GUIDE FORPVC PRESSURE FITTINGS
PVC PRESSURE FITTINGSTABLE OF CONTENTS
Introduction 3
StandardsandSpecifications 3
Products 4
Manufacturing Methods 8
FabricatedFittings 8
Injection-MoldedFittings 9
MachinedCouplings 9
CompatibilitywithDissimilarMaterials 9
Designing to Prevent Pipe Movement 10
InternallyRestrainedJoints 11
ExternalRestraintDevices 12
ConcreteThrustBlocks 13
Installation 13
Handling 13
PipeandFittingPreparation 13
JointAssembly 13
ChangesinDirection 14
AcceptanceTesting 14
MemberCompanyFittingsManufacturers 15
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PVC PRESSURE FITTINGSINTRODUCTION
ThisdocumenthasbeendevelopedbytheUni-BellPVCPipeAssociationfordesignandinstallationofgasketedPVCfittingswheregasketedPVCpressurepipeisusedinpotablewater,forcemain,pressureirrigation,andreclaimedwaterapplications.TheguideprovidesinformationongasketedPVCfittingsthatareavailableforvariousdimensionratiosandoutsidediametersofPVCpipethrough60-inch.ThisdocumentdoesnotincludeinformationonsolventweldedorfusiblePVCfittings.
STANDARDS AND SPECIFICATIONSProductstandardsusedinthisguideinclude:
• ASTMD2774,StandardPracticeforUndergroundInstallationofThermoplasticPressurePiping
• ASTMD3139,StandardSpecificationforJointsforPlasticPressurePipesUsingFlexibleElastomericSeals
• ASTMF477,StandardSpecificationforElastomericSeals(Gaskets)forJoiningPlasticPipe
• ASTMF1674,TestMethodforJointRestraintProductsforUsewithPVCPipe
• AWWAC605,UndergroundInstallationofPolyvinylChloride(PVC)andMolecularlyOrientedPolyvinylChloride(PVCO)PressurePipeandFittings
• AWWAC900,PolyvinylChloride(PVC)PressurePipeandFabricatedFittings,4-inchthrough60-inch(100mmthrough1500mm)
Note:In2016,AWWA’slatesteditionofC900consolidatedalldiameters4-inchthrough60-inchintoasinglestandard;therefore,allfabricatedfittingsandmachinedcouplingscannowbespecifiedbyreferencingtheC900standard.
• AWWAC907,Injection-MoldedPolyvinylChloride(PVC)PressureFittings,4-inchthrough12-inch(100mmthrough300mm),forWater,Wastewater,andReclaimedWaterService
• CSAB137.2,PVCInjection-MouldedGasketedFittingsforPressureApplications
• CSAB137.3,RigidPolyvinylChloride(PVC)PipeforPressureApplications
• FM1612,PolyvinylChloride(PVC)PipeandFittingsForUndergroundFireProtectionService
• NSF/ANSI14,PlasticsPipingSystemComponentsandRelatedMaterials
• NSF/ANSI61,DrinkingWaterSystemComponents–HealthEffects
• UL1285,StandardforPipeandCouplings,PolyvinylChloride(PVC),andOrientedPolyvinylChloride(PVCO)forUndergroundFireService
GUIDEFORPVCPRESSUREFITTINGS3
PVC PRESSURE FITTINGSPRODUCTSThedifferenttypesoffittingsareasfollows:
Teeshaveanoutstandinglegthatis90°fromthemain.
Crosseshavetwooutstandinglegsthatareoppositeeachother.
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PVC PRESSURE FITTINGSPRODUCTS (CONT.)
Bends can havestandardangles(11.25°,22.5°,45°and90°)oranycustom-builtanglefrom1°to90°.
Sweeps areusedtochangealignment/directionwhilereducinghydrauliclosses.Sweepsaretypicallyavailablefrom1°to5°.
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PVC PRESSURE FITTINGSPRODUCTS (CONT.)
