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StandardPracticePipelineExternalCorrosionDirectAssessmentMethodologyThisNACEInternationalstandardrepresentsaconsensusofthoseindividualmemberswhohavereviewedthisdocument,itsscope,andprovisions.Itsacceptancedoesnotinanyrespectprecludeanyone,whetherheorshehasadoptedthestandardornot,frommanufacturing,marketing,purchasing,orusingproducts,processes,orproceduresnotinconformancewiththisstandard.NothingcontainedinthisNACEInternationalstandardistobeconstruedasgrantinganyright,byimplicationorotherwise,tomanufacture,sell,oruseinconnectionwithanymethod,apparatus,orproductcoveredbyLettersPatent,orasindemnifyingorprotectinganyoneagainstliabilityforinfringementofLettersPatent.Thisstandardrepresentsminimumrequirementsandshouldinnowaybeinterpretedasarestrictionontheuseofbetterproceduresormaterials.Neitheristhisstandardintendedtoapplyinallcasesrelatingtothesubject.Unpredictablecircumstancesmaynegatetheusefulnessofthisstandardinspecificinstances.NACEInternationalassumesnoresponsibilityfortheinterpretationoruseofthisstandardbyotherpartiesandacceptsresponsibilityforonlythoseofficialNACEInternationalinterpretationsissuedbyNACEInternationalinaccordancewithitsgoverningproceduresandpolicieswhichprecludetheissuanceofinterpretationsbyindividualvolunteers.UsersofthisNACEInternationalstandardareresponsibleforreviewingappropriatehealth,safety,environmental,andregulatorydocumentsandfordeterminingtheirapplicabilityinrelationtothisstandardpriortoitsuse.ThisNACEInternationalstandardmaynotnecessarilyaddressallpotentialhealthandsafetyproblemsorenvironmentalhazardsassociatedwiththeuseofmaterials,equipment,and/oroperationsdetailedorreferredtowithinthisstandard.UsersofthisNACEInternationalstandardarealsoresponsibleforestablishingappropriatehealth,safety,andenvironmentalprotectionpractices,inconsultationwithappropriateregulatoryauthoritiesifnecessary,toachievecompliancewithanyexistingapplicableregulatoryrequirementspriortotheuseofthisstandard.CAUTIONARYNOTICE:NACEInternationalstandardsaresubjecttoperiodicreview,andmayberevisedorwithdrawnatanytimeinaccordancewithNACEtechnicalcommitteeprocedures.NACEInternationalrequiresthatactionbetakentoreaffirm,revise,orwithdrawthisstandardnolaterthanfiveyearsfromthedateofinitialpublicationandsubsequentlyfromthedateofeachreaffirmationorrevision.Theuseriscautionedtoobtainthelatestedition.PurchasersofNACEInternationalstandardsmayreceivecurrentinformationonallstandardsandotherNACEInternationalpublicationsbycontactingtheNACEInternationalFirstServiceDepartment,1440SouthCreekDr.,Houston,Texas77084-4906(telephone+1281-228-6200).Reaffirmed2008-03-20Approved2002-10-11NACEInternational1440SouthCreekDr.Houston,Texas77084-4906+1281-228-6200ISBN1-57590-156-0©2008,NACEInternationalNACESP0502-2008(formerlyRP0502-2002)ItemNo.21097LiHongqi-InvoiceINV-176253-3JPVUI,downloadedon11/20/20087:58:27PM-Single-userlicenseonly,copyingandnetworkingprohibited.RP0502-20022The2002editionofRP0502wasapprovedasanAmericanNationalStandardbytheAmericanNationalStandardsInstitute(ANSI).Approvalofthe2008editionisexpectedbyAugust2008.LiHongqi-InvoiceINV-176253-3JPVUI,downloadedon11/20/20087:58:27PM-Single-userlicenseonly,copyingandnetworkingprohibited.SP0502-2008NACEInternationali________________________________________________________________________ForewordExternalcorrosiondirectassessment(ECDA)isastructuredprocessthatisintendedtoimprovesafetybyassessingandreducingtheimpactofexternalcorrosiononpipelineintegrity.Byidentifyingandaddressingcorrosionactivity,repairingcorrosiondefects,andremediatingthecause,ECDAproactivelyseekstopreventexternalcorrosiondefectsfromgrowingtoasizethatislargeenoughtoimpactstructuralintegrity.ECDAasdescribedinthisstandardpracticeisspecificallyintendedtoaddressburiedonshorepipelinesconstructedfromferrousmaterials.Othermethodsofaddressingexternalcorrosionononshoreferrouspipelines,suchaspressuretestingandin-lineinspection(ILI),arenotcoveredinthisstandardbutarecoveredinotherindustrystandards.Usersofthisstandardmustbefamiliarwithallapplicablepipelinesafetyregulationsforthejurisdictioninwhichthepipelineoperates.Thisincludesallregulationsrequiringspecificpipelineintegrityassessmentpracticesandprograms.Thisstandardisintendedforusebypipelineoperatorsandotherswhomustmanagepipelineintegrity.ECDAisacontinuousimprovementprocess.ThroughsuccessiveECDAapplications,apipelineoperatorshouldbeabletoidentifyandaddresslocationsatwhichcorrosionactivityhasoccurred,isoccurring,ormayoccur.OneoftheadvantagesofECDAisthatitcanlocateareaswheredefectscouldforminthefutureratherthanonlyareaswheredefectshavealreadyformed.PipelineoperatorshavehistoricallymanagedexternalcorrosionusingsomeoftheECDAtoolsandtechniques.Often,datafromabovegroundinspectiontoolshavebeenusedtolocateareasthatmaybeexperiencingexternalcorrosion.TheECDAprocesstakesthispracticeseveralstepsforwardandintegratesinformationonapipeline’sphysicalcharacteristicsandoperatinghistory(pre-assessment)withdatafrommultiplefieldexaminations(indirectinspections)andpipesurfaceevaluations(directexaminations)t