1、 P1:KpBNABK006-FM.tex nabk006/NACE Printer:Sheridan November8,2011 14:21GuidetoImprovingPipelineSafetybyCorrosionManagementNatural Gas and Hazardous LiquidTransmission Pipelines1440SouthCreekDriveHouston,Texas77084iP1:KpBNABK006-FM.tex nabk006/NACE Printer:Sheridan November8,2011 14:21C2011byNACEInt
2、ernationalLibraryofCongressCataloguinginPublicationDataHevle,Drew.Guidetoimprovingpipelinesafetybycorrosionmanagement/DrewHevle.1sted.p.cm.Includesbibliographicalreferencesandindex.ISBN1-57590-243-51.PetroleumpipelinesMaintenanceandrepair. 2.PetroleumpipelinesCorrosion.I.NACEInternational. II.Title.
3、TN879.58.H48 2011665.7prime440289dc23 2011040780ISBN:1-57590-243-5PrintedintheUnitedStatesofAmerica.Allrightsreserved.Thisbook,orpartsthereof,maynotbereproducedinanyformwithoutpermissionofthecopyrightowners.NeitherNACEInternational,itsofficers, directors,ormembersthereofacceptanyresponsibilityforthe
4、useofthemethodsandmaterialsdiscussedherein.Theinformationisadvisoryonlyandtheuseofthematerialsandmethodsissolelyattheriskoftheuser.NACEInternational1440SouthCreekDriveHouston,Texas77084http:/www.nace.orgiiP1:KpBNABK006-FM.tex nabk006/NACE Printer:Sheridan November8,2011 14:21ContentsForeword vPrefac
5、e vii1 Introduction 12 An Overview of Corrosion Concerns on Pipelines 33 Pipeline Corrosion Management 94 Corrosion Threat Assessment 135 Economic Considerations and Risk Evaluation 156 Mitigating Corrosion Risk 217 Integrity Assessments 398 Remediation 499 Program Effectiveness 59AppendixA:NetPrese
6、ntValueExplanationandExample 69AppendixB:EconomicsofCorrosion 73AppendixC:SelectAbovegroundCoatingStandards 81AppendixD:Termsand Definitions 89Index 93iiiP1:KpBNABK006-FM.tex nabk006/NACE Printer:Sheridan November8,2011 14:21ForewordPipelinesarethesafestformoftransportation,andacriticalpartofourcoun
7、trysinfrastructure.Pipelinesplayasignificant roleinthedeliveryofenergytoeveryone reading this and likely will for the span of each readers entire life-time.Pipelinesareplayinganincreasingroleinnontraditionalareas,includingalternative fuels such as biofuels and environmental activities such as carbo
8、nsequestration.Pipelinesareheretostayandaresafe.Thatbeingsaid,thereiscertainlyroomforimprovementinpipelinesafety.Ultimatelysocietydictatesthe level of public safety expected. Society balances the pressures of highersafety standards with the additional costs that those standards typically entailandle
9、tsindustryknowindirectlythroughtheirgovernmentrepresentatives,themedia,andincreasingly,directlythroughsocialmedia,litigation,andactivism.Oftenthegovernmentrespondstosocietysdemandforhighersafetystandardsbyissuingnewregulationsforminimumstandards.Sometimesthedriversforincreases in levels of safety ar
10、e technolog s becoming more affordable. Inie1984, New York State passed the first U.S. law requiring seat belt use in pas-sengercars.Seatbeltstodaysaveover11,000liveseveryyearintheU.S.alone.Seat belts evolved into passive restraints including airbags, anti-lock brakes,stability control systems, and
11、many other safety systems. Today most of uscantevenimagineatimewhendrivingwithoutsecuringourchildreninchildsafetyseatswascommonpractice.PipelinesafetyintheUnitedStateshasevolvedinaformofpunctuatedequilibrium. The stasis has been broken up by rare and rapid events driven(forthemostpart)bypipelinefail
12、ureincidents.CongresscreatedtheOffice ofPipelineSafety(OPS)in1968tooverseeandimplementpipelinesafetyregu-lations.The first statuteregulatingpipelinesafetywastheNaturalGasPipelineSafetyActof1968,andCongresslateraddedliquidpipelinestothestatuteinvP1:KpBNABK006-FM.tex nabk006/NACE Printer:Sheridan Nove