Couplings/Sleevesareusedtojointwopipesthathavethesamediameter.Thesehavemultipleapplicationsincluding:
• Tie-inconnectionstoexistinglines
• Connectingshortlengthsofpipe
• Repairingdamagedpipelines
• Changingpipelinedirection(high-deflectioncoupling)
Reducers/Tapers/Adaptersareusedtotransitionbetweentwodifferentpipediameters.
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PVC PRESSURE FITTINGSPRODUCTS (CONT.)
Tapped Couplingsareone-piecefittingswithpre-moldedthreadsforservicetaps.Tappedcouplingsareavailabletoaccommodatevariousmainlinesizeswithnumeroustapconfigurations.
Plugs/Capsaredesignedforstoppingflowonasegmentofpipe.Plugsareusedatdeadends.
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PVC PRESSURE FITTINGSPRODUCTS (CONT.)
MANUFACTURING METHODSTherearethreemanufacturingmethodsusedforAWWAPVCfittings.Allthreetypesusegasketedpush-onjointsandtheinternalpressurecapacityisequaltoorgreaterthanthatofthepipepressurerating.
FABRICATED FITTINGS
FabricatedfittingsareconstructedfromsectionsofPVCpipemeetingtherequirementsoftheAWWAC900standard.Theirconstituentpartsarethesameasthepipelinewithwhichtheywillbeused.ThebodyofthefittingisextrudedPVCpipethathasalreadypassedthestandard’stestingrequirements.Fabricatedfittingsincludesinglethermoformedbendsandcouplers.Aswell,multiplesegmentsofPVCpipecanbecutintowedgeshapes,orpreparedtoacceptleginsertions,andjoinedunderfactory-controlledconditionstoformanessentiallyhomogeneousstructure.Reinforcementmaybeappliedandpermanentlybondedtotheoutsidesurfacesofthefittings.
Availableproductsinclude:• Tees• Crosses• Bends(standardorcustomangles)• Couplings• Reducers• Adapters• Tapers
Custom Productscanbemanufacturedandareavailableinpush-onorrestrainedjoint.
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PVC PRESSURE FITTINGSFabricatedPVCfittingsareavailableforanysizePVCpipefrom4-inchthrough60-inch.Fabricatedfittingsare availableinmultiplepressureclassesandhavethesameorgreaterpressureclassasthePVCpipetowhichtheyarejoined.PleaseuseAWWAC900forfabricatedfittingsrecommendedspecifications.
INJECTION-MOLDED FITTINGS
Injection-moldedfittingsaremanufacturedbyinjectingPVCcompoundintoamoldcavityperAWWAC907.ThestandardrequiresthateachfittingbemadefromPVCcompoundwithaminimumHydrostaticDesignBasisof4,000psiandashort-termstrengthof6,400psi.Qualificationtestsmustproducealong-termpressurestrengthof470psi.Injection-moldedPVCfittingshaveawallthicknessaminimumof25%thickerthanDR18pipe.
Availableproductsinclude:• Bends(standardorcustomangles)• Couplings• Tees• Reducers• Adapters• Plugs• Tappedcouplings
Injection-moldedfittingsareavailablefrom4-inchto12-inchdiametersinpressureClass235psi.
MACHINED COUPLINGS MachinedcouplingsareconstructedfromsectionsofPVCpipemeetingtherequirementsoftheAWWAC900standard.TheyareproducedfromacombinationofmoldingandfabricatingmethodsandavailableforanysizePVCpipefrom4-inchthrough60-inch.PleasereferenceAWWAC900forfabricatedfittingsrecommendedspecifications.
COMPATIBILITY WITH DISSIMILAR MATERIALSPipesandfittingsmadefromPVCandDuctileIron(DI)usethesameoutsidediameterregimen,meaningthattheoutsidediametersspecifiedinbothproductstandardsareidentical.(Note:CIOD=CastIronOutsideDiameter,whichisthesameascastironpipesize.)PVCfabricatedfittingsandinjection-moldedfittingsareavailableinCIODandIronPipeSize(IPS).
