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AGuidetoHazard IdentificationMethods
SecondEdition
FrankCrawley
Elsevier
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Notices
Knowledgeandbestpracticeinthisfieldareconstantlychanging.Asnewresearchandexperiencebroadenour understanding,changesinresearchmethods,professionalpractices,ormedicaltreatmentmaybecome necessary.
Practitionersandresearchersmustalwaysrelyontheirownexperienceandknowledgeinevaluatingandusing anyinformation,methods,compounds,orexperimentsdescribedherein.Inusingsuchinformationormethods theyshouldbemindfuloftheirownsafetyandthesafetyofothers,includingpartiesforwhomtheyhavea professionalresponsibility.
Tothefullestextentofthelaw,neitherthePublishernortheauthors,contributors,oreditors,assumeanyliability foranyinjuryand/ordamagetopersonsorpropertyasamatterofproductsliability,negligenceorotherwise,or fromanyuseoroperationofanymethods,products,instructions,orideascontainedinthematerialherein.
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Foreword
Iamdelightedtoprovideaforewordtothelatesteditionofthisimportantbook.Since thelasteditionwaspublished,Ihavebecomemuchmoreawareofhowimportantthe thinking,whichliesbehindthemethodologiesinhere,reallyisandhowmuchmorewe needtodotosharethisthinkingbeyondthedisciplinesofprocessandchemical engineering.
IChemE’shugelysuccessfulHazardsconferenceshavenowbecomearegularfeature aroundtheworldandin2020theUKwillcelebrateits30thHazardsconference.That meanswehaveahugebankofknowledge,whichhasbuiltupinourprofessionon howtoidentifyandmanageprocessrisksinasystematicway.Thetoolsandtechniques havebeenusedrepeatedlybygenerationsofchemicalengineers,theyhavebeen improveduponandnewapproacheshavealsobeenaddedtothetoolkitasresultofinnovativeideasandlessonswehavelearned.Itisgreattoseethisbookbeingupdatedto reflectthecurrentstateofknowledge.
Iamalsopleasedtoseetheauthorextendinghisreachtosharetheapplicabilityofthe methodologiesbeyondchemicalprocesssafety.In2017–18Iconductedanindependent reviewfortheUKGovernmentintoBuildingRegulationsandFireSafetyinhigh-risebuildingsfollowingthetragicfireatGrenfellTowerinWestLondon,whichclaimed72lives.In theprocessofgatheringevidenceforthisreview,itveryquicklybecameapparenttome thatmanyofthehabits,whicharesoingrainedinusaschemicalengineers,arenotso commoninotherengineeringdisciplines.
Whilstourfocushasbeenonhowtodesignandoperatechemicalprocessessafely,we havebeendevelopingmethods,whichcanequallybeappliedtomanyotherdynamicand complexsystems—includingmultiple-occupancyhigh-risebuildings.Systemdesignand managementofchangethroughoutthelifecyclearejustasimportantintheseareasasin chemicalprocessesandtheconsequencesoffailuretotakethatdisciplinedapproachcan becatastrophic.
Wemustensurethatchemicalengineerstodaymaintaintheirfocusonandcompetenceinprocessandsystemsafety,butwemustdomorethanthat.Wemustpassthat knowledgeontofuturegenerationsofchemicalengineersthroughbooks,conferences, andothermeansofcommunicationandeducationifitistotrulybepartofwhowe areandwhatwedotodeliverinherentlysaferprocesses.Wemustalsotakeourknowledge
tootherengineeringdisciplinesandshareitfreelywiththem.Wehaveanimportantjobto do—andahugeopportunitytomakeadifference—inhelpingotherstoseethevalueand thebenefitsoflookingatsystemsandprocessesthroughthelensesofhazardidentificationandriskreduction.
Ihopethisbookistrulywidelyread.
DameJudithHackitt
Acknowledgements
Thiseditionbuildsuponandextendsthefirsteditionpublishedin2003,whichreceived contributionsandsupportfrommanyindividualsandcompanies,whichwereacknowledgedtherein.OnceagainIhavereceivedsuggestions,reviewsofmydraftsandgeneral assistancefrommanypresentandformercolleagues.Inparticular,Iwishtoexpress thankstoRichardGowland,KenFirst,BrianTyler.
However,thefinalselectionofmaterialanditspresentationistheresponsibilityofthe authoralone.
Theauthorwishestothankthefollowingforpermissiontocopyphotosandtext:
• Picturesin Chapter15 suppliedbycourtesyofDNVGL(SpadeadamResearch& Testing).
• IChemEforthere-useofvarioustextsfromtheFirsteditionanddrawingsasnoted.
• DSScottforthepermissiontocopytheRiskCube.
Disclaimer
Theauthorandcollaboratorshavewrittenthisguideingoodfaithanddonotacceptany legalresponsibilityformisuseormisinterpretationofthetext. Itisaguidetouseandnotthedefinitivedocument.Theresponsibilityfortheselection andaccuracyanddetailofanystudylieswiththeuserorathirdpartywhomightcarryout theworkontheirbehalf.Themethodsshouldalwaysbeselectedwithduethoughttothe needandthefinaloutcomeofthestudy.Theuserorthirdpartyshouldensurethatthey havereceivedadequatetrainingandexperienceintheiruse.
