Layout Explained _ PIPING GUIDE

6/8/2015 HowtodoPumpPipingwithLayoutExplained|PIPINGGUIDE

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HowtodoPumpPipingwithLayoutExplained

PostedbyAnkitChughon1:04PM

1.0PURPOSE

To provide the layout designer guidelines for developing pump piping designs that fully consider safety, operation,maintenanceandeconomics.

2.0EXCLUSIONS

Allorpartofthisguidemaybesupersededbyclientmandatorystandardsorbythecodesandregulationsimposedbygovernmentaljurisdictionscoveringthelocationwherethepipingisinstalled.

3.0DISCUSSION

3.1SAFETY

Properconsiderationforpersonnelsafetyaroundpumpsrequirespipingandvalvearrangementsthatdonotobstructaccess for operation, maintenance or egress. Care must be exercised not to create tripping hazards with auxiliarypiping.

3.2OPERATION

Pumpsnormallyrequireminimalattentionduringoperation.Valveshowever,mustbe locatedforeasyaccess this isparticularly true forpairedorsparedpumps.Wheremanualvalvescannotbeoperatedfromgrade,chainoperatorsshallbeused.Ifchainoperatorsarenotallowedperclientspecifications,platformaccesstovalvesshallbeconsidered.

3.3MAINTENANCE

Pipingshallbearrangedinamannertoallowadequateaccesstothepumpwithoutrequiringexcessivedismantlingofthepipingsystem.Thecouplingbetweenthepumpanditsdrivermustbeeasilyaccessedinordertoalignthepumpanddriver.Pumpsealaccessmustalsobeconsidered.Pipingmustbekeptclearfromabovethepumpforhorizontally



splitpumpcasingstoallowmaintenance.Forverticallysplitcasings,accessmustbeprovidedinfrontofthepumps.

Clearance for forkliftsormobilecranesshouldbeprovided formaintenance. Incaseswherepumpsare located inabuildingorotherareaswhereoverheadaccessislimited,monorailsorriggingbeamsshouldbeconsideredforremovalofthepumpand/ormotor.

4.0TYPESOFPUMPS

Pumps are available in many different types. The most common are centrifugal, reciprocating and rotary.Reciprocating and rotary pumps are positive displacement pumps. Centrifugal pumps will usually be one of threetypes horizontal, vertical inline or vertical can type. They may have electric motor or steam turbine drivers. (SeeFigure 1 for examples of horizontal, vertical inline and vertical can type centrifugal pumps) Reciprocating pumpsmayhaveadirectsteampistondriver.

TypesofCommonCentrifugalPumps

Rotarypumpsusuallyhaveanelectricmotordriverbutmaybesteamturbinedriven.Inmanycases,thefluidpumpedbyrotarypumpsissoviscousthatblockvalvesarenotnecessary.Inthatcase,thereliefvalvemaynotbenecessary.Ifturbinedriven,therewillbeagearboxbetweenthepumpandturbine.

5.0PUMPLOCATION

Pumplocationwillaffectthepipinglayoutandhowthepipingcanbesupported.Pumpsinflammableserviceshallbelocated outboard of overheadpiperacks or structures. Those innonflammable servicemaybe located beneath thepiperack (subject to allowance in client specifications).Pumps shall be located as close aspossible to the sourceofsuction in order tominimize pressure drop in the systemwhile satisfying piping flexibility requirements and nozzleloadallowable.Linesizeandtemperatureshouldbedeterminingfactorsinroutingthepiping.



6.0GENERALPUMPPIPING

Pump suction piping shall be arranged such that the flow is as smooth and uniform as practicable at the pumpsuction nozzle. To accomplish this, the use of tees, crosses, valves, strainers, near runsize branch connections, andshortradiuselbowsshallbeavoidednearthesuctionnozzle.Suctionpipingshallbedesignedwithouthighpointstopreventcollectionofvapors.Suctionpipingshallnotbepocketed.Whenpumpflangesareflatfaced,matingflangesmustalsobeflatfacedandthejointmadeupusingfullfacedgaskets.

