Equipment
4.1.Introduction
Thischapterdiscussessafetyissuesrelatedtothedesignandoperationofkeyequipmentusedinthebatchreactionsystems.Someoftheequipmentcoveredincludes:
•••••••••
Vessels, including reactors and storage vesselsCentrifugesDryers
Batch distillation columns and evaporatorsProcess vents and drains
Charging and transferring equipmentDrumming equipmentMilling equipmentFilters
Batchprocesssystemsimposeanadditionaldimensiontothedesignofequipment.Apieceofequipmentinbatchoperationsisfrequentlyusedindif-ferentprocessesduringitslifecycle.Surplusequipmentorexistingequipmentisoftenreusedforadifferentpurpose.Thesepracticesintroducethepossibilityofequipmentbeinginadvertentlyusedoutsideitsintendedoperatingenvelope.Inaddition,usingexistingequipmentfornewprocessmayovertaxexistingancil-laryunitssuchasutilities,disposalfacilities,fireprotectionetc.Inspectionalonemaybeaninadequatepredictoroftheequipmentreliabilityduetochangeofmaterialhandledorchangeinprocesschemistryoverthelifeoftheequipment.Batchoperationsarecharacterizedbyfrequentstart-upandshutdownofequip-ment.Thiscanleadtoacceleratedequipmentaging,andmayleadtounex-pected equipment failure.
Someofthetypesofequipmentusedinbatchreactionsystemsaredis-cussed in more detail below.
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4.EQUIPMENT
Vessels Including Reactors and Storage Vessels (Table 4.1)
Vesselsarekeycomponentsofabatchreactionprocessfacility.Whilereactorsmaybethefirsttypeofvesseltocometomind,vesselsalsoincludestoragetanksforfeedstocks,intermediates,products,wastestreams,etc.Vesselscanvarywidelyindesignwithrespecttofactorssuchassize,pressureandtemperatureratings,andmaterialsofconstruction.However,somecommonconcernsresultfromtheinventoriesofhazardousmaterialspresentinthevessels,thepoten-tiallysevereoperatingconditions(e.g.,hightemperatureandpressure)thatmightposehazards,andthefactthat,inthecaseofreactors,weareintentionallyreleasingthechemicalpotentialenergyoftheprocess,withtheattendantrisksof doing so.
Reactorsaregenerally,butnotalways,ofrobustconstructioninkeepingwiththeelevatedtemperaturesandpressurescommonlyassociatedwiththeprocesschemistry.Significantemphasisisplacedonintegrityofcontainment,withkeyconsiderationsincludingpropertemperatureandpressureratingsfordesign,andproperconsiderationofmaterialsofconstruction.Adequatemixingandheatexchangecapabilitiesareimportantwithrespecttoboththeintendedprocessfunctionofthevessel,andthesafeoperationofthevessel;inadequatecoolingand/ormixingarecommoncausalfactorsforrunawayreactionsthatcanleadtovesselrupture.Reactorsalsooftensharethesafetysignificantperfor-manceissuesdescribedbelowforstoragevessels.Aspreviouslydiscussed,theflexibilityofprocessing,typicalinbatchfacilities,cancomplicatetheprovisionofdesignfeaturesthataddressalloftheseaboveconcernsforallpotentialusesof the reactor.
Storagetanksaregenerallydesignedbaseduponthevaporpressureoftheircontents,andcanrangefromlowpressure(API-type)tankstohighpressuretanks for compressed gases or pressurized liquids.
Nonrefrigerated,pressure-liquefiedgasessuchasliquefiedpetroleumgases(LPGs)willflashuponreleaseandcoolequipmenttotheextentthattheequip-mentmayfailduetocoldembrittlement.Boilingliquidexpandingvaporexplo-sions(BLEVEs)canresultwhenvesselscontainingthesematerialsareexposedtoexternalfires.Releasesofflammableliquefiedgasescanalsogiverisetofires,vapor cloud explosions, and fireballs (e.g., during BLEVEs).
Refrigeratedliquefiedgasesarestoredatmuchlowerpressuresand,accordingly,generallyposemuchlessofahazard.However,BLEVEhazardsstillexistforfireexposuresituations.Bothpressurizedandrefrigeratedlique-fiedgasesposeconcernsofexposuretopersonneltoextremelycoldliquidsandvaporsuponrelease,alongwithanytoxicityorasphyxiationhazardsinherenttotheparticularliquid.Pressurizedandrefrigeratedstorageiscoveredindetailbyindustrystandards,codesandguidelines,specificallybytheNFPAforsmallerquantities and API for larger quantities.