Acronymsandabbreviations
ActualMPPD ActualMaximumProbablePropertyDamage
AIChemE AmericanInstituteofChemicalEngineers
ACOP ApprovedCodeofPractice
ALARP aslowasreasonablypracticable
ACMH AdvisoryCommitteeonMajorHazards
BI businessinterruption
BoD BasisofDesign
CEI DowChemicalExposureIndex
CHA ChemicalHazardAnalysis
CCF CommonCauseFailure
CMF CommonModeFailure
CIMAH ControlofIndustrialMajorHazards
COMAH ControlofMajorAccidentHazards
COSHH ControlofSubstancesHazardoustoHealthRegulations2002,amendment2003
DIERS DesignInstituteforEmergencyReliefSystems—AIChE
ERPG EmergencyResponsePlanningGuideline
ESD EmergencyShutdown(system)
EPSC EuropeanProcessSafetyCentre
ETA eventtreeanalysis
F&EI DowFireandExplosionIndex
FDT fractionaldeadtime
FEED Front-EndEngineeringDesign
FTA faulttreeanalysis
FME(C)A failuremodeandeffect(criticality)analysis
HASWA HealthandSafetyatWorkAct1974
HAZID hazardidentification(method)
HAZOP hazardandoperability(study)
HIPS High-IntegrityProtectionSystem
HS hazardstudy(0–7in Chapter3)
HSE HealthandSafetyExecutive
IChemE InstitutionofChemicalEngineers
IPC IntegratedPollutionControl
IPL IndependentProtectionLayer
IPPC IntegratedPollutionandPreventionControl
LFL lowerflammablelimit(sometimesalsoexplosivelimit)
LOPA LayerofProtectionAnalysis
MAPP MajorAccidentPreventionPolicy
MF MaterialFactor
MoC ManagementofChange
MPDO MaximumProbableDaysOutage
MPPD MaximumProbablePropertyDamage
NISHH NotificationofInstallationsHandlingHazardousSubstances(NIHSS)Regulations1982
NPSH NetPositiveSuctionHead
PFD ProbabilityofFailureonDemand(akaProbabilityofFailuretoDanger)
PHA processhazardanalysis
PHR processhazardreview
P&ID pipingandinstrumentationdiagram
PPE personalprotectionequipment
PtW PermittoWork
RR relativeranking
RAST riskassessmentscreeningtool
RIDDOR ReportingofInjuries,DiseasesandDangerousOccurrencesRegulations2013
SEP SurfaceEmissivePower
SHE Safety,Health&Environment
SIL SafetyIntegrityLevel
SIS SafetyInstrumented(interlock)System
SMS safetymanagementsystems
UFL upperflammablelimit(sometimesalsoexplosivelimit)
VCE vapourcloudexplosion
SIunits
M mega m milli
p pico
F Farads
J Joules
Pa Pascals
W Watts
Regulatoryframework
1.1Overview
Societyissubjecttorulesandthereisnodifferenceforindustry.Thischaptergivesabrief reviewoftherulesorRegulationsbywhichtheChemicalIndustrymustoperateandlinks theseintothevariouschapterswithinthisMonograph.ItconcentratesontheUnited Kingdom,workingwithintheEuropeanUnionsystem.
Therearemanyaccountscoveringtherulesofdifferentnon-EuropeanUniondifferent NationsorStates.Thesemustbeunderstoodfullyandfollowed.Therefore,eachnationor statewithinanationmustusetherulesappropriatetothatnationorstate.
1.2Background
ThedevelopmentofchemicalandpetrochemicalmanufacturinginthepostSecondWorld Warerahasledtoaglobalexpansionofproductionandstoragefacilities.Forexample,the sizeofolefinplantsbetween1948and1968wasdoublingevery7or8years,whilethesite footprinthadhardlychanged.Newprocessessuchasthedirectoxidationofethylene withpureoxygenweredevelopedandmanynovelprocesses,particularlyinthepharmaceuticalindustry,werebroughton-line.Thesefacilitiesintroducednewhazardsinto communitiesandneighbourhoodswhichrequiredregulation.
Ingeneralthehistoriclegalframeworkwasreactive,notanticipative,althoughnewer frameworkshavetendedtobemoreanticipative.
Thefirst‘SafetyActs’gobackover150yearswiththeregulationofchemicalprocess safetybecomingmoreestablishedsincethe1970s.Variousreasonsexistforthepromulgationofthedifferentregulationswithoneofthemaininitiatorsofnewregulations
orchangesinexistingregulationsbeingtheoccurrenceofmajoraccidentswith seriousconsequenceseitherforthesafetyofemployees,theneighbourhoodorthe environment.
WithinUnitedKingdomtherearesomedifferencesofapproachtoregulationwithin thecomponentcountriesoftheUnitedKingdomasaresultofancientActspassedmany yearsago [1,2,3,4].ThusintheUnitedKingdomthereisEnvironmentalAgency,whilstin ScotlandthereistheScottishEnvironmentalProtectionAgency(SEPA).
Itisself-evidentthattheregulationsrequiretobepolicedrequiringaRegulatoror CompetentAuthoritywithmeansofenforcementsuppliedbyoverarchingActs.
BackgroundinUnitedKingdom
TheregulationofmajoraccidenthazardswithintheUnitedKingdomhasitsrootswithin thereportoftheRobens’Committeein1972 [5].Thisidentifiedthat‘majorhazards’associatedwithtechnologypresentaparticularproblem,andrecommendedcomprehensive provisionstodealwithtoxic,explosiveandflammablesubstancesbeadopted.Tothisend thecreationofamajorhazardsbranchwithinthenewinspectorate(i.e.Healthand SafetyExecutive)wasrecommended,aswastheestablishmentofaStandingAdvisory CommitteeonMajorHazards(ACMH).TheACMHbeinggiventheremittoidentifytypes ofinstallationswhichhavethepotentialtoposeamajorhazardandtoadviceonmeasures ofcontrol.OneoftherecommendationsofACMH(ACMHIII)was‘LandUsePlanning’. HoweverbeforetheresultingregulationfromtheRobens’Report,theHealthandSafety atWorkAct [6] couldtakeeffect,oneoftheworstaccidentsinBritishchemicalprocessing history,theexplosionandfireatFlixborough,occurredon1June1974.
ThesequenceofmajorRegulationswithintheUnitedKingdomunderHASWAhas been:
• 1978ThepublicationoftheHazardousInstallations(NotificationandSurvey Regulations) [7] asaconsultativedocumentinlinewiththeHealthandSafety Commission’sdutytoconsultunderthetermsoftheHASAWAct.
• 1983NotificationofInstallationsHandlingHazardousSubstances(NIHSS) Regulations1982 [8].
• 1984RIDDORRegulations(ReportingofInjuries,DeathsandDangerousOccurrences Regulations).
• 1984ControlofIndustrialMajorAccidentHazards(CIMAH)Regulations(1984) [9] implementingEECDirective82/501/EEC.
