Designation:A688/A688M−18StandardSpecificationforSeamlessandWeldedAusteniticStainlessSteelFeedwaterHeaterTubes1ThisstandardisissuedunderthefixeddesignationA688/A688M;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope*1.1Thisspecification2coversseamlessandweldedauste-niticstainlesssteelfeedwaterheatertubesincludingthosebent,ifspecified,intotheformofU-tubesforapplicationintubularfeed-waterheaters.1.2Thetubingsizescoveredshallbe5⁄8to1in.[15.9to25.4mm]inclusiveoutsidediameter,andaverageorminimumwallthicknessesof0.028in.[0.7mm]andheavier.1.3ThevaluesstatedineitherSIunitsorinch-poundunitsaretoberegardedseparatelyasstandard.Withinthetext,theSIunitsareshowninbrackets.Thevaluesstatedineachsystemmaynotbeexactequivalents;therefore,eachsystemshallbeusedindependentlyoftheother.Combiningvaluesfromthetwosystemsmayresultinnon-conformancewiththestandard.1.4Thisinternationalstandardwasdevelopedinaccor-dancewithinternationallyrecognizedprinciplesonstandard-izationestablishedintheDecisiononPrinciplesfortheDevelopmentofInternationalStandards,GuidesandRecom-mendationsissuedbytheWorldTradeOrganizationTechnicalBarrierstoTrade(TBT)Committee.2.ReferencedDocuments2.1ASTMStandards:3A262PracticesforDetectingSusceptibilitytoIntergranularAttackinAusteniticStainlessSteelsA480/A480MSpecificationforGeneralRequirementsforFlat-RolledStainlessandHeat-ResistingSteelPlate,Sheet,andStripA941TerminologyRelatingtoSteel,StainlessSteel,RelatedAlloys,andFerroalloysA1016/A1016MSpecificationforGeneralRequirementsforFerriticAlloySteel,AusteniticAlloySteel,andStainlessSteelTubesE112TestMethodsforDeterminingAverageGrainSizeE527PracticeforNumberingMetalsandAlloysintheUnifiedNumberingSystem(UNS)2.2OtherStandard:SAEJ1086PracticeforNumberingMetalsandAlloys(UNS)43.Terminology3.1DefinitionsOfTerms—Fordefi...
