20140129-chastainw-advancesinlayerofprotectionanalysis.pdfVIP专享VIP免费原创优质

WayneChastain,P.E.EastmanChemicalCompanyAdvancesinLayerofProtectionAnalysisAgendaOverviewofLayerofProtectionAnalysisGuidelinesforInitiatingEventsandIndependentProtectionLayersforLayerofProtectionAnalysisGuidelinesforEnablingConditionsandConditionalModifiersforLayerofProtectionAnalysisPathForward–EvergreenLOPADatabaseLayerofProtectionAnalysisSimplifiedformofquantitativeriskassessmentUsesorderofmagnitudecategoriesfor:ConsequenceseverityInitiatingeventfrequencyLikelihoodoffailureofIndependentProtectionLayers(IPLs)ProvidesanumericalindicationofadequacyofprotectivesystemsQuantitativeRiskAnalysisQRAisasuiteoftechniquesforbothconsequenceandfrequencyanalysisQRAtypicallyinvolvesevaluationofindividualriskand/orsocietalriskfromabroadrangeofeventsataplantsiteLayerofProtectionAnalysisIntroducedin2001SimplifiedSingleCause–ConsequenceAnalysisOrderofMagnitudeStrictRulesofIndependenceHowisLOPAused?ProcessHazardAnalysisEvaluationofadequacySafetyInstrumentedSystemsMostpopularmeansofdeterminingtheSafetyIntegrityLevelReliefDeviceDesignMitigationofreliefcasesLOPAProcessA•IdentifytheeventtobeanalyzedB•Determinetheconsequence•SelecttheriskcriteriaC•DeterminetheInitiatingEvent•SelecttheappropriateinitiatingeventfrequencyD•DetermineanyEnablingConditions•SelecttheappropriateprobabilityfortheenablingconditionE•DeterminetheIndependentProtectionLayers•SelecttheappropriateprobabilityoffailureondemandforeachIPLF•DetermineConditionalModifiers•SelecttheappropriateprobabilityforeachconditionalmodifierG•Calculateafrequencyofoccurrencefortheeventbasedontheinitiatingeventfrequency,theenablingevent,thePFDofeachIPL,andtheconditionalmodifiersH•ComparethecalculatedfrequencytotheriskcriteriatodetermineadditionalriskreductionrequiredSwissCheeseModelLOPAProcessDeterminetheConsequenceTheconsequenceisbasedontheimpactoftheeventConsequenceisusedtodeterminetheriskcriteriaLossofprimarycontainmentUltimateconsequencesLifesafetyEnvironmentalimpactBusinessimpactInitiatingEventsSeveralinitiatingeventsmayleadtotheconsequenceofinterestEachshouldbeevaluatedwithanindependentLOPAStandardvaluesareprovidedfortheinitiatingeventfrequenciesformostcommonfailures,forexample:BPCS(DCScontrols)loopfailuresOperatorerrorsTuberupturesLossofcoolingIndependentProtectionLayersIPLshavetomeetthreebasiccriteriaIndependentEffectiveAuditableStandardvaluesareusedfortheprobabilityoffailureondemand(PFD)forIPLsConditionalModifiersProbabilityofIgnitionProbabilityofPersonnelPresenceProbabilityofInjuryNottypicallyusediflossofprimarycontainmentistheendpointCalculatedEventFrequencyTheproductoftheinitiatingeventfrequencyandtheprobabilitiesoftheenablingcondition,theindependentprotectionlayers,andanyconditionalmodifiersprovidesthecalculatedeventfrequencyThecalculatedeventfrequencyisthencomparedtotheriskcriteriatodeterminethelevelofriskandtherecommendedreliabilityforadditionalcontrolstoreducetheriskCalculatedEventFrequency𝐸𝐸=𝐸𝐼𝐼×𝑃𝐼𝐸×�𝐼𝑃𝐼𝑃𝑃𝑃×�𝐶𝐶𝑃EventFrequencyInitiatingEventFrequencyEnablingConditionProbabilityProductofPFDsofIPLsProductofConditionalModifierProbabilitiesExampleLOPAFreq.orProb.RiskDescriptionScenarioExcessiveSteamFlowtoDistillationColumnResultsinOverpressure,Failure,andSevereInjuryConsequence10-5Singlesevereinjuryonthe...