BS EN 12954-2001 Cathodic protection of buried or immersed metallic structures - General principles and application for pipelines《埋于土内或浸于液体的金属结构的阴极保护 管道应用和一般原则》.pdf

1、BRITISH STANDARD BS EN 12954:2001 Cathodic protection of buried or immersed metallic structures General principles and application for pipelines The European Standard EN 12954:2001 has the status of a British Standard ICS 23.040.01; 77.060 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COP

2、YRIGHT LAWBS EN 12954:2001 This British Standard, having been prepared under the direction of the Electrotechnical Sector Committee, was published under the authority of the Standards Committee and comes into effect on 15 June 2001 BSI 06-2001 ISBN 0 580 37665 6 National foreword This British Standa

3、rd is the official English language version of EN 12954:2001. Reference should also be made to BS 7361, Code of practice for land and marine applications, which will eventually be withdrawn when all the CEN Standards relating to cathodic protection currently being prepared, are published. The UK par

4、ticipation in its preparation was entrusted to Technical Committee GEL/603, Cathodic protection, which has the responsibility to: A list of organizations represented on this committee can be obtained on request to its secretary. Cross-references The British Standards which implement international or

5、 European publications referred to in this document may be found in the BSI Standards Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Find” facility of the BSI Standards Electronic Catalogue. A British Standard does not purport to include all the

6、 necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. aid enquirers to understand the text; present to the responsible European committee any enquiri

7、es on the interpretation, or proposals for change, and keep the UK interests informed; monitor related international and European developments and promulgate them in the UK. Summary of pages This document comprises a front cover, an inside front cover, the EN title page, pages 2 to 31 and a back cov

8、er. The BSI copyright date displayed in this document indicates when the document was last issued. Amendments issued since publication Amd. No. Date CommentsEUROPEANSTANDARD NORMEEUROPENNE EUROPISCHENORM EN12954 January2001 ICS23.040.99;77.060 Englishversion Cathodicprotectionofburiedorimmersedmetal

9、licstructures Generalprinciplesandapplicationforpipelines Protectioncathodiquedesstructuresmtalliquesenterres ouimmergesPrincipesgnrauxetapplicationpourles canalisations KathodischerKorrosionsschutzvonmetallenenAnlagenin BdenoderWssernGrundlagenundAnwendungfr Rohrleitungen ThisEuropeanStandardwasapp

10、rovedbyCENon1December2000. CENmembersareboundtocomplywiththeCEN/CENELECInternalRegulationswhichstipulatetheconditionsforgivingthisEurope an Standardthestatusofanationalstandardwithoutanyalteration.Uptodatelistsandbibliographicalreferencesconcernings uchnational standardsmaybeobtainedonapplicationtot

11、heManagementCentreortoanyCENmember. ThisEuropeanStandardexistsinthreeofficialversions(English,French,German).Aversioninanyotherlanguagemadebytra nslation undertheresponsibilityofaCENmemberintoitsownlanguageandnotifiedtotheManagementCentrehasthesamestatusasthe official versions. CENmembersarethenatio

12、nalstandardsbodiesofAustria,Belgium,CzechRepublic,Denmark,Finland,France,Germany,Greece, Iceland,Ireland,Italy,Luxembourg,Netherlands,Norway,Portugal,Spain,Sweden,SwitzerlandandUnitedKingdom. EUROPEANCOMMITTEEFORSTANDARDIZATION COMITEUROPENDENORMALISATION EUROPISCHESKOMITEEFRNORMUNG ManagementCentre

13、:ruedeStassart,36B1050Brussels 2001CEN Allrightsofexploitationinanyformandbyanymeansreserved worldwideforCENnationalMembers. Ref.No.EN12954:2001EPage2 EN12954:2001 Contents Page Foreword 4 Introduction 4 1Scope 5 2Normativereferences 5 3Symbols,termsanddefinitions 6 3.1Symbols 6 3.2Termsanddefinitio

