BS 4921-1988 钢铁件上的镀锌层规范

BRITISHSTANDARDBS4921:1988SpecificationforSherardizedcoatingsonironorsteelUDC669.58:669.1.056.9BS4921:1988ThisBritishStandard,havingbeenpreparedunderthedirectionoftheSurfaceCoatings(otherthanPaints)StandardsCommittee,waspublishedundertheauthorityoftheBoardofBSIandcomesintoeffecton29February1988©BSI01-1999FirstpublishedFebruary1973FirstrevisionFebruary1988ThefollowingBSIreferencesrelatetotheworkonthisstandard:CommitteereferenceSRC/1Draftforcomment86/54177DCISBN0580164136CommitteesresponsibleforthisBritishStandardThepreparationofthisBritishStandardwasentrustedbytheSurfaceCoatings(otherthanPaints)StandardsCommittee(SRC/-)toTechnicalCommitteeSRC/1,uponwhichthefollowingbodieswererepresented:BritishConstructionalSteelworkAssociationLtd.BritishIndustrialFastenersFederationBritishLockManufacturers’AssociationBritishMalleableTubeFittingsAssociationBritishMetalFinishingSuppliers’AssociationBritishSteelIndustry(WireSection)BritishTelecommunicationsplcElectricitySupplyIndustryinEnglandandWalesElectronicEngineeringAssociationGalvanizers’AssociationInstituteofMetalFinishingMetalFinishingAssociationMinistryofDefenceSocietyofMotorManufacturersandTradersLtd.SpringResearchandManufacturers’AssociationTelecommunicationEngineeringandManufacturingAssociation(TEMA)ZincAlloyRust-proofingCo.Ltd.ZincDevelopmentAssociationAmendmentsissuedsincepublicationAmd.No.DateofissueCommentsBS4921:1988©BSI01-1999iContentsPageCommitteesresponsibleInsidefrontcoverForewordii1Scope12Definitions13Thickness14Coatingmaterial1AppendixAGuidanceoninformationtobesupplied2AppendixBInformationforguidance2AppendixCMethodsfordeterminationofcoatingthickness3Table1—Thicknessofcoating1Table2—Additionalclearanceallowancesonscrewthreads3PublicationsreferredtoInsidebackcoverBS4921:1988ii©BSI01-1999ForewordThisrevisionofthisBritishStandardhasbeenpreparedunderthedirectionoftheSurfaceCoatings(otherthanPaints)StandardsCommittee.itsupersedesBS4921:1973,whichiswithdrawn.Inthisrevision,therequirementsofthisspecificationarerestrictedtothosewhichdefineminimumcoatingthicknessandthematerialtobeappliedinthecoatingprocess.InformationtobeagreedbetweentheinterestedpartiesisnolongerincludedinthisspecificationbutinsteadcomprisesAppendixA,whichisintendedforguidancefororderingpurposes.Twoclassesofsherardizedcoatingthicknessareincludedandtheseareconsideredadequateformostrequirements.Themicroscopicalmethodofthicknessmeasurementisgivenasthereferencemethodincasesofdispute.Othertestmethods,includingtheuseofelectronicandmagneticmeasuringdevicesandthestrippingtest,maybeusedwhendesiredparticularlyforproductioncontrolpurposes.Productcertification.UsersofthisBritishStandardareadvisedtoconsiderthedesirabilityofthirdpartycertificationofproductconformitywiththisBritishStandardbasedontestingandcontinuingsurveillance,whichmaybecoupledwithassessmentofasupplier’squalitysystemsagainsttheappropriatePartofBS5750.EnquiriesastotheavailabilityofthirdpartycertificationschemeswillbeforwardedbyBSItotheAssociationofCertificationBodies.Ifathirdpartycertificationschemedoesnotalreadyexist,usersshouldconsiderapproachinganappropriatebodyfromthelistofAssociationmembers.ABritishStandarddoesnotpurporttoincludeallthenecessaryprovisionsofacontract.UsersofBritishStandardsareresponsiblefortheircorrectapplication.CompliancewithaBritishStandarddoesnotofitselfconferimmunityfromlegalobligations.SummaryofpagesThisdocumentcomprisesafrontcover,aninsidefrontcover,pagesiandii,pages1to4,aninsidebackcoverandabackcover.Thisstandardhasbeenupdated(seecopyrightdate)andmayhavehadamendmentsincorporated.Thiswillbeindicatedintheamendmenttableontheinsidefrontcover.BS4921:1988©BSI01-199911ScopeThisBritishStandardspecifiesminimumthicknessrequirementsfortwoclassesofcoatingsconsistingsubstantiallyofzincappliedbythesherardizingprocesstosteelarticlesandtogreyandmalleableironcastings.Italsospecifiesrequirementsforthezincusedduringthesherardizingprocess(butseetheforewordandthenotetoclause4).NOTE1GuidanceisgivenonrequirementswhichrequireagreementbetweentheinterestedpartiesinAppendixAandgeneralguidanceonsherardizingisgiveninAppendixB.NOTE2Thetitlesofthepublicationsreferredtointhisstandardarelistedontheinsidebackcover.2DefinitionsForthepurposesofthisBritishStandard,thefollowingdefinitionsapply.NOTEDefinitions2.1to2.2aretakenfromBS5411-1.2.1significantsurfacethatpartofthearticlecoveredortobecoveredbythecoatingsandforwhichthecoatingisessentialforserviceabilityand/orappearance2.2measuringareatheareaofthesignificantsurfaceoverwhichasinglemeasurementismade“measuringarea”forthefollowingmethodsisdefinedas:a)foranalyticalmethods:theareafromwhichthecoatingisremoved;b)fortheanodicdissolutionmethod:theareaenclosedbythesealingringofthecell;c)forthemicroscopicalmethod:theplaceatwhichasinglemeasurementismade;d)fornon-destructivemethods:theprobeareaortheareainfluencingthereading.2.3referenceareatheareawithinwhichaspecifiednumberofsinglemeasurementsisrequiredtobemade2.4localthicknessthemeanofthethicknessmeasurements,ofwhichaspecifiednumberismadewithinareferencearea2.5m