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Corrosion Control – Corrosion Mitigation & Cathodic Protection Regulatory requirements

Corrosion Control – Corrosion Mitigation & Cathodic Protection Regulatory requirements. P r e s e nt ed B y Thomas Finch N A CE S e nio r C orro s io n T ec hno l o g i s t.  Corro s ion Tro ub l eshooti n g  C ath o d ic Protection Tool s and E q ui p m ent

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Corrosion Control – Corrosion Mitigation & Cathodic Protection Regulatory requirements

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  1. Corrosion Control – Corrosion Mitigation & Cathodic Protection Regulatory requirements

  2. PresentedByThomas Finch NACESeniorCorrosionTechnologist

  3. CorrosionTroubleshooting CathodicProtectionToolsandEquipment EstablishingTestStations,andtheDifferenceBetweenTestPointsandTestStations MonitoringRequirements

  4. Thisseminarwillcoveronlyexternalcorrosionasit appliestopipelinesystems. We will be discussingThe Code ofFederal Regulations, CFR 49, Part 192, as it appliesto hazardousmaterialspipelines. For specificregulationsfor yourindustry, refer to any specificcodesorstatutes. Thematerialsinthiscoursemaybedownloadedto theCoursesite. Thankyou!

  5. Simplyput,theobjectiveofcathodicprotection istomakeallexposedexternalsurfacesofthe pipeline a cathode with respect corrosion cell Twotypesof cathodicprotection: to the basic • Sacrificial anode, where a more reactive metal is • connected to the pipeline, causing a galvanic corrosion cell where the anode is consumed, thus protecting the pipeline • Impressedcurrent,whereanelectricaldevice,calleda rectifier and an impressed-current ground bed are connectedtothe pipe ina waythat prevents corrosion

  6. Anode Cathod eAnode Cathod e AnodeC athode Anode C athod e Anode C athode Anode Cathod e Anode Cathode CathodeCathodeCathodeCathodeCathode CathodeCathodeCathodeCathodeCathode CathodeCathode Before theapplicationofCathodicProtection After the applicationof CathodicProtection Anode

  7. Impressed Current Cathodic Protection Sacrificial Anode Cathodic Protection

  8. AboutSacrificialAnodes

  9. About ImpressedCurrent

  10. Cathodic Protectioncan only be effective if thepipelineisinacommonelectrolytewiththecathodicprotectionsystem • Exampleswhere CP may notbeeffective: • AtmosphericCorrosion • Internalcorrosion • Pipeincongestedpipelinecorridors • Electricalshielding,suchaspipeinacasing,orpipe encased inconcrete,orneardenserock

  11. CorrosionTroubleshootingBasics

  12. Wewillcover: • CPTroubleshootingEquipment • Howtosetupa cathodicprotectionarea • DeterminingtheamountofCPTest Stationsneeded • Electricaltroubleshootingbasics

  13. A goodDigitalMultimeter(DMM) ACopper-coppersulfate(CuSO4)referenceelectrode(calleda“half-cell”) Goodquality Lowfrequencypipe/cablelocator Variousslideresistors (25,50,100Watt) A highquality CurrentInterrupter Miscellaneousjumperleads with alligator-style clips at each end

  14. Usinga DMMandhalf-cell,removethe half-cellcapbefore taking the reading,andreplacethe capafter reading. InordertominimizeIRdroperrorwhentaking P/Sreadings, you shouldalwaysplace the half-cellas closeas possible to the testedstructure.Itis acceptable to pourasmall amount ofwaterwhereyouwillembed thehalfcellin earth. Use theVDCsettingonthe DMM,and insertthe testleads intotheappropriateports toreadDCvolts.Place theblack(-) lead ontothehalf-cell,and the red (+)lead ontothe structure. Goodmetalcontactmust be madeonthestructureandhalf cell.

  15. Inaskingthe generalquestion,“Howmanytest pointswillIneed,toadequatelymonitora cathodic protectionarea?”the answerisnot a simpleone. In CFR 49,§192.469Externalcorrosioncontrol: Teststations,it states:“Eachpipelineunder cathodic protectionrequiredby thissubpartmust havesufficientteststationsor othercontactpointsforelectricalmeasurementtodeterminethe adequacyofcathodic protection.” 34606,Aug.16,1976] [Amdt.192–27,41FR

  16. §192.471 Externalcorrosioncontrol:Testleads. • (a)Eachtestleadwiremustbeconnectedtothe pipelinesoastoremainmechanicallysecureand electricallyconductive. • (b) Each test lead wire must be attached to the pipeline so as to minimize stressconcentration onthe pipe. • (c) Each bared test lead wire and bared metallic areaatpointofconnectiontothepipelinemust be coated withanelectrical insulatingmaterial coatingand the compatible withthe pipe insulationonthewire.

  17. Using a DMMandhalf-cellperforma random P/S survey ofthe area.Determineifthe systemmeets one ormoreCPcriteria.The more commoncriteria include:-.85Vdc,100 mVshift,and300 mVshift. Lessusedarethe E Log I andNet protectivecurrent criteria. Use the proceduresonthe slidesthatfollowto establishthe numberof teststationsyouwillneed. Foreaseofillustration,wewilluse the -.85 Vdc criterion.

