Designation:A381/A381M−18StandardSpecificationforMetal-Arc-WeldedCarbonorHigh-StrengthLow-AlloySteelPipeforUseWithHigh-PressureTransmissionSystems1ThisstandardisissuedunderthefixeddesignationA381/A381M;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope*1.1Thisspecificationcoversstraightseam,double-submerged-arc-weldedcarbonorhigh-strengthlow-alloysteelpipe(Note1)suitableforhigh-pressureservice,16in.[400mm]andlargerinoutsidediameter,withwallthicknessesfrom5⁄16to11⁄2in.[8to40mm].Thepipeisintendedforfabricationoffittingsandaccessoriesforcompressororpump-stationpiping.Pipeorderedtothisspecificationshallbesuitableforbending,flanging,corrugating,andsimilaroperations.NOTE1—AcomprehensivelistingofstandardizedpipedimensionsiscontainedinANSIB36.10.NOTE2—Theterm“doublewelded”iscommonlyusedinthegasandoiltransmissionindustry,forwhichthispipeisprimarilyintended,toindicateweldingwithatleasttwoweldpasses,ofwhichoneisontheoutsideofthepipeandoneontheinside.Forsomesizesofthepipecoveredbythisspecification,itbecomesexpedienttousemanualwelding,inwhichcasetheprovisionsofNote3shallbefollowed.1.2Thisspecificationisexpressedinbothinch-poundunitsandinSIunits;however,unlessthepurchaseorderorcontractspecifiestheapplicableMspecificationdesignation(SIunits),theapplicableinch-poundunitsshallapply.Thevaluesstatedineitherinch-poundunitsorSIunitsaretoberegardedseparatelyasstandard.Withinthetext,theSIunitsareshowninbrackets.Thevaluesstatedineachsystemmaynotbeexactequivalents;therefore,eachsystemshallbeusedindependentlyoftheother.Combiningvaluesfromthetwosystemsmayresultinnonconformancewiththestandard.1.3Elevenclassesofpipe,basedonminimumyieldpointrequirements,arecoveredasindicatedinTable1.1.4Thisspecificationidentifiesvariousthermaltreatments(3.1.9,5.5,and5.6).1.5Thefollowingcaveat...