InmanywaystheUnitedKingdomhasledtheEuropeanUnioninProcessSafetyanduses astructureatfourlevels:
TheAct
TheRegulation—orStatutoryInstrument(empoweredbytheAct)
TheApprovedCodeofPractice(whatisexpected) GuidanceNotes
EvolutionEuropeanUnion
FollowinganaccidentatachemicalfacilityinItalyacloudofca.10tonnesofchemicals, includinganestimated1–2kgTCDD(dioxane),wasreleasedovertheneighbouringtown, Seveso.ThenameofthetownhasbeenadoptedforthemajorEuropeanUnionregulations.Hence‘SevesoDirective1’andtwoupdatesfollowingfurtherincidents.Theconcept oftwotiersofapplicationwaskeptinbothSevesoIIandthecurrentSevesoIIIDirective. MemberStateswererequiredtoensurethatthelower-tierestablishmentsprovide notificationtothecompetentauthorities,fulfilthegeneraldutyofsafeoperationto preventmajoraccidentsandthattheoperatorestablishedamajoraccidentprevention policy(MAPP).TheMAPPwasthebasisforthemanagementofsafetyatSevesoIII establishments.
ThedangeroussubstancesintheSevesoIIDirectivewereprimarilycoveredinten genericcategoriesrelatedtoacutetoxic,flammable,explosiveorenvironmentalhazard properties.InadditiontheCommissionproposedaverymuchshorterlistofnamedsubstancesthanincludedintheoriginalSevesoDirective.Thesearegenerallysubstances, whichhaveaverywidespreaduseinlargequantities,aresubstancesofparticularconcern orareofparticulareconomicimportancewhereaverylowthresholdlevelwouldcausean extremelylargenumberofsitestobecoveredbytheDirective.
1.3FeaturesofSevesoIIIDirective
TheSevesoIIIDirective [10] placesrequirementsontheMemberStatesoftheEuropean Uniontosetnationalregulationsforoperatorsandforthecompetentauthoritieswhich enforcethenationallegislationandimplementtherequirementsoftheDirective.The requirementsmaybedescribedasfollows:
Scopeanddefinitions:ApplicationoftheDirectiveisto‘establishments’inwhich sufficientquantitiesofdangeroussubstancesarepresentormaybepresent.This mayinvolveaddingthevariouscomponents inamultiprocesssite.Activities,which areexcludedfromthescope,arethosecoveringmilitaryinstallationsandfacilities; hazardsduetoionisingradiation;thetransportationofdangerouschemicalsandtheir immediateactivities,marshallingyards,docks,wharves;wastelandfillsites(excluding tailingspondsanddams);mineralextractionactivities;offshoremineralandhydrocarbonextraction.
Generalrequirements:Operatorsaretoberequiredtoshowthattheyhavetakenall measuresnecessarytopreventtheoccurrenceofmajoraccidentsandtolimittheireffects tomanandtheenvironment.Further,anoperatorshouldbeabletoprovetothecompetentauthorities,atanytime,thatthesemeasureshavebeentaken.(See Chapters3–5, 7, 15, 16, 17 and 19.)
Notification :Operatorsaretoberequiredtonotifythecompetentauthoritiesof theirexistence,thehazardoussubstancesi nvolved,theactivity,thepersonincharge oftheestablishment.Thisinformationistobeprovidedpriortocommencingthe
activityandwithanysignificantchange,incl udingclosureoftheestablishment(seethe ‘SafetyReport’later).
MajorAccidentPreventionPolicy(MAPP): Theoperatoristoberequiredtoprovidea writtendocumentsettingoutthepolicyforthepreventionofmajoraccidentsandto ensurethatitisproperlyimplementedandguaranteedahighlevelofprotectionfor manandtheenvironmentbyappropriatemeans,structuresandmanagementsystems. Thesemeanscanbereviewedorexaminedbythemethodsoutlinedin Chapters3–5 andinparticularTaskAnalysis(Chapter6).Audits(Chapter17)thengivesguidanceon examinationoftheseforweaknessesorsystematicdriftinstandard.
SafetyManagementSystem(SMS): TheoperatorisrequiredtoestablishaSafetyManagementSysteminaccordancewithappropriateAnnexoftheDirective.TheSMSshould beproportionatetothehazardsandrisksoftheactivitiesoftheestablishmentand adaptedtothecomplexityoftheestablishment’sorganisationalstructure.TheMajorAccidentPreventionPolicyisanintegratedelementoftheSMS.ThisgivestheSMSastructure similarinformtothatofenvironmentalmanagementsystemsaccordingtoISO14001or qualitymanagementsystemsaccordingtoISO9001.[ThisMonographdoesnotcover managementsystemsexplicitly,buttheyarepartoftheanalysisinHazardStudies (Chapter3),HAZOP(Chapter4),HAZID(Chapter5),TaskAnalysis(Chapter6),Risk Assessment(Chapter15)andVulnerability(Chapter16)].
SafetyReport: Theoperatorofanupper-tierestablishmentisrequiredtoproducea SafetyReport,whichisacoredocumentationoftechnical,organisationalandmanagementmeasurestoensurethesafeoperationoftheestablishment.TheSafetyReportis tohavethepurposesof:
(a) demonstratingthatamajor-accidentpreventionpolicyandasafetymanagement systemforimplementingithavebeenputintoeffectinaccordancewiththe informationsetoutinAnnexIII;
(b) demonstratingthatmajor-accidenthazardshavebeenidentifiedandthatthe necessarymeasureshavebeentakentopreventsuchaccidentsand/ortolimittheir consequencesformanandtheenvironment;
(c) demonstratingthatadequatesafetyandreliabilityhavebeenincorporatedintothe design,construction,operationandmaintenanceofanyinstallation,storagefacility, equipmentandinfrastructureconnectedwithitsoperationwhicharelinkedtomajoraccidenthazardsinsidetheestablishment;
(d) demonstratingthatinternalemergencyplanshavebeendrawnupandsupplying informationtoenabletheexternalplantobedrawnupinordertotakethenecessary measuresintheeventofamajoraccident;
(e) providingsufficientinformationtothecompetentauthoritiestoenabledecisionsto bemadeintermsofthesiteofnewactivitiesordevelopmentsaroundexisting establishments.
TheminimumcontentsoftheSafetyReportarelistedinAnnexIIoftheDirective.Itmust howevercontainanup-to-dateinventoryofdangeroussubstancesintheestablishment.
