ProcediaEngineering84(2014)12–221877-7058©2014TheAuthors.PublishedbyElsevierLtd.ThisisanopenaccessarticleundertheCCBY-NC-NDlicense(http://creativecommons.org/licenses/by-nc-nd/3.0/).Peer-reviewunderresponsibilityofscientificcommitteeofBeijingInstituteofTechnologydoi:10.1016/j.proeng.2014.10.405ScienceDirectAvailableonlineatwww.sciencedirect.com“2014ISSST”,2014InternationalSymposiumonSafetyScienceandTechnologyLayerofProtectionAnalysisRonaldJ.WILLEYDepartmentofChemicalEngineering,NortheasternUniversity,Boston,Mass.,02115,USAAbstractAprocesshazardanalysis(PHA),suchasaHazardandOperabilityStudy(HAZOP),isausefultoolinidentifyingpotentialhazardscenarios;however,aPHAcanonlygiveaqualitativeindicationofwhethersufficientsafeguardsexisttomitigatethehazards.LayerofProtectionAnalysis(LOPA)isariskmanagementtechniquecommonlyusedinthechemicalprocessindustrythatcanprovideamoredetailed,semi-quantitativeassessmentoftherisksandlayersofprotectionassociatedwithhazardscenarios.LOPAallowsthesafetyreviewteamanopportunitytodiscoverweaknessesandstrengthsinthesafetysystemsusedtoprotectemployees,theplant,andthepublic.LOPAisameanstoidentifythescenariosthatpresentthemostsignificantriskanddetermineiftheconsequencescouldbereducedbytheapplicationofinherentlysaferdesignprinciples.LOPAcanalsobeusedtoidentifytheneedforsafetyinstrumentedsystems(SIS)orotherprotectionlayerstoimproveprocesssafety.Thispaperprovidesabriefoverviewofthetechniqueandisintendedforanoviceinterestedinthebasicprinciplesinvolved.©2014TheAuthors.PublishedbyElsevierLtd.Peer-reviewunderresponsibilityofscientificcommitteeofBeijingInstituteofTechnology.Keywords:safetymanagement;LOPA;SISNomenclatureAIChEAmericanInstituteofChemicalEngineering,120WallSt.,Fl23,NewYork,NY10005-4020CCPSCenterforChemicalProcessSafety,associatedwithAIChE.ESDemergencyshutdownfiCthefrequencyoftheconsequence,yr-1orhr-1IEFinitiatingeventfrequency,yr-1orhr-1IPLindependentprotectionlayerLOPAlayerofprotectionanalysisPFDaverageprobabilityoffailuretoperformupondemand(usedinlowdemandmode)PFHaverageprobabilityofdangerousfailuresperhour(usedinahighdemandmode)RRFriskreductionfactor;RRFisthereciprocalofPFDSIFsafetyinstrumentedfunction©2014TheAuthors.PublishedbyElsevierLtd.ThisisanopenaccessarticleundertheCCBY-NC-NDlicense(http://creativecommons.org/licenses/by-nc-nd/3.0/).Peer-reviewunderresponsibilityofscientificcommitteeofBeijingInstituteofTechnology13RonaldJ.Willey/ProcediaEngineering84(2014)12–22SILsafetyinstrumentlevelSISsafetyinstrumentedsystem1.IntroductionAdaptationofLayerofProtectionAnalysis(LOPA)beganinthechemicalprocessindustryinthelate1990s.ArthurDowell[1,2]andWilliamBridges[3],amongothers,beganimplementingthetechniqueintheircompaniesandconsultanciesasamethodthatcapturesthemainconceptsofindependentprotectivesafetysystems,withoutrequiringahighdegreeofquantitativeanalysis.AsthemethodbecamemorewidelyusedintheUnitedStatesandEurope,guidelinesbegantobeissuedbytheAIChECenterofChemicalProcessSafety(CCPS)[4].OtherinternationalagenciesandcodessuchastheInternationalElectrotechnicalCommission(IEC)[5,6]andInternationalSocietyofAutomation(ISA)[7]begantoreferenceLOPAasamethodfordeterminingtherequiredsafetyintegritylevel(SIL)forSafetyInstrumentedSystems(SIS).ThispaperhighlightsthepracticeofLOPA.Itisdirectedtothenovicewhomaywishtoapplyalayerofprotectionanalysistoafacilityandwould...
优质VIP