Multiplepumparrangementsthatconnecttoacommondischargeheadershallhavethedischargesconnectedtotheheadersuchthatthedischargesfrompumpsoperatingsimultaneouslydonotopposeoneanother.

The suction line for all systemsdesigned toAPI recommendations that connect toAPIpumpswith end, topor sidesuctionnozzles,orAPIinlinepumps,shallhaveastraightrunoffivepipediameters(nozzlesize)betweenthesuctionflangeandthefirstelbow,tee,valve,reducerorpermanentstrainer(Figure4).ThesuctionlineforpumpsotherthanAPI,shallhaveaminimumstraightrunlengthofthreepipediameters.Thisstraightrunlengthshouldbemaximized,butinanycasethepumpmanufacturersrecommendationsshouldbefollowed(Figure5).

6.1REDUCERTYPEANDLOCATION

Eccentricreducersinhorizontalpumpsuctionlinesshallbeflatontopinordertopreventanyentrainedvaporsintheliquidfromaccumulating inthehighpointandpossiblycausingcavitation inthepump.Pumps inboiler feedwaterserviceoperatingatclosetothevaporpressureoftheliquidareparticularlysusceptibletothisproblem.

The reducer shall be concentric for overhead piping into a top suction pump. (See Figure 2) Reducers in pumpdischarge lines shall be concentric and located as close as possible to the pumpdischarge nozzle. In caseswhere acombination of nozzle size, nozzle location, pipe size and insulation thickness create flange to pipe/insulationinterference,eccentricreducersmaybeusedtogaintherequiredclearance.



Reducerslocationsatpumps

Careshouldbeexercisedwhenusingatopflatreducernexttoapumpsuctionnozzlewherethechangeindiametersexceeds4in/100mm,asthiscouldresultinadisturbedflowpatternintotheimpellerandcausevibrationandrapidwear.

6.2VALVELOCATIONANDORIENTATION

Valvehandwheelsshallbeorientedinamannerresultingingoodaccesstothevalveandpump.Thesuctionlinevalveshallbeinstalledwiththesteminthehorizontal.(i.e.installvalveintheverticalrunofpipe).Gatevalvesinstalledinthehorizontalcanaccumulatevaporinthebonnetcavityandcausecavitationinthepumpwhenthetrappedvaporbreaksloose.

6.3HORIZONTALDISCHARGEOFFSET

If existing steel is not available for support of the discharge piping, or if the check valve must be installed in ahorizontalrun,thenAlternate1inFigure3shallbeused.

TypicalPumpDischargePiping

Whendischargepipingishorizontallyoffset,caremustbeexercisednottoblockaccesstothepumpcoupling,sealsorbearings(Seefigures3&12).

6.4TEMPORARYANDPERMANENTSUCTIONSTRAINERINSTALLATION

Specialattentionmustbegiventothelocationoftemporarysuctionstrainerstoallowforremoval.Figures4&5showexamplesofsuctionstrainerinstallation.



TYPICALPIPINGFORENDSUCTIONTOPDISCHARGEPUMPS(APIPUMPSONLY)



TYPICALPIPINGFORENDSUCTIONTOPDISCHARGEPUMPS(NONAPIPUMPSONLY)

ForpermanentTtypeandYtypestrainers installed inahorizontalsuction line, thepreferredpositionof thecleanoutconnectionis30to40degreesfromtheverticalmakingsurethatthereisenoughclearanceforstrainerremovalatgrade.

ConsiderationshallbegiventothehandlingoflargeTtypestrainercovers,andapermanenthandlingdevice(e.g.adavit)suppliedifaccessbymobileequipmentisnotpossible.

6.5COMMONSPARE

Occasionally,onepumpisinstalledasacommonsparebetweentwootherpumpsindifferentservices.Thepumpmustbemanifoldedinsuchawaythataccomplishesthis.Figure6illustratesanarrangementcommonlyused.