Atmosphericstoragetanksarenormallyusedforliquidmaterialsthatarebelowtheirboilingpointatambientconditions.Hazardsassociatedwith
4.1.Introduction
37
atmospherictanks(ambientpressureto15psig)includeoverpressureandunderpressure,vaporgeneration,spills,tankrupture,fire,andproductcontam-ination.Inaddition,settlingoffoundations,andseismicandwindloadingsareimportantconcerns.(SeeAPIRP620andRP650.)Althoughatmosphericstor-agetanksarenotsubjecttoBLEVEs,releasesofflammableorcombustibleliq-uidscanleadtopoolfires.Sincethepotentialconsequencesoffiresincreaseasinventoriesincrease,itisadvisabletoapplyprinciplesofinherentsafetythroughreductionofinventoriesandelimination,wherepossible,ofknownignitionsources.
Thecontaminationofmaterialintanksbytheintroductionofincompatiblematerialsormaterialofthewrongtemperaturecancauserunawayreactions,polymerization,hightemperatureexcursions,orunderpressurizationofthetank.Toavoidpotentialcontaminationofproductsorroutingwrongmaterialstotanks,safeguardsshouldbeimplemented,suchasclearlylabelingpiping,valvesandmanifoldstothetank;useofclearandwell-definedoperatingproce-dures; and provision of periodic operator training.
Forvesselscontainingflammableliquids,wherethevesseldesignpressureisinsufficienttocontainadeflagrationoropenloadingisperformed,consider-ationshouldbegiventoprovidinganinertgasblanket(e.g.,nitrogen)toreducethe oxygen concentration and prevent fires or explosions.
Storagevesselsalsoincludebinsandsilosusedforthestorageofsolidmate-rialssuchaspellets,granules,ordusts.Theprimaryhazardinthestorageofsuchmaterialscomesfromthedustthatisgeneratedduringthemechanicalhandlingofthesematerials.Suspensionsofcombustibledustsinthevesselvaporspaceabovethematerialcanbeignitedleadingtofiresandexplosions.Sincedustpro-ductiontypicallycannotbeprevented,othermeansofexplosionpreventionmustbeapplied.Ignitionsourcesshouldbeminimized,andexplosionventingofvessels(includingbinventfiltersorbaghouses)shouldbeconsidered.Careshouldbetakenduringthedesignofabintoreducehorizontalsurfacesinsidethebinwherematerialcanremainandcreateahazardwhenthebinisopenedformaintenance;theairabovesuchareashasbeenknowntoexplodewhileworkinsidethebinswasbeingperformedduringnormalrepairs.Additionally,thevesselscanbeinertedinamannersimilartothatusedforatmosphericstor-agetanks(NFPA68and69).Thepneumatictransferofsolidscanalsobeper-formedusinganinertorareducedoxygenconcentrationgaswithaclosedloopreturn to the sending tank.
Amongtheprincipalreasonsforprovidinginertingonreactorsandvesselsisthedesirabilityofeliminatingflammablevapor–airmixturesthatcanbecaused by:
•Addition of solids through the manhole.
•Materialshavinglowminimumsparkignitionenergies,orautoignitiontemperatures
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4.EQUIPMENT
•Potential ignition sources that cannot be controlled adequately, such as:–spontaneous combustion
–reactivechemicals:pyrophoricmaterials,acetylides,peroxides,andwater-reactive materials
–staticelectricity:materialtransferwherelinesandvesselsarenotgroundedproperly,agitationofliquidsofhighdielectricstrength(lowconductivity),additionofliquidsofhighdielectricstrengthtovessels,additiontooragitationofliquidsinvesselshavingnonconductivelinersAnotherpurposeofinertingistocontroloxygenconcentrationswhereprocessmaterialsaresubjecttoperoxideformationoroxidationtoformunsta-blecompounds(acetylides,etc.)orwherematerialsintheprocessaredegradedbyatmosphericoxygen.Aninertgassupplyofsufficientcapacitymustbeensured. The supply pressure must be monitored continuously.
Thedesignershouldconsidertheneedforadditionalmeasurestosupplyinertgas.Particularattentionmustbegiventothefollowingsituation:Inthecaseoflocallyhighnitrogenconsumption(i.e.,whenalargekettleisinerted),thepressureinthemainlinemaydropsofarthatthemainscouldbecontami-natedbygasesorvaporsfromotherapparatusconnectedatthesametime.Dependingupontheapplication,thequalityofinertgas(e.g.,watercontent,contaminants) can be important to process safety.