TheSafetyReportisnotadocument,whichisfinalisedinonego.Itshouldbea‘living document’.Thismeansthataregularreviewprocessshouldbeestablished,whichensures thatthatdescriptionswithintheSafetyReportarekeptuptodate.TheDirectiverequires thattheSafetyReportshouldbeamendedasnecessaryasaresultofalterations(material orsignificantchange)totheestablishmentastheresultof:
(a) newtechnicalknowledgefollowing‘nearmisses’ormajoraccidents.
(b) aregularreviewprocess,whichshouldtakeplaceatleasteveryfiveyears.[SeePHR (Chapter19)andotherreferencestorepeatingstudiesregularlysuchasHAZOP (Chapter4)].
(c) asignificantchangeintheprocessandinventory.
Inthecaseof‘TopTierProcesses’theSafetyCaseshouldberesubmittedevery5years.The factthatacompetentauthorityhasacceptedaSafetyReportdoesnotabsolveanoperator ofanyresponsibilityforthesafeoperationoftheestablishment,norisitastatementthat theestablishmentcannothaveamajoraccident.
TheSafetyReportistobesubmittedtotheCompetentAuthorityandthis,inturn,isto giveitsopiniononthereport,withinareasonabletime.Practicehasshownthatthismay rangefrom:‘acceptanceofthereportassubmitted’;through‘acceptancewithamendments’;to‘rejectionofthereport’.(‘Acceptedbutnotnecessarilyacceptablehasbeen quotedbytheRegulator’.)
On-siteandoff-siteemergencyplanning: Emergencyplanningisdividedbetween thoseactivitiestobecarriedoutbytheoperat or,on-site,andthoseactivitieswhichfall withintheresponsibilitiesoftheemergencyplanningauthorities,off-site.Themeasures shouldbeco-ordinated,whichrequiresthattheoperatorprovidestheemergencyplanningauthoritieswiththenecessaryinformationtocarryouttheexternalemergency planning.Theplansmustalsobedevelopedinconsultationwiththosewhomaybe potentiallyaffected.Thereforethedrawingupandtestingofinternalemergencyplans mustinvolvetheemployees,includinglong-t ermsubcontractors.Externalemergency plansshouldbedrawnupinconsultationwiththepublic.Theminimumcontentsof theemergencyplansaregivenintheappropriateAnnexoftheDirective.TheuseofRisk Assessment(Chapter15)andVulnerability(Chapter16)willassistinthedevelopmentof theseplans.
Informationtothepublic: TheDirectiverequiresthatMemberStatesensurethat informationisprovidedtothepublicandhe ldinapermanentlyaccessibleelectronic formabouteveryestablishment.MinimumcontentislistedintheappropriateAnnex oftheDirective.Thereisnostipulationastowheretheinformationistobeheld;thus, itispossiblefortheinformationtobeprovidedonasinglenationalportaloronthe internetsitesofestablishmentsorcorporati ons.Inadditionforupper-tierestablishmentsinformationonsafetymeasuresandtherequiredbehaviourintheeventofa majoraccidentistobesuppliedtothosewhomaybeaffected.Thatis,theinformation istobesuppliedtoallpersonsandtoallestablishmentsservingthepublicwithoutthem requestingit.ThepracticalapplicationofthisrequirementintheMemberStatesvaries
fromtheinformationbeingsuppliedbytheau thoritiestotheinformationbeingsuppliedbytheoperatoroftheestablishmentoragroupofestablishmentswhicharein closeproximity.Whicheverapproachischosen,thereneedstobeaclosecooperation betweentheoperatorsandtheauthorities.Thereneedstobeacleardefinitionofthe neighbourhood,whichistobeencompassedbytheinformationandalsohowtheneighbourhoodshouldbewarnedintheeventofanemergency.Itshouldbeclearwhetherthe operatorortheauthoritiestriggerthea larmsignalandhowthethirdpartiesshould respond.
Reportingofmajoraccidents: MemberStatesarerequiredtoensurethatintheevent ofamajoraccidenttheoperatornotifiestheauthoritiesassoonaspracticableandbythe mostappropriatemeans.Thenotificationshallcoverthecircumstancesoftheaccident, thedangeroussubstancesinvolved,thenecessarydataforassessingtheeffectsoftheaccidentandtheemergencymeasurestaken.Furthertheoperatorshallinformtheauthorities ofthemeasuresthatareenvisagedtodealwiththeeffectsoftheaccidentandtoprevent therecurrenceoftheaccident.Theinformationshallbeupdatedbytheoperatorinthe eventthatadditionalfactsorinformationbecomeavailable.
Thecompetentauthorityshallberequiredtoensurethaturgent,medium-orlongtermmeasuresaretakentodealwiththeaccident.Theauthorityshallcollectthenecessaryinformationforafullanalysisoftheaccident.Itshallalsoensurethattheoperator takesthenecessaryremedialmeasurestodealwiththeaccidentandmakerecommendationsonfuturepreventativemeasures.
Inspectionofestablishmentsbypublicauthorities: TheMemberStatesarerequired toensurethatthecompetentauthoritiesestablishaninspectionsystemtoassessthetechnical,organisationalandmanagementspecificaspectsofthesafetyoftheestablishment. Thisinvolvesassessingtherelevantdocumentationaswellascarryingoutanon-site inspectionoftheestablishment.TheDirectiverequiresthattheinspectionsofupper-tier establishmentsarecarriedoutannuallyunlessthecompetentauthorityhasestablisheda programmeofinspectionsbasedonasystematicappraisalofthemajoraccidenthazards oftheestablishment.Followingtheinspection,areportshallbepreparedandfollowedup withthemanagementoftheestablishment.
TheDirectivedoesnotmakespecificdemandsontheintensityoftheinspectionby thecompetentauthorities.Experienceshows thatlarge,complexestablishmentscannot beinspectedintheirentiretyinoneon-siteinspectionvisit.Inadditionitshouldbe recognisedthataninspectiondoesnotincreaseineffectivenesswithincreasinglength andthatgeneralimpressions,targetedinsp ectionsofindividualaspectstogetherwith spotchecksandinterviewsleadtothebestresults.Keyforasuccessfulon-sitevisitis goodpreparationbeforehand,togetherwithatransparentdocumentationofthose aspects,whichhavebeenassessedandthefindingsoftheinspection(see Chapter17).Theresultsneedtobefollowedupwiththemanagementoftheestablishmentandshouldincludeatimetableforthe implementationofthenecessarymeasures (see Chapter17).