13、mber8,2011 14:21vi FOREWORDthePipelineSafetyActof1979.Thesetwoeventswerelargelydrivenbyanatu-ralgasexplosionin1965inNatchitoches,Louisiana,thatkilled17people.Thecauseofthefailurewasstresscorrosioncracking,afailuremechanismthathadnotbeenattributedtopipelinefailuresbeforethisincident.NACEInternational
14、played a part by developing and publishing its first standard, SP0169 (knownas RP0169 at that time), “Control of External Corrosion on Underground orSubmergedMetallicPipingSystems,”thatthecorrosioncontrolportionsofthenew Pipeline Safety Regulations were in part based on. More recent pipelinefailures
15、suchasthoseinBellingham,Washington,andCarlsbad,NewMexico,drovethePipelineSafetyImprovementActof2002,andrecentfailuresintheGulf of Mexico, in Marshall, Michigan, and in San Bruno, California, willcertainlymandatemorechangestopipelinesafetyregulationsandstandards.Why do pipeline failures generate such
16、 notoriety? Motor vehicle acci-dentskillmorethan45,000peopleperyearintheU.S.,butafatalcarcrashisntnational news like a fatality caused by a pipeline failure. Incidents related topower lines are much less notorious, and typically around 100 people in theU.S. are killed every year, whereas many fewer
17、people are killed in pipelineincidents. One reason is the record of success that pipeline safety has had todate similar to the affliction of the airline industry, where the expectation of, safetyissohighthatanyincidentatallbecomesnewsworthy.Anotherreasonmaybethatpowerlinesareahazardthatcanbeseenandu
18、nderstood,butmanypeoplearenotawareoftheburiedpipelinesnearthem.Much of the low-hanging fruit of pipeline safety has already beenplucked.Thereisalwaysroomforimprovement,buttherearenoeasyanswers,and no paradigm-shifting technologies on the immediate horizon. Improve-mentsinpipelinesafetywillhavetobema
19、debysmallimprovementsinalargenumberofareas.Thesetypesofimprovementslendthemselvestocomprehen-siveprograms,toensurethatoptimumdecisionsaremadeateachstageofthepipelineslife.PipelineCorrosionManagementaspresentedinthisdocumentisintendedtoprovideacomprehensiveprocessforensuringthateachdecisionrelated to
20、 managing corrosion on pipelines is fully considered. Pipelines areplaying an increasing role in our energy infrastructure, societys expectationsforpublicsafetyareeverincreasing,andcontinuousimprovementinmanagingthreatstopipelineintegritysuchascorrosionisessential.DrewHevleManager,CorrosionControlEl
21、PasoCorporationTG370ChairP1:KpBNABK006-FM.tex nabk006/NACE Printer:Sheridan November8,2011 14:21PrefaceConsidering the investment that owners make to build, maintain, and op-erate carbon steel onshore transmission pipelines, hereinafter referred to as“pipelines,”aswellastheriskandhazardsofapipelinef
22、ailure,itisimperativethatownersmanagethreatstopipelineintegrity.Aprincipalthreattopipelineintegrityiscorrosion.Transmissionpipelinesareprimarilyconstructedofcar-bonsteel,andcorrosionisatime-dependentthreatthatcausestheintegrityoftransmission pipelines to deteriorate if left unchecked. To maintain pi
23、pelineintegrity,aconcerteddesign,maintenance,andrepairprogramaddressingcor-rosionthreatsshouldbeimplemented.Theprimarygoalofthisguideistoprovidepipelineindustrymanagersand nontechnical personnel with an understanding of the basic issues andrequirementsformanagingcorrosionthreatstoonshoretransmission
24、pipelines.Itisunderstoodthatmostownershaveintegritymanagementprogramsinplacethat deal at some level with corrosion threats, and this guide is not intendedto replace these programs but to supplement those programs by providing afoundationalunderstandingofthefollowingconcepts:a114Basiccorrosionthreats
25、totransmissionpipelines,a114Risksposedbycorrosionthreats,a114Corrosionmitigationstrategies,a114Assessmentmethodologies,a114Identifyingandimplementingremediationactivities,anda114Methodsforevaluatingtheeffectivenessofaprogram.This guide is not intended to provide step-by-step instructions for managin
