationshouldbedocumentedforfuturereferenceandverification.Intheinitialdesign,theEngineershouldusejudgementwhenapplyingorallowingforloadsthatarenotknown,justifyingtheminthedesignbasisunder"DesignPhilosophy"(apartofyourcalculation)
Thefollowingshouldbereviewedfordesigninformation:
Plotplansandequipmentlocationplans3Dmodelshowingpipinglayout,cabletraylayout,Piperackbentspacingandelevationofsupportlevels
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08/05/2015 www.sefindia.org::ViewtopicPIPERACKDESIGNGUIDELINES
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inthetransversedirection,Elevationoflongitudinalbeamstrutsandlocationsofverticalbracing.andlocationofpipebridge,ifany.Pipingorthographicdrawings.Vendorprintsofequipmentlocatedontherack,e.g.,aircoolersandexchangers.Thevendorprintsshouldincludetheequipmentlayout,mountinglocationsanddetails,accessandmaintenancerequirements,andthemagnitudeanddirectionofloadsbeingtransmittedtothepiperack.Electricalandcontrolsystemsdrawingsshowingtheroutingandlocationofelectricalandinstrumentationracewaysand/orsupports.Undergrounddrawingsthatshowthelocationsofburiedpipes,concretestructuresandfoundations,ductbanks,etc.intheareaofthepiperack.Piperackconstructionmaterial(Steel,Castinsituconcrete,Precastconcrete)shallbeasperprojectdesigncriteria.
Pleasenotethat,Unlessspecificallyexplainedintheprojectdesigncriteria,noallowanceorprovisionsshouldbemadeforfutureadditionsforpipeorracewayspaceandrelatedloading.
Step2:Designloadsconsideration:
Followingloadsaretobeconsideredforthepiperackdesign:
PipingGravityload(D):Intheabsenceofdefinedpipingloadsandlocations,anassumedminimumuniformpipeloadof2.0kPashouldbeusedforpreliminarydesignofpiperacks.Thiscorrespondstoanequivalentloadof6in(150mm)linesfullofwatercoveredwith2in(50mm)thickinsulation,andspacedon12in(300mm)centers.ThisassumptionshouldbeverifiedbasedoncoordinationwiththePipingGroup,andconcentratedloadsshouldalsobeappliedforanyanticipatedlargepipes.Whentheactualloadsandlocationsbecomeknown,astheprojectdevelops,thestructuraldesignshouldbecheckedagainsttheseassumedinitialloadparametersandrevisedasrequired.Aconcentratedloadshouldthenbeaddedforpipesthatare12in(300mm)andlargerindiameter.TheconcentratedloadPshouldbe:
P=(Wsxpxd),s=Spacingofpiperackbent,p=pipeweightconsidered(kPa),d=pipediameterW=pipeconcentratedload.
Whereconsiderationofupliftorsystemstabilityduetowindorseismicoccurrencesisrequired,use60%ofthedesigngravityloadsasan"allpipesempty"loadcondition.
Loadingduetohydrostatictestingoflinesshouldbeconsideredinthedesignifapplicable.Coordinatethetestingplan(s)withConstruction,Startup,and/orthePipingGroupasnecessary,inordertofullyunderstandhowsuchloadswillbeappliedtothepiperackstructure.Undermostnormalconditions,multiplelineswillnotbesimultaneouslytested.Thehydrotestloadsdonotnormallyneedtobeconsideredconcurrentlywiththeothernonpermanentloads,suchasliveload,wind,earthquake,andthermal.Typicalpracticeistopermitanoverstressof15%forthehydrotestcondition.Becauseoftheseconsiderations,thehydrotestconditionwillnotnormallygovernexceptforverylargediameterpipes.ElectricalTrayandConduits(D):Electricalandcontrolsystemsdrawingsand/ortheproject3Dmodelshouldbereviewedtodeterminetheapproximateweightandlocationofelectricaltrays,conduits,andinstrumentationcommodities.Unlesstheweightoftheloadedracewayscanbedefined,anassumedminimumuniformloadof1.0kPashouldbeusedforsingletierraceways.
SelfweightofPiperack(D):Theweightofallstructuralmembers,includingfireproofing,shouldbeconsideredinthedesignofthepiperack.
WeightofEquipmentonpiperack(D):Equipmentweights,includingerection,empty,operating,andtest(iftheequipmentistobehydrotestedonthepiperack),shouldbeobtainedfromthevendordrawings.Theequipmentweightshouldincludethedeadweightofallassociatedplatforms,ladders,andwalkways,asapplicable.SpecialLoads:Specialconsiderationshouldbegiventounusualloads,suchaslargevalves,expansionloops,andunusualpipingorelectricalconfigurations.
