Designation:A268/A268M−10(Reapproved2016)StandardSpecificationforSeamlessandWeldedFerriticandMartensiticStainlessSteelTubingforGeneralService1ThisstandardisissuedunderthefixeddesignationA268/A268M;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.ThisstandardhasbeenapprovedforusebyagenciesoftheU.S.DepartmentofDefense.1.Scope1.1Thisspecification2coversanumberofgradesofnominal-wall-thickness,stainlesssteeltubingforgeneralcorrosion-resistingandhigh-temperatureservice.Mostofthesegradesarecommonlyknownasthe“straight-chromium”typesandarecharacterizedbybeingferromagnetic.Twoofthesegrades,TP410andUNSS41500(Table1),areamenabletohardeningbyheattreatment,andthehigh-chromium,ferriticalloysaresensitivetonotch-brittlenessonslowcoolingtoordinarytemperatures.Thesefeaturesshouldberecognizedintheuseofthesematerials.GradeTP439isusedprimarilyforhot-watertankserviceanddoesnotrequirepost-weldheattreatmenttopreventattackoftheheataffectedzone.1.2Anoptionalsupplementaryrequirementisprovided,andwhendesired,shallbesostatedintheorder.1.3Thevaluesstatedineitherinch-poundunitsorSIunitsaretoberegardedseparatelyasstandard.Withinthetext,theSIunitsareshowninbrackets.Thevaluesstatedineachsystemmaynotbeexactequivalents;therefore,eachsystemshallbeusedindependentlyoftheother.Combiningvaluesfromthetwosystemsmayresultinnon-conformancewiththestandard.Theinch-poundunitsshallapplyunlessthe“M”designationofthisspecificationisspecifiedintheorder.2.ReferencedDocuments2.1ASTMStandards:3A480/A480MSpecificationforGeneralRequirementsforFlat-RolledStainlessandHeat-ResistingSteelPlate,Sheet,andStripA763PracticesforDetectingSusceptibilitytoIntergranularAttackinFerriticStainlessSteelsA1016/A1016MSpecificationforGeneralRequirementsforFerriticAlloySteel,AusteniticAlloySteel,andStainlessSteelTubesE213Practicefor...