26、gpipeline corrosion; instead it outlines and identifies the essential componentsofaPipelineCorrosionManagementProgramandpresentsconsiderationsanddecision-making tools for developing and implementing a program. OwnersviiP1:KpBNABK006-FM.tex nabk006/NACE Printer:Sheridan November8,2011 14:21viii PREFA
27、CEcan develop their own programs based on their needs and can leverage thisguide,andcorrespondingreferences,asavailableresources.This guide has been prepared by Task Group 370, “Pipeline CorrosionManagement,” which is administered by Specific Technology Group (STG)35,“Pipelines,Tanks,andUndergroundS
28、ystems.”ThisguideispublishedbyNACEundertheauspicesofSTG35.P1:KpBNABK006-01.tex nabk006/NACE Printer:Sheridan November11,2011 14:6SECTION 1IntroductionWith origins dating back to approximately 1,000 B.C. (with the Phoeniciansfirst using a form of pipeline to transport water), pipelines have become on
29、eofthemostreliable,cost-effective,andsafestmodesoftransportingvitalcom-modities. Today, an elaborate network of pipelines can be found in nearlyeverydevelopedcountryaroundtheworld,withmorethan1.35millionmiles(2.17millionkm)ofoilandgaspipelinesworldwide.Thisvastnetworkhelpsdelivermorethan50%oftheworl
30、dsenergysupply.1Ensuringtheintegrityofthis infrastructure is paramount to delivering this critical energy source to itsvarioususersandthecommunitiesthatdependonthem.Pipelinesarerecognizedasbeingbyfarthesafestmodeoftransportingnatural gas and hazardous liquids, with fatalities resulting from accident
31、s onpipelines occurring much less often than accidents caused by transportationof goods by truck or barge. Fires or explosions are 35 times more likely perbarrel of oil transported by vehicle than when oil is transported by pipeline.2However,despitebeingoneofthesafestmodesoftransportation,pipelinesa
32、resubjecttoavarietyofthreatsandaccidentsthatcanresultinpropertydamage,injury, loss of life, or environmental damage. Corrosion remains a constantthreat to the integrity of pipelines, accounting for over 20% of all significanttransmissionincidentsintheU.S.3Corrosion attacks the steel walls of a pipel
33、ine, reducing its capacityto retain pressure. If corrosion is left unchecked, the resulting failure of thepipe wall can rapidly release oil or gas into the environment, causing fire andenvironmentaldamage.Figure1showsapipelinefailurecausedbycorrosion.This guide presents a defined process for the man
34、agement of corrosionspecific topipelinescarryingnaturalgasandhazardousliquids.Tohelp define1P1:KpBNABK006-01.tex nabk006/NACE Printer:Sheridan November11,2011 14:62 GUIDE TO IMPROVING PIPELINE SAFETY BY CORROSION MANAGEMENTFIGURE 1 Picture of a Pipeline Failure Caused by Corrosionthis corrosion mana
35、gement process and provide context for the process, thisguideprovidesabasicoverviewofthefollowingtopics:(1) A high-level overview of the corrosion threats to onshore gas and haz-ardousliquidtransmissionpipelines;(2) Methodologyandprocessworkflowalongwitheconomicconsiderationstoassistinthecorrosionma
36、nagementdecision-makingprocess;(3) Approachestoevaluatetherisksposedbycorrosionthreats;and(4) Key mitigation, assessment, and remediation strategies to preservepipelineintegrityandreducetheriskfromcorrosionthreats.P1:KpBNABK006-01.tex nabk006/NACE Printer:Sheridan November11,2011 14:6SECTION 2AnOver
37、viewofCorrosionConcernsonPipelinesPipelinesarethesafestandmosteconomicalwaytotransportvaluablegasandliquidcommoditiessuchasnaturalgas,crudeoil, refined products,andlique-fied natural gas. These commodities may be hazardous when unintentionallyreleased into the environment, with a potential for devas