14、ns 6 4Principleandcriteriaofcathodicprotection 12 4.1Principleofcathodicprotection 12 4.2Criteriaofcathodicprotection 12 4.3Influenceofalternatingcurrentoncathodicallyprotectedstructures 15 5Prerequisitesforapplicationofcathodicprotection 15 5.1General 15 5.2Electricalcontinuity 15 5.3Electricalisol

15、ation 15 5.4Externalcoating 15 6Basedatafordesign 15 6.1General 15 6.2Structuredetails 16 6.3Coating 16 6.4Environment 16 6.5Pipelinesspecificdata 16 7Designandprerequisites 17 7.1General 17 7.2Electricalisolation 17 7.3Teststations 18 7.4Bonding 18 7.5Buriedsleevepipesforpipelines 18 7.6Wallentries

16、,restraints,saddlesandanchorsforpipelines 19 7.7Bridges 19 7.8Electricallyoperatedequipment 19 7.9Lightningprotection 19 7.10Equipmentforthereductionofa.c.interference 19 7.11Cathodicprotectionsystems 20 7.12Drainagestations 22 7.13Designanddesigndocuments 22 8Installationofcathodicprotectionsystems

17、 22 8.1General 22 8.2Cables 23 8.3Galvanicanodes 23 8.4Impressedcurrentsystems 23 8.5Teststations 24 8.6Drainagestations 24 8.7Asbuiltdocumentation 24 9Commissioning 25Page3 EN12954:2001 9.1Preliminarychecking 25 9.2Startup 25 9.3Verificationofthecathodicprotectioneffectiveness 25 9.4Installationand

18、commissioningdocuments 26 10Inspectionandmaintenance 26 10.1General 26 10.2Factorsinfluencinginspectionfrequency 26 10.3Inspection 27 10.4Maintenance 29 10.5Resultsofinspection 29 AnnexA(informative)a.c.interference 30 Bibliography 31 Table1Freecorrosionpotentials,protectionpotentialsandlimitingcrit

19、icalpotentialofsome commonmetalsinsoilandinfreshandsaltwater 14 Table2Frequencyoffunctionalchecks 28Page4 EN12954:2001 Foreword ThisEuropeanStandardhasbeenpreparedbyTechnicalCommitteeCEN/TC219“Cathodic protection“,thesecretariatofwhichisheldbyBSI. ThisEuropeanStandardshallbegiventhestatusofanational

20、standard,eitherbypublicationofan identicaltextorbyendorsement,atthelatestbyJuly2001,andconflictingnationalstandardsshallbe withdrawnatthelatestbyJuly2001. AccordingtotheCEN/CENELECInternalRegulations,thenationalstandardsorganizationsofthe followingcountriesareboundtoimplementthisEuropeanStandard:Aus

21、tria,Belgium,Czech Republic,Denmark,Finland,France,Germany,Greece,Iceland,Ireland,Italy,Luxembourg, Netherlands,Norway,Portugal,Spain,Sweden,SwitzerlandandtheUnitedKingdom. AnnexAisinformative. Introduction Thisstandardisapplicabletotheprotectionofalltypesofburiedorimmersedmetallicstructures especia

22、llypipelines.However,inordertoallowforstructureshavingspecificfeatureswithregardsto construction,commissioningoroperation,provisionhasbeenmadeforcomplementarystandardsto beusedinconjunctionwiththisonetodealwiththepeculiaritiesofsuchstructures. Cathodicprotectionisatechniquebasedontheapplicationofele

23、ctrochemicalprinciplesandcoversa widerangeofmaterialsandequipmenttogetherwithavarietyofmeasurementtechniques.Inorderto achieveeffectiveandefficientcathodicprotection,thedesign,installation,commissioning,inspection andmaintenanceshouldbeperformedbyadequatelytrained,experiencedandresponsiblepersonnel.