Land-useplanning
RequirementsonmemberstatestoprovideinformationtotheCommission:Forthe CommissiontobeabletoenforcetheDirectiveaswellastobeabletofollowitsapplicationanddeveloptheregulationsinanappropriatemanner,itisdependentoninformation providedbytheMemberStates.TheMemberStatesarerequiredtoprovideinformation relatingtothefollowingaspects:
(a) theimplementationoftheDirectivewithinthenationallegalsystemsandstructures.
(b) a3-yearreportoftheimplementationoftheDirectiveaccordingtoaquestionnaire, whichisprovidedaccordingtoaprocedureonthestandardisingandrationalisingof reports.
(c) acatalogueoftheestablishmentsfallingundertheDirectivewithintheMemberState.
(d) areasonedlistoftheexceptionsfromtheprovisionofinformationwithintheSafety Report.
(e) informationonthosemajoraccidentswhichhaveoccurredintheMemberState.This informationistobeprovidedaccordingtoanagreedformatandismadepublic, exceptforthosedatawhicharedeclaredasconfidential,intheonlinedatabase ‘eMARS’.
Otherareas
ThereareclosesimilaritiesbetweenUnitedKingdomandEuropeanRegulationsin Canada,AustraliaandNewZealand.
Othernationshavetheirownrules,soitisessentialthattherulesofthatnation(or StateinUSA)arefollowedtothefull.
TheOffshoreOilandGasindustryhassomedifferentrules,includingthesecurityof theSafeHaven(TemporaryRefuge)againstfireandsmokeingressaswellasthemeans ofescapefromtheinstallationaswellasthesiteofafire.The‘totalrisk’mustalsoinclude helicoptertransitsfromtheheliporttotheinstallationaswellasshippingcollisionand structuralfailureoftheinstallation.Thesedonotapplyonshore.
Thehelicoptertransitispotentiallyasignificantelementinthetotalrisktooffshore employees.
Appendix
Furthermaterialmaybefoundat:
aicheme.org ‘RegulationsandResourcespage’. J.BessermanandR.A.Mentzer,Reviewofglobalsafetyregulations,J.LossPrev.Proc. Ind.50(2017)165–183. http://www.hse.gov.uk/pubns/hse49.pdf. https://www.hse.gov.uk/pubns/hsc13.pdf.
References
[1] ThePlanning(HazardousSubstances)Regulations2015,2015.SINo.627.
[2] TheTownandCountryPlanning(HazardousSubstances)(Scotland)Regulations2015,2015.SSINo 181.
[3] ThePlanning(HazardousSubstances)(Wales)Regulations2015,2015.No.1597(W.196).
[4] ThePlanning(HazardousSubstances)(No.2)Regulations(NorthernIreland),2015.SRofNI2015No. 344StatutoryInstruments(Regulations)OwnedandEnforcedbyHSE.
[5] L.Robens,SafetyandHealthatWork,ReportoftheCommittee1970-72,HMSOCmnd.5034,1972.
[6]HealthandSafetyatWorkAct1974.
[7]HazardousInstallations(NotificationandSurveyRegulations)Regulations1978.
[8]NotificationofInstallationsHandlingHazardousSubstances(NIHSS)Regulations1982.
[9]ControlofIndustrialMajorAccidentHazards(CIMAH)Regulations1984.
[10]Directive2012/18/EUoftheEuropeanParliamentandoftheCouncilof4July2012onthecontrolof major-accidenthazardsinvolvingdangeroussubstances,amendingandsubsequentlyrepealing CouncilDirective96/82/EC,Off.J.Eur.Union197(2012)1–37. http://data.europa.eu/eli/dir/ 2012/18/oj
AguidetoHazardIdentification Methods
Chapteroutline
2.1HazardIdentification
HazardIdentificationisfundamentaltothesafedesignandoperationofanysystem,beit aprocessplantoranyotherfacility.Thetoolsusedvaryaccordingtothesituationbutthey areallrigorous,systematicanddependtoagreaterorlesserextentontheknowledgeof teammembersthatwillusuallycontainsomeformofexpertise.
Thisbookprovidesaselectionguidethatattemptstointroduce,describeandillustrate themostcommonlyusedmethods,andthentodirectthereadertomoredetailedreferenceswherefullerguidancemaybefoundonthespecificmethod.Itdoesnotprovidea fulllistingofalloftheavailablemethod.Theselectioninthe1steditionwasbasedonan analysisofthemorecommonmethodsusedbyEPSCMembers:newandmoremodern methodshavebeenaddedinthisedition.Itshouldbenotedthattheauthorfoundthata generalmethodmighthavesomeverysmall,industry-specific,featuresorchangesand thenbeknownbyadifferentname.Thedescriptionsgivenhereforeachmethodare genericandnon-industryspecific,sothatthemethodscanbeusedbydifferentindustries withminor,casespecificvariations.Inthedescriptionsitwillbeseenthatamethodmay sometimesuseanadaptedpartofanothermethod.Thistooistobeexpectedasmost methodswillincludethebestpartsofother,triedandtestedmethods.Theusershould reviewthemethodsandchosetheonemostappropriatetothattask.
ThemethodsselectedbytheEPSCmembersincludesomethatareontheboundary betweenidentificationandassessment.Theseinclude:
• FaultTreeAnalysis(FTA)
• EventTreeAnalysis(ETA)
• FailureModesEffects(andCriticality)Analysis(FME(C)A)
Thesemethodscanbeusedbothanalyticallyandquantitatively.Inthefirstmodetheycan beusedasaninvestigativetool,butitisinthesecondmodethattheyhavemostuse.