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PVC PRESSURE FITTINGSTransitioningfromaPVCpipeorfittingintoaDIpipeorfittingiseasilyaccomplishedwheninsertingPVCspigotsintoironbells.Inthissituation,acouplingisnotnecessary.IfmakingthistransitionrequiresaDIspigotintoaPVCbell,transitioncouplingsarenecessary.Checkwithamanufacturerifconnectingtootherdiameterregimens.NOTE: Never insert a DI spigot into a PVC bell. ThisisbecauseDIpipeoutsidediametersareheldtotighttolerancesintheinsideofthebellandtheoutsideofthespigot,whiletheoutsideoftheremainderofthebarrelofthepipeisheldtoloosertolerances.Asaresult,theODoffield-cutDIpipesmayvary.TransitioncouplingsprovidewatertightjointsbetweenPVCandDIpipes.Typicalproductsincludesolid-sleevecouplingsormechanical-compressioncouplings.
DESIGNING TO PREVENT PIPE MOVEMENTLongitudinalthrustforcesmaydevelopinapressurizedpipingsystem.Typicaloptionsforbalancinghydrostaticthrustforcesinclude:
• Internallyrestrainedjoints
• Externalmechanicalrestraintdevices
• Concretethrustblocks
Wheninternalorexternalrestraintisused,thepipelinebecomesitsownthrustblock.Byrestrainingcertainjointsatbendsandalongthepipeline,theresultantthrustforceistransferredtothesurroundingsoilbythepipelineitself.Inaproperlydesignedpipelineusingrestrainedjoints,thrustforcesareresistedbythebearingstrengthofthesoilandthefrictionalresistancebetweenthepipeandsoil.
Thrustforcesaredevelopedat:
• Changesinhorizontalandverticaldirectionatfittings(tees,bends,wyes,andcrosses)
• Changesinpipesize(reducers)
• Deadends(plugs,closedvalves,andhydrants)
Sizeandtypeofinternalorexternalrestraintdevicesorthrustblockingdependon:
• Maximumsystempressure(includingfield-testingpressures)
• Pipesize
• Typeoffittingorappurtenance
• Lineprofile(horizontalorverticalbends)
• Bearingstrengthofundisturbedsoil
• Depth of cover
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GUIDEFORPVCPRESSUREFITTINGS11
PVC PRESSURE FITTINGSTheselectionoftheappropriatemethodforprovidingthrustrestraintmustbebasedontheconsiderationofpresentandfutureconditions.Long-rangeconsiderationsshouldinclude:
• Thepredictionoffutureactivitiesaroundthebendsthatmightjeopardizethewatermain,suchasconstructionofotherservices,changesingroundwaterlevels,andchangesingroundelevation.
• Theabilitytocontrolandmonitoractivitiesaroundthebends,especiallythoseoneasementsawayfrom publicsurveillance.
Computerprogramsareavailabletocalculaterequiredrestrainedlengthsandtoguidetheusertosuggestedconfigurations.Clickhereforathrustrestraintcalculationwebsite.
INTERNALLY RESTRAINED JOINTS
ForeachofthePVCpiperestraintproductslistedbelow,designmethodsareavailablefromthemanufacturer.
Spline-Lock Gasketed Joint-Thisjointusesagasketedcouplingorintegralbellwithnylonsplinesthatextendintoalignedgroovesinthecouplingbellandthepipespigot.
Grip-Ring Gasketed Joint-Restraintinternaltothebellisavailableforbell-and-spigotpipeandfabricatedPVCfittings.
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PVC PRESSURE FITTINGS
Pin-and-Groove Gasketed Joint-Agrooveontheoutsideofthepipespigotalignswithholesspacedaroundthepipebell.Pinsaredriventhroughtheholesintothegroovestopreventmovement.
EXTERNAL RESTRAINT DEVICES
Inordertoproperlyrestrainafitting,itisessentialthattheinstallationinstructionsoftherestraint-devicemanufacturerbefollowed.Correctlubrication,bolt-torque,andtighteningpatternarecrucialtomakingaproperjoint.Fortheexternaljointrestraintproductsbelow,designmethodsareavailablefromthemanufacturer.