PipingforPumpswithacommonSpare

7.0CENTRIFUGALPUMPPIPINGLAYOUT

7.1HORIZONTALCENTRIFUGALPUMPS

Horizontalcentrifugalpumpsusuallyfitintothreecategories:

(1)EndSuctionTopDischarge(2)TopSuctionTopDischarge(3)SideSuctionSideDischarge

Themostcommonareendsuctionortopsuction.Suctionpipingshallbesupportedatgradebelowtheelbowforendsuctionpumps.Thedischargeline(topdischarge)shallbesupportedfromoverheadsteelwheneverpossibletoallowasmuch free area aspossible around thepump foroperation/maintenance.Figure 7 illustrateshowpipingmaybedesignedforthesepumps.



TypicalarrangementforEnd/TopSuctionCentrifugalPumps

7.1.1TypicalEndSuctionTopDischargearrangement

Figures4&5showcommonpipingarrangementsforendsuctiontopdischargecentrifugalpumps.Thesuctionlineshallhaveastraightrunbetweenthesuctionnozzleandthefirstelbow,tee,valve,reducerorpermanentstrainerasdictatedbythetypeofpumpand/ormanufacturersrecommendation.

7.1.2SideSuction/SideDischargePumpPiping

Pumpsmaybesinglestageormultistage.Multistagepumpsareusuallysidesuctionsidedischarge.Thesepumpsrequire significantlymore space, and present special layout considerations. The pump suction line for side suctionpumps shallhaveaminimumstraight runof threepipediameters (fornonAPIpumps)or fivepipediameters (forAPIpumps)betweenthesuctionflangeandthefirstelbow,tee,valve,reducerandpermanentstrainer.Ifahorizontalsuctionlinecannotbeavoided,thenthestraightrunlengthshouldbefivediametersminimumforallpumps(Figure8).



PipingArrangementforSideSuctionSideDischargePumps

7.2VERTICALCENTRIFUGALPUMPPIPING

Verticalcentrifugalpumpsmaybeinline,can(selfcontained)orsumppumps.Inlinepumpsaremountedinthelineandsupportedbythepipingasthenameimplies.Apedestal isoftenrequiredfor larger inlinepumpsorwheretheload is toohigh for thenozzles tohandle.Thedesignermust consider access formaintenanceandoperation in thesamewayasforhorizontalpumps.

Verticalcantypepumpsareinstalledinaconcretecylinderbuttheprocessfluidiscompletelycontainedinthepump"can." They are used when there is a high NPSH requirement or at surface condensers. This allows the surfacecondenser to bemounted at a lower elevation.The same is true for a vessel connected to a vertical canpump.Theprimaryconcernforthedesigneristoprovideadequateoverheadclearancetoremovethepumpformaintenance.

Verticalsumppumpsareusuallyusedtopumpwasteproductsorwaterfromacollectionsump.Hereagainaprimaryconcernistoprovideadequateoverheadclearancetoremovethepumpformaintenance.Theclearancerequirements,between the sumpwalls or bottom and the pumps inlet nozzle aswell as the pumps lengthmust be given carefulconsiderationduringthelayoutphaseoftheproject.ThesumpdesignatthepumpintakeshallbebasedonHydraulicInstituteStandards.

8.0RECIPROCATINGPUMPPIPING

Reciprocatingpumpsareusedwhenhighhead is required.Thesepumpsrequireapressurereliefvalve (PRV) tobeinstalledbetweenthepumpandthedischargeblockvalve.ThePRVcanbeexternal,inthepiping,orintegralwiththepumpcasing.



Due to the pulsating action of reciprocating pumps, the designer must consider space requirements for pulsationdampeners.Theseareusuallyfurnishedwiththepumpbuttakeupadditionalspace.

Pumpaccessisevenmoreimportantforreciprocatingpumpssincetheyrequiremoremaintenancethanotherpumps.Do not install any bend (i.e. 90 degree elbow) directly adjacent to the pump discharge. For typical egress andclearancerequirements,refertoDesignGuideforCompressorPipingLayout(ReciprocatingCompressors)3DGP2200008.

Thedischargepulsationdampenermustbeinstalledasclosetothedischargeaspossible.Pipesupportsmustbegivenspecialconsiderationduetothepulsations.