  18. Ifthe initialrandomP/Ssurvey indicates that all readings meetthe criterion,usea jumperlead with alligatorclips,and shortan insulatorout.Thismay be locatedwherethepiping entersa building,orata metersetting.Thentake randomP/S readingsthroughoutthe testedsection. Ifthe entiresectionof pipe drops belowthecriterion,you mayonlyneedoneteststation,however,werecommendyou establisha minimumoftwo stations per section. Ifonlya portionofthe sectiondrops belowthe selected criterion,continuetothe pointwherethe readingsdonot drop,and thenshortoutthepiping inthe portionthatwas unaffected.Continuetesting untilyou establishall test stations withinthearea.

  19. Exampleofelectricaltesting for teststation setup: KNOWN INSULATOR UNKNOWN INSULATOR UNKNOWN INSULATOR KNOWN INSULATOR

  20. If yourinitialmonitoringindicatesthatthecriterionis not beingmet,thenthestepsbecomemorecomplex,butnot impossible. Inthis case, theremaybe: • An electricalshortonameteror other abovegroundpipelinecomponent. Examplesincludeafencecontactingameter, house pipingtouchingthemeterriser,or abad(shorted)insulatoron themetersetting. • A main-to-mainor main-to-serviceunderground contact. Examplesincludeawater or sewermaintouching agasmainor serviceline,or aCATVor satellitecablegrounded tothe riser. • Thesearenotall situationsthatmaycause thecathodic protectionsystemtobecomeunsuccessfulatprotectingthe pipeline.

  21. Youwillhave tolocateandclearall insulatorshorts and contactsbefore performingelectricalteststo determinethenumberoftestpoints needed. Youmustuse apipelocatorto accomplishthis.Apipe or cablelocator isatwo-partelectricaldevicethat sends an electricsignaldownthe pipelineusingthetransmitter,and thendetectsthissignalthroughthe receiver tolocateelectricalshorts and contacts. Youmustuse conductivelocating,not inductivelocating,toperformthistask.

  22. Theobjective ofline locatingisthat, rather thanlocatingthe pipeline, youare searchingfor any metal objectsthat may contactthepipeline,aswellasanydielectricunionsthatarenot working. Asinthepreviousillustration,conductivelocatingonlyenergizes theline it isattached to, and/or themainline. Other foreignlinesarenotnormallypickedup. Thisislargelyduetothefact that electricity always followsthepathofleastresistance, and thatisnormallydownthemainline. Ifyoupick upaservicelineorother unknownline,andthesignal strengthortoneincreases,thenyouhavemostlikelyfoundanelectricalshortor contact. Repairor replacetheinsulator,or clearthe contact, Onceallcontactsorelectricalshortsarecleared,thenthenext step istoperform asimplecurrent requirementtest.

  23. Beginbylocatingasuitabletestlocationwithinthesectionto be tested. Suitable conditionsinclude ready accessto the pipeline at a meter or other abovegroundpiping; a metal structureforuseasatemporarygroundbed,suchasametal post, barricade, anode connectionor short sectionoffence. Connect theDCpositive postofa truck battery or other DC powersource toatemporary ground. ConnecttheDCnegative posttothepipeline.Thenperformpipe-to-soiltestingwithin thesection,recordingP/Spotentialsfound,andthelocation, etc. CPArea -- + DCpowersource TemporaryGround

  24. ConductaP/Ssurvey: Onceyouhaveclearedallcontactsandelectricalinsulatorshortsandyou havesetupthesimplecurrentrequirementtest,takeP/Sreadings throughoutyouraffectedarea. Ifthe P/Stestingindicatesthattheentiresectionnowmeetstheselectedcriterion,then youmayonlyneedonetestpointwithinthesection,however, asintheprevioussituation,werecommendyouestablishaminimumoftwo teststationswithineachsection. IfP/Stestsindicateonlyaportionofthesectionnowmeetstheselected criterion,then youmustrelocateyourDCpowersourcetothe unaffectedarea,andreapplycurrent,retesting P/Sonceagain,untilyouhaveestablishedallteststationinthesection. CPArea UNKNOWN INSULATOR UNKNOWN --INSULATOR + DCpowersource TemporaryGround

  25. Atestpointisany abovegroundaccesspointwhere pipe-to-soiltestingmaybe performed.It canbe an isolationpoint,a meter,a regulatorset,etc. Ateststationmay be anassignedtestpointor a specifictestleadwireattachedtounderground piping,andisusedforannualtesting Youmust alwaysreadyourteststationsannually, butyoushouldreadrandom testpointsaswell, throughoutyourarea,just toverify thetest stationsyoucurrentlyhave are stillvalid.

  26. WeHavecovered: TheBasicCorrosionCell FormsofCorrosion ThreeToolstoFightCorrosion CathodicProtectionanditsLimitations CorrosionTroubleshooting CPToolsandEquipment EstablishingTestStations,andtheDifferenceBetweenTestPointsandTestStations

  27. Advanced CP Fundamentals

  28. AnyQuestions?

  29. Thank You! END

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