Eachmethodisdescribedunderthefollowingheadings:
• Definition
• Description
• Resourcerequirements(bothpersonnelanddocumentation)
• Timing(againstthePHAtimeframe)
• Advantages,disadvantagesanduncertainties
• References
• Illustratedexample(ifneeded)
HazardIdentificationshouldberegardedasasetoftoolsthatareusedattheappropriate timeduringaparticularprojectdevelopment(Chapter3).Thetimingofuseisnotalways criticaland,otherthanpossiblyforHAZOPstudy,theremaybeseveralpointsinaproject whereamethodcanprofitablybeused.Alsoitshouldberecognisedthata‘project’could beamaintenancetask,amodificationoralargeconstructionproject.Theidentification methodscanbeconsideredforanyofthese,theonlydifferencesbeinginthedepth,the effortandtherecording.Whilecertainmethodshavemoreapplicationtotheprocess industry,fromwheretheyevolved,themethodscanbeofvalueinanytaskinanyEngineeringorSciencefield.Themethodsshouldalwaysbeselectedwithduethoughttothe needandthefinaloutcomeofthestudy.
Theappendicesinthisbookprovidethreeexamplesshowingwhichofthemethods anditisintendedthattheyshouldbeeasilyunderstood.Full,realexampleswouldbe muchmorecomplexanddetailedandcannotbeusedinanintroductorydocumentsuch asthis.Theyalsogiveamoredetailedillustrationoftheinterplayofthevariousmethods andshowhowtheycan,andoftendo,interacttoproducethebestresults.Whereworked examplesaregiveninthemethoddescriptionsinthemaintexttheyareintendedtohelp explainthedetailedworkingofthatmethod.
AlloftheillustrativeexamplesgiveninthisMonographaredeliberatelyrelativelysimple,requiringlittleornospecificpriorknowledgeandthereforeshouldbeeasilyunderstood.Full,realexampleswouldbemuchmorecomplexanddetailedandcannotbeused inanintroductorydocumentsuchasthis.
Table2.1 showstheusualtimingsforeachoftheselectedmethodsbasedonthestandardstagesofaproject.Asdescribedin Chapter4,anadditionaltwospecialisedstages, number0and7,havebeenincludedtotheoriginalsetof6.Inthetablethemostlikely timeofuseforamethodisshownbyanX:alesslikelytimeisshownby(X).Definitions oftheabbreviationsaregivenintheappropriatechapters.
NotethatHAZOPisshownasapossibilityatprojectstage2,astheremaybesome desiretocarryouta‘preliminary’HAZOPonapipingandinstrumentationdiagram (P&ID)asitisbeingdeveloped.
Noindexisprovidedforthisbookasastandardisedformathasbeenusedinthe descriptionofeachoftheselectedmethodsandthepartsofeachdescriptionarefully detailedonthecontendpages.
Table2.1 HazardIdentificationMethodandindicativeproject(lifecycle)phase(order ascontents).
Projectlifecyclestages,0–7(asidentifiedin Chapter3) Methodused01234567
HazardStudiesXXXXXXXX HAZOP(X)XX HAZIDXXXX TaskAnalysis(X)X(X)X LOPAXX(X)
RelativeRankingXX(X)(X) RiskAnalysisScreeningTool(RAST)XX(X)X CheckListsXXXXXXXX
Therearenowmany‘HazardIdentificationMethods’.Theoldesttwoareprobably ‘Checklists’and‘Whatif?’Thenextoldestisprobably‘HazardandOperabilityStudies’ (nowknownasHAZOP),whichwastrialrunin1968andevolvedfromMethodStudy.Since thennewmethodshaveevolved,somearevariationsonother,older,methodssuchthat thereisthepossibilityofconfusioninthemindsofpotentialusers.Thismonographisa selectionofthemorecommonlyusedmethodsgivingthestrengthsandweaknessesofeach andhow/whereitmightbeused.Eachhasanillustrativeexampleoftheuseinreality.Itis onlyaguideandisnotthedefinitivedocumentoneachmethodbutshouldgivesufficient informationforEngineersandScientiststobeabletochosewhichonemightbeappropriate inaspecificcaseandtobeabletoassessthedetailandqualityofanyworkcarriedoutbya secondpartystudy.Inlinewiththedisclaimeritistheresponsibilityofanypotentialuserto seektrainingandguidancefromatrainedpractitionerbeforeusinganyspecificmethod.
Thegeneralhierarchyofrisk-reducingmeasuresisasfollows:
• Prevention,
• Detection,
• Control,
• Mitigation,
• Emergencyresponse.
Itisnotpossibletowriteamonographsuchasthissoastocovereverytopicsoithashad tobeselectiveandleanstowards‘detection—atdesign’.Inthecaseofprevention,mitigationandemergencyresponsesomeguidanceisgivenunderRiskAssessment(Chapter15) andVulnerability(Chapter16).
Thereisonefinaltool,whichiscalledProcessHazardReview(Chapter19).Thisis carriedoutonanexistingprocessandexaminesthehistoryandexperienceoftheoperationsstaff.Itisnotusedinthedevelopmentofaprojectbutisusefulforanexisting process.
TaskAnalysis maybecarriedoutthroughoutaproject.Theareasshownareindicative. ItmaybeusedduringtheStudies2and3processtodesignthemaintenanceoftheequipmentandatStudy7tofacilitatedemolition.Itwillbeusedduringallphasesofoperation includingshutdownandstartup.
Audits canbecarriedoutonanyphaseofthedevelopmentoftheproject,buttheyare probablymoreusefulduringthesteady-stateoperationalphaseoftheprojectexamining thedriftofManagementSystemsfromrecognisedstandards.
Notethat HAZOP isshownasapossibilityatstagetwooftheSafetyStudies—Process HazardAnalysis,astheremaybesomedesiretocarryouta‘preliminary’HAZOPona P&IDasitisbeingdeveloped.
Groundrules
ItisatimelywarningthatmoreandmoreoftheHAZOP/HAZIDstudiesarecarriedoutby Facilitatorswhoare‘contracted’.Toooftentheyarechosenforparticularskillsandenter thestudytotallycold.Thescope,termsofreferenceandgroundrulesshouldbeagreed withtheclientpriortothestudy.
Therearecleargroundrulesbeforeexecutinganystudy.Theseare:
TheScope shouldcovertheboundariesofthestudy,includewhatistobedoneand whatistobeexcluded.Itshouldbethatresultofadialoguebetweentheclientandthe Facilitatorandshouldwhereappropriatecoverthe‘matrix’.Itshouldcoverwhoshould carryouttheactionsandwhethertheyshouldberankedinpriority.Thescopeshouldalso addresstheresponsibilitiesforrestudyparticularlyfollowingaHAZOPwheretheremay bematerialchangesinthedrawings.