9.0ROTARYPUMPPIPING

Rotarypumpsareused forveryheavyorviscous fluids.Theydeliveraconstantpulsationfree flow.Piping for thesepumps is very similar to thatof centrifugalpumpsbut isusually characterizedby theabsenceofblockvalves in thesuction and discharge piping. If block valves are used, a pressure relief valvemust be installed between the pumpdischargeandtheblockvalve.ThePRVdischargeisusuallyroutedbacktothepumpsuction.

10.0PUMPSOPERATINGBELOWATMOSPHERICPRESSURE

Pumpsoperatingbelowatmosphericpressure (e.g.VacuumTowerBottomsPumps)present special problems. Sincethe systemoperates at a negativepressure and veryhigh temperature, thepumpsmust be located very close to thesuction source. This is often directly below the tower or immediately outside the tower support columns. PumpslocateddirectlybeneaththetowercanbemountedonaspecialspringbaseasshowninFigure9.

TypicalPumpSuctionPipingatVacuumTower



11.0AUXILIARYPIPING

Consideration must be given to lube oil and seal oil systems and any cooling water requirements. Care must beexercised not to block access to the pump seals, bearings, seal pots, starter button stations and motor conduitconnectionwhen routing these lines. (Figure 10)Thepumpdata sheet shall alwaysbe reviewed tomake sure theserequirementsarenotmissed.Forverylargepumpsthesemaybeonseparateskids.

PreferredAuxiliaryPipingArrangementandAccessZones

Firewaterdelugepipingshallberoutedsothat itdoesnot interferewithpumpoperatingormaintenanceaccess. Ifthe deluge piping design is subcontracted, the vendors design should be checked to ensure that safety egress,operatingandmaintenanceaccesswaysaremaintained.

12.0FIELDWELDS

Considerationshouldbegiventotheplacementoffieldfitupweldsinshopfabricatedpiping2andlarger.Earlyintheproject,PlantDesignshouldreviewtheoptionswithConstructionandthedecisiondocumented.Optionsinclude:

(i) Tack weld the flange adjacent to the pump suction and discharge nozzles to permit piping installation inaccordancewiththemachineryflangefituprequirements.

(ii)Providefieldweldsthatallowfitupinthreedirections.

(iii)Nofieldweldsotherthanthoserequiredbyspooltransportationsizelimitations.

13.0STEAMTURBINEPIPING

Pipingatsteamturbinespresentsomewhatdifferentconsiderationsfromthatofpumps.Thepipingmustbedesignedtopreventthepossibilityofintroducingaslugofcondensateintotheturbine,whichcoulddestroytheturbinevanes.



The inletpipingmusthave theblockvalveorcontrolvalve installed in thehorizontal runwithadrip legandsteamtrap upstream of the valves whether the turbine is setup for manual or automatic operation. In cases where thethrottling valve is furnished with the turbine and located on the inlet nozzle, the drip leg and steam trap shall belocatedimmediatelyupstream.(Seefigure11).

TypicalSteamTurbinePiping

Reducersinstalledintheinletpipingtosteamturbinesshallbeeccentricwiththeflatsideonthebottomtopreventtheaccumulationofanyliquid.

14.0SUPPORTOFPUMPPIPING

Itispreferredthatpumpdischargepipingbesupportedfromoverheadsteelwheneverpossible.Thisallowspipingatthepumptoberemovedformaintenance.(Seefigure12).



PumpDischargePipingSupportOptions

Thepiping layoutmustpermitbothsuctionanddischargepipes tobesupported independentof thepump(s), suchthatverylittleloadistransmittedtothepumpcasing.

15.0DIFFERENTIALSETTLEMENT

Whendifferentialsettlement isaproblem, it ispreferredthatthepumpsuctionpipingbesupportedfromthepumpfoundation.ThiscanbeaccomplishedbyextendingthefoundationasshowninFigure13.



PumpSuctionSupportforDifferentialSettlementProblem

16.0REFERENCES

HydraulicInstituteStandardsPumpHandbook(ISBN0070333017)DesignGuideforGasCompressorPiping(ReciprocatingCompressors)3DGP2200008

Documents

Layout Explained _ PIPING GUIDE