External Joint Restraint-Thesedevicesclamptothewallofthepipeandtiebacktoamatingcollaronthefittingorpipebell.
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PVC PRESSURE FITTINGSCONCRETE THRUST BLOCKS Onemethodofresistingtheunbalancedforcesinawatermainisconcretethrustblocks.Thedisadvantageofthrustblocksisthattheyrelyontheundisturbedsoilbehindthethrustblock.Theirreliabilitymaybecompromisediffuturediggingoccursnearthethrustblock.Thrustblocksshouldbeshownonthewatermainsystemplansandacautionarynoteaboutdiggingintheareashouldbeonthedrawing.Insomecases,theactualsizeoftheblockwillprohibititsuse.Thisisparticularlytrueinmanyurbanareas.Inpoorsoilconditions,largeandheavythrustblocksmaycausesettlementofthepipe.SeeChapter11oftheHandbook of PVC Pipe Design and Constructionformoreinformation.
INSTALLATIONFittingsshouldbeinstalledperthegeneralrequirementsofAWWAC605andASTMD2774.
HANDLING
Placethepipeandfittingsintothetrenchusingropesandskids,slingsonthebackhoebucket,orbyhand.Donotthrowpipeorfittingsintothetrenchorallowanypartofthepipetomakeanunrestrainedfallontothetrenchbottom.Ensurethattherearenodamagedmaterialsbeforeassemblybegins.
PIPE AND FITTING PREPARATION
Thepipeendshouldbesquareandbeveled.Thebevelshouldbecutatapproximately15°andshouldbeabout¾-inchlong.Removeanyburrsandridgesonthepipe.Measurethefittingbelldepthandmarkthepipewithaninsertionline.Followthefittingmanufacturer’srecommendedinsertiondepth.Notethatfittinginsertiondepthsareoftendifferentfromthefactoryinsertionlinesmarkedonthepipeandthereforeitisimportanttomeasureandfield-marktheinsertionlinetoensureaproperlyassembledjoint.
Cleanalldebrisfromthebellareasofthefitting.Checkthatthegasketisfullyseatedinthegroovewithnoraisedareas.
Lubricatepipeandfittingperthefittingmanufacturer’sinstructions.
JOINT ASSEMBLY
Alignthepipewiththefittingandpushtogetherbyhandorwithprybars(usingwoodblocksbetween the barsandthefittings).Insertuntiltheinsertionlineisevenwiththeedgeofthefittingbell.Properinsertionisimportantbecauseover-insertionistheprimarycauseofleaksinfittings.Donotinstallusingabackhoe.
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PVC PRESSURE FITTINGSCHANGES IN DIRECTION Do notdeflectthepipeinthefittingbellmorethanthefittingmanufacturer’srecommendation.Becarefulthatover-insertionorover-deflectiondoesnotoccurwheninstallingadjoininglengthsofpipe.Pointloadingcausedbyexcessivedeflectioncancreatedistortionandcauseleaksand/orbreakage.Followthefittingmanufacturer’srecommendationsforjoint-deflectionlimits.Followthepipemanufacturer’srecommendationsfor pipe bending.
ACCEPTANCE TESTING
TestPressure:Ahydrostatictestpressureof150%ofthenormaloperatingpressureisgenerallysufficient.Inno caseshouldthetestpressureexceedthedesignpressureclass/ratingforanysystemcomponentincludingpipe,thrustrestraint,valve,fitting,orotherappurtenance.
NOTE: For safety reasons, compressed air or gas should not be used for pressure rating.
GUIDEFORPVCPRESSUREFITTINGS15
PVC PRESSURE FITTINGSMEMBER COMPANY FITTINGS MANUFACTURERS
Forfurtherinformation,pleasecontactaUni-BellPVCPipeAssociationfittingsmanufacturer:
www.napcopipe.com
www.ipexna.com
UNI-PUB-13-19 2.15.2019
UNI-BELL PVC PIPE ASSOCIATION 2711 LBJ Freeway, Suite 1000
Dallas, TX 75234(972) 243-3902
WWW.UNI-BELL.ORG