Therequiredlevelofinertingmustbeensuredbytechnicalandadministra-tive measures, for example:
•control and monitoring of inert gas flow and inert gas pressure•continuous or intermittent measurement of oxygen concentration
•explicitinformationinthestandardoperatingproceduresorinthepro-cesscomputerprogramforthecorrectproceduretoachieveasufficientlevel of inerting
Arigorousmechanicalintegrityprogramtoensuretheproperdesign,con-struction,andmaintenanceofreactorsandstoragevesselsisessentialinordertopreventleaksormoreseriousvesselfailuresarisingfromcorrosionorothermechanicalfailure.Theleakingofflammableandtoxicliquidscanhaveserioussafetyandenvironmentalconsequences,whicharecompoundedbythelargeinventories that can be held in these vessels.
Centrifuges (Table 4.2)
Sincecentrifugesaresubjecttothehazardsinherentinallrotatingequipment,thedesignershouldfirstconsiderwhetherother,safermethodsofseparation(suchasdecantersorstaticfilters)canbeused.Ifitisdeterminedthata
4.1.Introduction
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centrifugemustbeused,thedesignshouldbereviewedtoensurethatitisassafeand reliable as possible.
Agooddiscussionofcentrifugesafetydesignfeaturesandoperatingprac-tices is found in an IChemE publication (1987).
Potentialproblemsassociatedwithcentrifugesincludemechanicalfrictionfrom bearings; vibration; leaking seals; static electricity; and overspeed.
Vibrationisbothacauseofproblemsandaneffectofequipmentproblems.Thepotentialdestructiveforceofanout-of-balanceloadhasledtosettinglowershutdownlimitsonthemagnitudeofvibrationthanotherrotatingequipment.Flexibleconnectionsforprocessandutilitylinesbecomeamustsothesevibra-tionproblemsarenottransmittedtoconnectedequipment.Flexiblehoseswithlinershavingconcentricconvolutions(bellowstype)avoidthesharppointsinherentwithspiralmetallicliners.Byavoidingthesharppointthelinerislesslikely to cut the exterior covering.
Groundingofallequipmentcomponents,includinginternalrotatingparts,mustbeensuredinitiallyandperiodicallythereafter.Groundingviasometypeofbrushorotherdirectcontactispreferredtogroundingviathebearingsystemthroughthelubricatingmedium(unlessconductivegreasesareused).Useofnonconductivesolventscomplicatestheeliminationofstaticelectricitycon-cerns;useofconductivesolventsorantistaticadditivesshouldbeconsideredwhere feasible.
Forflammableand/ortoxicmaterialsalloftheprecautionsforapressurizedsystemshouldbeconsidered.Forexample,whenacentrifugeispressurized,overpressureprotectionisrequired,evenifthepressurizationisaninertgas.Relievingofthepressuretoaclosedsystemorsafelocationmustbeconsidered.
Dryers (Table 4.3)
Thechoicebetweendifferenttypesofdryersisoftenguidedbythechemicalsinvolvedandtheirphysicalproperties,particularlyheatsensitivity.Aswhenselectingotherequipment,thedesignershouldfirstaskifthestepisnecessary;ifso,whetherthisisthecorrectorsafestprocessstep.Doesthematerialbeingpro-cessedhavetohavealloftheliquidremoved?Canthedownstreamsteporcus-tomer use the material in a liquid, slurry or paste form?
Someofthehazardsindryingoperationsare:vaporizationofflammableliquids;presenceofcombustibledusts;overheatingleadingtodecomposition;andinertingleadingtoanasphyxiationhazard.Forheatsensitivematerial,lim-itingthetemperatureoftheheatingmediumandresidencetimeofthematerialareusedtopreventdecomposition.Inventoriesofhazardousmaterialsshouldbeminimized.Preventivemeasuresincludeadequateventilationandexplosionventing,explosioncontainment,explosionsuppression,inerting,eliminationofignitionsources,andvaporrecovery.Instrumentationmayincludeoxygen
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4.EQUIPMENT
analyzersandsensorsfortemperature,humidity,etc.Effluentgasesshouldbemonitoredforflammabilitylimits.TheIChemEbook(1990)shouldbecon-sulted for a thorough review of fires and explosions in dryers.