LiveLoad(L):Liveload(L)onaccessplatformsandwalkwaysandonequipmentplatformsshouldbeconsidered,asapplicable.
SnowLoad(S):Snowloadtobeconsideredoncabletrayandonlargediapipes.Thisloadshallbecalculatedperprojectapproveddesigncodeandprojectdesigncriteria.Generally,youneedtoconsider100%snowloadontoptierand50%onothertierofpiperacks.
WindLoad(W):Transversewindloadonstructuralmembers,piping,electricaltrays,equipment,platforms,andladdersshouldbedeterminedinaccordancewithprojectapproveddesigncode.Longitudinalwindshouldtypicallybeappliedtostructuralframing,cabletrayverticaldrop(ifany),largediapipesverticaldrop(ifany)andequipmentonly.Theeffectsoflongitudinalwindonpipingandtraysrunningparalleltothewinddirectionshouldbeneglected.
08/05/2015 www.sefindia.org::ViewtopicPIPERACKDESIGNGUIDELINES
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EarthquakeLoads(E):Earthquakeloadsinthevertical,transverse,andlongitudinaldirectionsshouldbedeterminedinaccordancewiththeprojectdesigncriteria.Vertical,transverse,andlongitudinalseismicforcesgeneratedbythepipes,raceways,supportedequipment,andthepiperackstructureshouldbeconsideredandshouldbebasedontheiroperatingweights.Pipesmustbeevaluatedforseismicloadsunderbothfullandemptyconditionsandthencombinedwiththecorrespondinggravityloads.
FrictionLoading(Tf):Frictionforcescausedbyhotlinesslidingacrossthepipesupportduringstartupandshutdownareassumedtobepartiallyresistedthroughfrictionbynearbycoldlines.Therefore,inordertoprovideforanominalunbalanceoffrictionforcesactingonapipesupport,aresultantlongitudinalfrictionforceequalto7.5%ofthetotalpipeweightor30%ofanyoneormorelinesknowntoactsimultaneouslyinthesamedirection,whicheverislarger,isassumedforpiperackdesign.Frictionbetweenpipingandsupportingsteelshouldnotbereliedupontoresistwindorseismicloads.
AnchorandGuideLoads(Ta):PiperacksshouldbecheckedforanchorandguideloadsasdeterminedbythePipeStressGroup.Itmaybenecessarytousehorizontalbracingiflargeanchorforcesareencountered.Forconventionalpiperacksystems,itisnormallypreferredtoeitherhavetheanchorsstaggeredalongthepiperacksothateachsupporthasonlyoneortwoanchors,ortoanchormostpipesononebracedsupport.Forinitialdesign,whenanchorandguideloadsarenotknown,usealongitudinalanchorforceof5.0kNactingatmidspanofeachbenttransversebeam(referprojectdesigncriteria).GuideloadsareusuallysmallandmaybeignoreduntiltheyaredefinedbythePipeStressEngineer.Fornoncontinuouspiperacksystems,pipingmaybetransverselyguidedoranchoredatbothcantileverframesandanchorbays.Longitudinalanchorsmaybelocatedonlyatanchorbays.
Pleasenotethat,allfrictionforcesandanchorforceswithlessmagnitude,(say~5.0kN),appliedtothetopflangeofthebeam,maybeconsideredasresistedbythetotalbeamsection.Whenanchorloadshavelargemagnitudeandareappliedtothetopflangeofthebeam,theeffectoftorsionmustbeaddressed.Ifthebeamsectionisinadequatetotakecareofthistorsionalforce,alternativestobeconsidered,suchasprovidehorizontalbracingsattheloadlocations.
Step3:LoadCombinationsandallowabledeflectionofpiperack:
Youneedtocreatetheloadcombinationsperyourprojectdesigncriteria.However,Ihavereferedheresomeloadcombinations.
Pleasenotethefollowing:
Earthquakeloadisafactoredload.Forloadcombinationsthatincludewindorearthquakeloads,useonlythenonfrictionportion(anchorandguideportion)ofthethermalloads,i.e.,frictionloadsarenotcombinedwithwindorseismicloads.Frictionloadsareconsideredtobeselfrelievingduringwindandearthquakeandshouldonlybecombinedwithanchorandguideloadswhenwindorearthquakeloadsa