24、 Thisstandardaimstoensureeffectivecathodicprotectionandisthereforedirectedprimarilytothe abovepersonnel.Page5 EN12954:2001 1Scope ThisEuropeanStandardspecifiesthegeneralprinciplesfortheimplementationofasystemof cathodicprotectionagainstcorrosiveattacksonburiedorimmersedmetalstructureswithandwithout

25、theinfluenceofexternalelectricalsources. NOTE1 Theprotectionagainststraycurrentfromdirectcurrentsysteminfluencesisdealt inprEN50162:2000. Thisstandardindicatesconditionsandparametersthatshouldbemettoachievecathodicprotection aswellasrulesandproceduresthatshouldbefollowedfordesign,installation,commis

26、sioningand maintenanceoftheprotectivesystems. NOTE2 Clauses5to10dealmainlywiththecathodicprotectionofpipelinesbuttheyare applicabletootherstructures Thisstandardisapplicabletoexternalsurfacesofburiedorimmersedstructures.Itisnotapplicableto theprotectionofinternalpartsofstructurescontainingcorrosivel

27、iquids. NOTE3 ThisiscoveredbyprEN12499:1996. Whencathodicprotectionisnecessary,thisstandardisapplicabletostructurescoveredwithconcrete whicharethenburiedorimmersed.Itisnotapplicabletotheprotectionofsteelinreinforcedconcrete whichisburiedorimmersed. NOTE4 ThisiscoveredbyEN12696 Thisstandardisapplicab

28、leonlytothoseconstructionsinseawaterforwhichtheprotectivesystems wouldbeinstalledandcanbeinspectedonland. NOTE5 Suchconstructionsinseawateraregenerallyofsmallerlength,whetherornot theyformapartofalargerundergroundnetwork. NOTE 6 Otherconstructionsinseawateraredealtwithinotherstandards,e.g.for submar

29、inepipelinesseeEN12473. 2Normativereferences ThisEuropeanStandardincorporates,bydatedorundatedreferences,provisionsfromother publications.Thesenormativereferencesarecitedattheappropriateplacesinthetextandthe publicationsarelistedhereafter.Fordatedreferences,subsequentamendmentstoorrevisionofany ofth

30、esepublicationsapplytothisstandardonlywhenincorporatedinthisstandardbyamendmentor revision.Forundatedreferencesthelatesteditionofthepublicationreferredtoapplies(including amendments). prEN50162:2000, ProtectionagainstcorrosionbystraycurrentfromDCsystems EN12696, Cathodicprotectionofsteelinconcrete p

31、rEN13509:1999, CathodicProtectionMeasurementTechniques EN6007910,ElectricalapparatusforexplosivegasatmospheresPart10:Classificationof hazardousareas (IEC6007910:1995)Page6 EN12954:2001 EN6007914 ,ElectricalapparatusforexplosivegasatmospheresPart14:Electricalinstallationsin hazardousareas(otherthanmi

32、nes) (IEC6007914:1996) ENISO8044, Corrosionofmetalsandalloys;vocabulary 3Symbols,termsanddefinitions 3.1Symbols I Current E Potential R Resistance J Currentdensity U Voltage a.c. Alternatingcurrent d.c. Directcurrent E Ag Metalorstructuretoelectrolytepotentialwithrespecttoasilver/silverchloriderefer

33、ence electrode E Cu Metalorstructuretoelectrolytepotentialwithrespecttoacopper/saturatedcoppersulphate referenceelectrode E IRfree IRfreepotential E KCl Metalorstructuretoelectrolytepotentialwithrespecttoasilver/silverchloride/saturated potassiumchlorideelectrode E l Limitingcriticalpotential E n Fr

34、eecorrosionpotential E off Offpotential E on Onpotential E p Protectionpotential E Hg Metalorstructuretoelectrolytepotentialwithrespecttoamercury/calomel/saturated potassiumchlorideelectrode E H Metalorstructuretoelectrolytepotentialwithrespecttoastandardhydrogenelectrode E Zn Metalorstructuretoelec