TheTermsofReference shouldcoverthedeliverydateandwhereappropriatethereferencespoints,forexampleinanAuditagainstwhatshouldtheactionsbemeasured.
ReportingandWorksheets Itisimportantthatthereisastandardformofworksheetsor reports.Thiswillgreatlyassistintheauditingofanystudywheretheauditorwillknow whereandwhattolookforinthefinalreport.
Interlinking
ManyHazardIdentificationMethodscross-linkwithothersorhaveevolvedfromanother. Thiswillbemoreobviouswhenthelinksareshown.Thishasbeendrawnoutinthethree examplesinAppendices.
InadditionitshouldberecognisedthatsomeHazardIdentificationMethodsare appropriatetoaspecifictask.Thatmeansthatthecorrectmethodshouldbeusedso astooptimisetheuseofresourcesforthemaximumreturns.
Thesetopicsarecoveredinmoredetailinthechaptersindicated.
TheLegalStructure (Chapter1)isderivedfromhistoriceventsleadingtoActsorRegulationsandtheneedtocarryoutadetailedassessmentofasituation.
HazardStudies (Chapter3),alsoknownasProcessHazardAnalysis,evolvedinthelate 1960sfollowinganupsetonachemicalplantresultinginthereleaseofchlorine.Itisthe systematicanalysisofthedevelopmentofaprojectfrominceptiontodemolition.Ithasa structure,whichcanbeadaptedforuseinTaskAnalysis,writingaprocedure,orchecking thedevelopmentofaproject.WithinthiscouldbethemethodologiescalledHAZOP, HAZIDandAudits.
HAZOP (Chapter4)isastructuredanalysisofaP&ID.Itreliesonthecorrectselectionof ‘guidewords’ and ‘parameters’.Theresultantmatrixisverymuchbasedonpastworldwide experience.ItevolvedfromMethodStudy.InsomerespectsithassimilaritiestoFailure ModesandEffectsAnalysis.Onceagaintheactionsmustberankedinorderofpriority.
HAZID (Chapter5)isastructuredanalysis,whichagainreliesonadetailedunderstandingofthesystemsbeinganalysedandtheprocessarchitecture.Originallyitwas called‘Three-DimensionalHAZOP’inthe1980s.Insomewaysitcanbethoughtofas asystematicallyderived checklist ofscenarios.Oncedefinedeachhastobesubjectto QuantifiedRiskAssessment.
TaskAnalysis (Chapter6)istheanalysisofaroutineorinfrequentoperationandhas someoftheelementsofhazardstudieswithinitsuchassequenceandpriority.Itisprobablybestthoughtofasachecklistmethodasitrelieson‘experience’.
LOPA (Chapter7)isasimplifiedformofRiskAssessment,whichhaspre-defined conditionalprobabilitiesandfailureratedata.Itprovidesfortheexaminationofmajor eventsandgivesclearindicationsoftheneedforadditionalprotectivemeasures.
RelativeRanking (Chapter8)isbasedonpre-preparedtools,whichhavebuiltinto themasetofparametersderivedfromthepastworldexperience.Thisallowsanelement offilteringoftheoptionsbeforetheprojecthasevolvedtoofar.
TheRiskAssessmentScreeningtool(RAST) (Chapter9)hassomelinkstoLOPA (Chapter7)andagainitisbasedonanaccumulationofworldexperienceanddata.
Checklists (Chapter10)areanaidememoireandareagainbasedonhistoricevents. Thesecanbeusedinthedevelopmentofaprocedureortaskanalysis.Theyalsorelatetoa formofHAZID.
Whatif? (Chapter11)hassomeelementsofHAZOP,whichiscausedriven(whatifthere isnoflow?),andHAZID,whichiseffectdriven(whatifthereisamajorreleaseofmaterial Xhere?)
TheonetoolwheretheoutcomeofafailureisassessedinlessdetailisprobablyFailure ModesandEffectsAnalysis (Chapter12),whichusessubjectiveassessmentskills.Insome respectsitissimilartoHAZOPbutisappliedtoapieceofhardware.
FaultTreeAnalysis (Chapter13)usesclearlydefinedlogicofeitherafrequencyorprobability,whichinvolvesadditionandmultiplicationtodefinethecombinationofeventsto definethe‘topevent’ortheeventofconcern.Itcanbe‘topdown’(startwiththefinal event)or‘bottomup’(createthelogic,whichwillcreatethefinalevent).Therulesarewell definedandtheinputdatacanbederivedfromreliabilitystudies.
EventtreeAnalysis (Chapter14)usesonlyprobabilitydatawhicharemultiplied.Itis oftenusedwithFaultTrees.
QuantifiedRiskAssessment (Chapter15)feedsoffvulnerabilityandconsequence models.ItalsousesmethodssuchasFaultTreeandEventTreeanalysis.
Vulnerability (Chapter16)completesthelinktoRiskAssessmentanddefinesthepossibleinjury/damagescenarios
Audits (Chapter17)areastructuredanalysisofthecorporatehealth,beitfinancial and/orsafety,andattempttoidentifythesystematicerosioninstandards.
BowTie (Chapter18)hassomelinksintoHAZOPaswellasFaultandEventTrees.Itisa morevisible(andmoreunderstandable)representationofcausationandmitigationthan FaultTreesandLOPA.The‘threats’useamoredetailedanalysisofthepotentialcauses andexaminessomeofthehumanfactorsinmoredetailthanQuantifiedRiskAssessment. ItalsohaslinkstoAudits.
Thenext(four)methodsarefreestandingandevolvedfromtheneedtoexaminehighriskapplicationssuchaNuclearPower:
Riskassessmentistheonelink,whichiscommontoallmethods.Havingidentifiedthe hazardorpotentialhazarditmustberanked.Somerisk-rankingmethodsarebetterthan others.AsatrivialexampleafullQuantifiedRiskAssessment(QRA; Chapter15)isnotjustifiedforatrivialcaseorroutineoperation.Theassessmentmethodsare:
1. Quantitative wheretheriskisgivenbothmagnitudeandfrequencyusingtoolsuchas Fault TreeandEventTreeanalysisandphenomenology.Theerrorbandsareabouta halforderofmagnitude.