Severalgeneralprinciplesmaybeappliedtoequipmenthandlingcombusti-ble dusts:
•design equipment to withstand a dust explosion;•minimize volume filled by dust suspension;
•minimize(monitor)mechanicalfailureandoverheating(bearing,rollers,mills);
•eliminate static electricity and other sources of ignition;•minimize passage of burning dust by isolating equipment;
•provideexplosionprevention(e.g.,byinerting)andprotection(e.g.,sup-pression, venting, or isolation);•provide fire protection;
•maintain design operating conditions via management of change.
Batch Distillation Columns and Evaporators (Table 4.4)
Batchdistillationequipmentcanrangefromafree-standingcolumnwithareboiler,condenser,receiver,andvacuumsystem,totheuseofajacketedreac-torwithacondenser.Distillationofteninvolvesthegenerationofcombustiblevaporsintheprocessequipment.Thisnecessitatesthecontainmentofthevaporwithintheequipment,andtheexclusionofairfromtheequipment,topreventthe formation of combustible mixtures that could lead to fire or explosion.
Sincedistillationistemperature,pressure,andcompositiondependent,specialcaremustbetakentofullyunderstandthepotentialthermaldecomposi-tionhazardsofthechemicalsinvolved.Otherpotentialhazardscanresultfromthefreezingorpluggingincondensers,orblockedvaporoutlets,whichmayleadtovesseloverpressurizationiftheheatinputtothesystemisnotstopped.Emphasisshouldbeplacedupontheuseofinherentlysaferdesignalternativesusingconceptssuchas:limitingthemaximumheatingmediumtemperaturetosafelevels;selectingsolventswhichdonotrequireremovalpriortothenextprocessstep;usingtemperedheattransfermediumtopreventfreezinginthecondenser;andlocatingthevesseltemperatureprobeonthebottomheadtoensure accurate measurement of temperatures, even a low liquid levels.
Process Vents and Drains (Table 4.5)
Processventsanddrains,includingemissioncontroldevices,areoftenover-lookedbutareimportantelementsinthesafetyofbatchsystems.Inadequateattentiontotheseitemscanresultinincompatiblechemicalmixtureswithinthe
4.1.Introduction
41
system;formationofcombustibleatmospheres,oroverloadingofemissioncon-trol equipment. Some items requiring special attention are:
•elimination of pockets or traps in pipelines;
•identificationandconsiderationofallprocessfluidsorequipmentthatcouldsimultaneouslydrainorventintocommonpipelinesorequipment;•thepotentialneedtoprescrubthestreambeingventedpriortomixingwith other streams;
•proper selection of materials of construction.
Inadditiontotheinformationpresentedinthischapter,refertoChapter3,EquipmentConfigurationandLayout,forfurtherdiscussionsonsharedventand drain systems.
Charging and Transferring Equipment (Table 4.6)
Duetothenatureofbatchoperations,transferringandchargingofprocessmaterialsisacommonactivity.Thiscanentailgas,liquids,and/orsolidshan-dlingviaopenequipment.Thismayincludepumpingofliquidsfromdrumsordumpingofsolidsfromothercontainersintoanopenvessel,shovelingmaterialinto a dryer, or making temporary connections such as at hose stations.
Primaryconcernsincludetheoflossofcontainmentandthepotentialforexposureofoperatingpersonneltohazardousmaterials;thepotentialforotherhazardssuchasfiresorexplosions;andtheergonomicissuesinherentinmanip-ulatinglarge,heavycontainers.Thefirsttwoconcernsareofparticularsignifi-canceinbatchoperations,sinceoperatingpersonnelareoftenmorefrequentlyandmoreintimatelyexposedtothebatchprocessesthanistypicallythecasewith continuous processes.
Some commonly applied controls include
••••••
providing enclosed charging systems, where feasible;use of localized ventilation;
proper selection and use of personal protective equipment;
use of mechanical assists for handling drums and other containers;procedures and training; and
interlockingvesselopeningstopreventopeningwhilethevesselispressurized.
Drumming Equipment (Table 4.7)
Manyofthematerialhazardspresentinbatchprocessingarealsopresentduringthedrummingofmaterialsoutoftheprocess.However,thereareadditionalconsiderationsuniquetothisoperation,includingthemechanicalhandlingofmassiveobjects,potentialforpunctureofcontainers,andlossoflinerintegrity.Someofthehazardspresentinthedrummingstagehavethepotentialforoverpressurizationleadingtoreleaseofchemicalsandoperatorexposure,
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4.EQUIPMENT
underpressurizationofdrums,oruncontrolledreactionsoccurringafterdrum-ming,leadingtopotentialfiresorexplosions.Specialconsiderationneedstobegiventodrummedmaterialsthatareshock/heatsensitiveaswellasdrummedmaterials that degrade over time.