35、trolytepotentialwithrespecttoazincelectrode I a Anodecurrentoutput I p Protectioncurrent I s Straycurrent J a.c. Alternatingcurrentdensity J p Protectioncurrentdensity R co Coatingresistanceorstructuretosoilresistance( ) r co Averagecoatingresistanceoraveragestructuretosoilresistance( m 2 ) T Temper

36、ature t Time Resistivity( m) 3.2Termsanddefinitions ForthepurposesofthisEuropeanStandardthefollowingtermsanddefinitionsapply. ForothertermsanddefinitionsrelatedtocorrosionrefertoENISO8044. 3.2.1 anaerobic lackoffreeoxygenintheelectrolyteadjacenttoametallicstructure 3.2.2 anodebackfill materialwithal

37、owresistivity,whichmaybemoistureretaining,immediatelysurroundingaburied anodeforthepurposeofdecreasingtheeffectiveresistanceoftheanodetotheelectrolytePage7 EN12954:2001 3.2.3 averagecoatingresistanceoraveragestructuretosoilresistance(r co ) valuederivedfromtheratioofthedifferencebetweentheONandOFFpo

38、tentialstotheprotection currentandthesurfaceareaofthestructureinquestion.ItisusuallyexpressedinOhm.squaremeter ( m 2 ) 3.2.4 backfill seeanodebackfill 3.2.5 blistering formationofswellingsonthesurfaceofanunbrokenthincoatingcausedbypermeationofwater, gasesandbymigrationofionsinthepresenceofanelectric

39、fieldbetweenthemetalandthecoating 3.2.6 bond metalconductor,usuallyofcopper,connectingtwopointsonthesameorondifferentstructures usuallywiththeintentionofmakingthepointsequipotential 3.2.7 buriedstructure anymetalconstructionbuiltorlaidbeneathgroundlevelorbuiltongroundlevelandthencoveredwith earth 3.

40、2.8 cathodicprotectionstation impressedcurrentorgalvanicanodestation 3.2.9 cathodicprotectionsystem entireinstallation,includingactiveandpassiveelements,thatprovidescathodicprotection 3.2.10 coatingdefect deficiencyintheprotectivecoating(e.g.holidays,porosity) 3.2.11 coatingresistanceorstructuretoso

41、ilresistance(R co ) electricalresistancebetweenacoatedmetalandtheelectrolyteexpressedinohms.Itisdetermined largelybythesizeandnumberofcoatingdefects,coatingporesandtheelectrolyteresistivity 3.2.12 continuitybond bonddesignedandinstalledspecificallytoensureelectricalcontinuityofastructure 3.2.13 copp

42、er/saturatedcoppersulphatereferenceelectrode referenceelectrodeconsistingofcopperinasaturatedsolutionofcoppersulphate 3.2.14 coupon representativemetalsampleusedtoquantifytheextentofcorrosionortheeffectivenessofapplied cathodicprotection 3.2.15 d.c.decouplingdevice protectivedevicethatwillconductwhe

43、npredeterminedthresholdvoltagelevelsareexceededPage8 EN12954:2001 NOTESomeofthesedevicespermitthedischargeofa.c.currentstoearthingsystems. Polarizationcells,sparkgaps,anddiodeassembliesareexamplesofsuchdevices. 3.2.16 d.c.tractionsystem electricaltractionsystempoweredbydirectcurrent NOTEIfthesesyste

44、mshavethereturncircuitearthedatmorethanonepointorarenot completelyisolatedtheycangeneratestraycurrentswhichmaycausecorrosiondamage. 3.2.17 d.c.industrialplant electricalsystem,otherthanatractionsystem,poweredbydirectcurrent NOTEIfthesesystemsusetheearthaspartofthereturncircuittheycangeneratestray currentswhichmaycausecorrosiondamage.Cathodicprotectionsystemsusetheearthasa partofthecircuit. 3.2.18 drainpoint locationofthenegativecableconnectiontotheprotectedstructurethroughwhichtheprotection currentreturnstoitss