38、tating impact to thepublic,totheoperatorsemployees,towildlife,property,andtotheoperatorsreputation.Takingstepstopreventsuchreleasesandimprovereliabilityisbotheconomicaland,inmostcountries,mandated.Specifically, the consequences of a corrosion failure on a transmissionpipelineinclude:a114Injuries and
39、 loss of life and the financial, political, and personal straincausedbythetragedies.TheU.S.gastransmissionandhazardousliquidspipelineindustryreportedatotalof10seriousincidents(thoseinvolvingdeathorhospitalization)causedbypipelineleaksorfailuresfrom1990through2009.a114Forliquidpipelinesenvironmentald
40、amageaccompaniedby significantenvironmental fines, cleanup costs, and public outrage from the releaseof hazardous substances into potable water sources and sensitive envi-ronmentalareas.a114Liabilityfordamagetorealproperty.ReportedincidentsintheU.S.from2005to2010totaled$2.3billioninpropertydamage.a1
41、14Damage to public relations. Large incidents are well publicized in themediaandofteninspireregulatoryand/orlegislativeresponsefromgov-ernmentbodies.Thishaseconomicconsequencesfortheentireindustryinadditiontotheoperatorresponsiblefortheincident.a114Loss of product and potential loss of revenue that
42、can result from thedisruptionofservice.3P1:KpBNABK006-01.tex nabk006/NACE Printer:Sheridan November11,2011 14:64 GUIDE TO IMPROVING PIPELINE SAFETY BY CORROSION MANAGEMENTFIGURE 2 Diagram of Corrosion Cell5Becauseoftheunacceptablenatureoftheseconsequences,a significant invest-ment has been made in t
43、he mitigation, prevention, and control of corrosionin an attempt to avoid costs associated with pipeline failures. For example,the cost of corrosion-related failures on U.S. pipelines constitutes less than10%ofexpenses,whilecapitalandoperatingexpendituresforthesepreventiveand control measures is mor
44、e than 90% of the total expenses, representingapproximately$4.9to$7.7billionannually.4A Basic Overview of CorrosionCorrosion is the deterioration of a material, usually a metal, resulting froma chemical or electrochemical reaction with its environment. Most forms ofcorrosionoccurthroughtheformationo
45、fanelectrochemicalcellconsistingofthefollowingfourelements:(1) Anode(2) Cathode(3) Electrolyte(4) Metallic(electronic)pathFigure 2 diagrams the corrosion process. Metallic ions (such as Fe2+)leavethemetalattheanodeandentertheelectrolyte.Ionscarrythepositivechargethroughtheelectrolytetothecathode,whi
46、letheelectronscreatedattheanodeP1:KpBNABK006-01.tex nabk006/NACE Printer:Sheridan November11,2011 14:6An Overview of Corrosion Concerns on Pipelines 5travel through the metallic path to the cathode. The reaction at the cathodecompletesthecircuit.Metallossofthematerialoccursattheanode,asaresultofions
47、leavingthemetal.The anode and cathode are defined by a difference in electrical po-tential. This can be caused by local differences in the electrolyte, mi-croscopic variations in metal structure, different types of metals beingjoined together, an external source of imposed current (rectifier), or ot
48、hersources of electrical energy. This diversity leads to a wide variety of cor-rosion phenomena. Common corrosion mechanisms relevant to transmissionpipelines are covered below; for a brief description of other types of corro-sion, visit http:/events.nace.org/library/articles/corrosion101.asp.5Corro
49、siononpipelinesisgenerallycategorizedasexternalcorrosion,internalcorrosion,orenvironmentallyassistedcracking(EAC).External CorrosionEven relatively dry soils may contain enough moisture to serve as the elec-trolyteinacorrosioncell.Externalcorrosionofburiedpipelinesis influencedby a number of factors such as external coating condition, ion concentra-tions in the soil, soil particle size, soil moisture content, proximity to otherburied structures, stray direct current (DC), and even induced alternati