2. Semi-quantitative wheretheriskbothmagnitudeandfrequencyisderivedfrom predetermineddatasets.TypicallythisappliestoLayerofProtectionAnalysis and RankingTools.Theerrorbandscanbeuptoanorderofmagnitude.
3. Qualitative wheretheriskisbasedonexperienceandjudgement.Theerrorbandsare relativelylowastherisksarelowbydefinition.TypicallythismayapplytoTask Analysis.
QuantitativeRiskAssessmentwillinevitablytakeinformationfromhumanandhardware vulnerabilitydata(Chapter16).Thismaybeofaphysicalorapsychologicalnaturefor humans.Likewiseforequipmentthedatawillbeestablishedintabularformat.Thephenomenologyisbasedonexperimentallyverifiedmodelssuchasgas(andwherenecessary liquid)dispersion,thermalradiationandblastfromexplosions.Finallytheassessment musthaveasetofagreedcriteriabywhichtheriskcanbeassessed.
3.1Introduction
ThetopicreferredtohereasHazardStudies,usingtheoriginalICIintent(1),hasseveral othernames.Commononesinclude‘HazardStudies1–6’,ProcessSafetyReviews,Project HazardStudiesandProjectSHEReviews.Confusingly,PHAhasalsobeenusedasan abbreviationforPreliminaryHazardAnalysis.
3.2Definition
HazardStudiesareasystematicanalysisofaproject,bothprocessandcontrol,byselected teamsofexperiencedpersonnel,atdefinedphasesduringitsdevelopment,toensurethat thesafetystandardsbuiltintotheprojectsatisfycorporateandnationalstandardsaswell astheproject,corporateandnationalcriteria.
3.3Description
Themostcommonsetofstudies,carriedoutasappropriateduringtheprojectlifecycle, are:
(1) conceptualdesign
(2) front-endengineering(FEED)design—process
(3) detailedengineeringdesign
(4) constructiondesignverification
(5) precommissioningsafetyreview
(6) post-start-up
ThenumbersarethosereferredtointhetraditionalSafetyStudies,asfirstdevelopedby ICIintheearly1970s [1].‘HazardStudies’hasbeenusedinhistext.Itisdescribedby Swann [2] andadaptedbymanyothercompanies.Thecompositionoftheteamand thedocumentationchangesfromstudytostudyastheprojectdevelopsandthedetail becomesmorefixed.Descriptionsofstudies1–6havebeengivenintheliterature [3] with oneaccountinsomedepthalthoughspecificallyforthepharmaceuticalindustry [4].
Inrecentyears,ithasbeencustomarytoaddtwoextrastudies.These,numberedto leavethetraditionalstudynumbers1–6unchanged,are:
(0)inherentlysafer/lessharmfultotheenvironment (7)decommissioninganddemolition
Itisimportanttorecognisethatthesestudiesformacontinuumand,toadegree,flowinto oneanother.Eachlooksbackattheoutcomesoftheprecedingstudyandwillfeedintothe followingstudy.Thetimingisimportantsothateachanalysisisinplaceforthecorrect phaseoftheprojectbutisnotcarriedouttooearly,whenthedefinitionmaystillbeincomplete,ortoolate,whentheoptionsforchangemaybelimited.Thetimingofstages1–6ina normalprojectlifecycleisshownin Fig.3.1.Obviouslystudy0inherencyprecedesstudy1 anddemolitionorabandonmentfollowsstudy6.
FIG.3.1 Sequenceorhazardstudiesinaproject.
Itisimportanttorealisethatsanctionwillbegrantedinbetweenstudies2and3.This valueisusually 10%.Ifsignificantissuesarenotidentifiedbeforesanction,thereisa graveriskofcostoverrunand/orprojectdelays.
Study0:Inherentsafety
Thisstudyiscarriedoutasthedesignoptionsarebeingidentified;itsaimistoexamine andtoapplywherepossibletheprinciplesofinherentlysafedesign [5].Theteamwillbe smallandthestudywillonlylastabout1day.Memberswillincludeaprojectrepresentativetogetherwithaprocessengineer,chemist,safetyengineerandatechnologyexpert. Ideallytherewouldhavebeenacarefulreviewofthehistoryofthattypeofprocess,includingasearchofaccidentdatabases.
Theinherentlysaferprocessstartswithguidewords,typically:
• Intensify
• Attenuate
• Simplify
• Getitrightfirsttime
• Change
• Substitute
• Eliminate
Intensify:Concentratetheprocessinasmaller,higherpressurereactorandreducethe workinginventoryortotalleakpotential.Anexamplemightbeahigh-pressurecatalytic reactor,whichissignificantlysmallerthantheconventionallowpressurereactor.Another mightbetheuseofalinearreactorinsteadofacontinuouslystirredbackmixedreactor. Anothermightbetheuseof‘green-field’equipment,whichhasbytheverynatureofthe designaverylowinventory;someofthemoderncompactheatexchangerswouldfitinto thisheading.Theendpointisthatwhilethepeakoutflowfromahole(lossofcontainment)maybehigherthetotaloutflowwillbesignificantlylower.
Attenuate:Reducetheworkingpressure/temperaturesuchthattheleakrate—should itoccur—islessorlesslikelytoignite/explode.Anexamplemightbetheuseofrefrigeratedstorageofcryogenicsinsteadof‘green-field’storage.Onceagaintheuseofacatalyst lendstoinherency.
Simplify:Thisisself-evident
Getitrightfirsttime:Avoidtheneedforlast-minutechangeorevenrecognisingthe wholespectrumofconditions,whichmayapplytochoosingthecorrectmaterialsforfabricationandthechoiceofdesignpressureforequipment.Itcanalsomean‘de-clutter’the processandavoidasurfeitof‘add-onsafetyfeatures’,whichdolittleforSHEorefficiency butcreateoperationalproblems.
Change:Whiletheconceptofchangeissimple,itdoesrequireabitofthought!Considerthe‘change’inalayoutsuchastosegregateflammablematerialsfromsourcesof ignitionorthepositioningofavalvesuchthataccessisenhanced—thelayoutoraccess