Milling Equipment (Table 4.8)
Millingequipmentmaybeusedinbatchsystemswhereitisnecessarytoreduceparticlesizeorproductagglomeration.Aprimaryhazardassociatedwithmillingequipmentisthetemperatureincreasethatcanbeimpartedtothematerialduringthemillingoperation,particularlywhenproductflowthroughthemillissignificantlyreducedorinterrupted(similarconcernsexistforothersolidshan-dlingoperationssuchasblendingand,toalesserdegree,particlesizesepara-tionssuchasscreeningorsieving).Thiscanleadtoignitionordecompositionofcombustibleorunstablematerialsthatcouldleadtofiresorexplosionsinthemillingequipment.Additionally,firesorexplosionscanresultfromthepres-enceofcombustibleduststypicallypresentinthemillingequipment,shouldotherignitionsourcesbepresent.Otherconcernsincludethepotentialforexposure of operating personnel to chemical hazards.
Anumberofdesignalternativesshouldbeconsideredwhenmillingmateri-als that are combustible or are temperature sensitive, such as
•monitoring of milling temperature;
•shaft speed sensors to detect pluggage in the mill; and
•instrumentationorinspectionstoensureproductflow,thuslimitingmaterial temperature rise to a safe level.
Otherignitionsourcesshouldbeidentifiedandexcludedthroughconsider-ation of
••••
static electricity concerns, including proper bonding and grounding;proper area electrical classification;
proper selection, location, and maintenance of bearings; and
removal of tramp materials from the feed to the milling equipment.
Milling of impact-sensitive materials should generally be avoided.
Filters (Table 4.9)
Oneoftheprimaryconcernsforfiltersisthelossofcontainmentofflammableandtoxicmaterialsandoperatorsafetyduringthefrequentopeningandclosingoftheequipment(e.g.,forchangingfilterelementsorunloadingfilters).Inher-entlysaferprocessalternativesshouldbeconsideredtoeliminateorlessentheneedforfiltration.Self-cleaning,automaticbackwashing,orsluicingfiltersshouldbeconsideredforpyrophoricortoxicmaterialsastheydonothavetobe
4.2.Case Studies
43
openedordisassembledtoremovethefiltercake.Filtersforliquidserviceshouldbeprovidedwithfire-reliefvalvesandsafeoperatingproceduresforout-of-service conditions.
Baghousefiltersarenormallylow-pressureunits.Theycanvaryinoperat-ingconditionsfromhotandchemicallyaggressivetocoolandinert.Hotfeedmayleadtoexceedingthetemperatureratingofthefiltersandcouldevenresultinabaghousefire.Aswithallfilters,notexceedingthedesigndifferentialpres-sureisimportanttoboththeprocessstabilityandsafety.Asthesolidisremovedfromthegasstreamandissubsequentlyhandledforrecoveryordisposal,alloftheconventionsandconcernsforhandlingdust,powdersandothersolidsapply.Thesystemshouldbeprotectedfromthepotentialofdustdeflagrationbytheuseofpressurerelieforsuppressiondevices.Adiscussionofsafetyconsider-ationsforthesetypesofsystemsisfoundinDustExplosionPreventionandPro-tection Part 1–3.(IChemE 1992).
Insummary,itmustberememberedthatbothdesignandoperationsareimportant in maintaining the integrity of the process and equipment.
4.2.Case Studies
Batch Pharmaceutical Reactor Accident
Whiletwooperatorswerechargingpenicillinpowderfromfiberdrumsintoareactorcontainingamixtureofacetoneandmethanol,anexplosionoccurredatthereactormanhole.Thetwooperatorswereblownbackbytheforceoftheexplosion, and were covered with solvent-wet powder.
Theincidentwasinitiatedbytheignitionofsolventvapors,whichresultedinadustexplosionofthedrypowder.Thesolventmixtureinthereactordidnotignite.Testsonthepolyethylenelinersinsidethefiberdrumsshowedthattheywerenonconducting;whileanattempthadbeenmadetogroundtheliners,thiswouldnothavebeeneffectiveforthenonconductivepolyethylene.Themostprobablecauseoftheignitionwasanelectrostaticdischargefromthepolyethyl-enelinerduringreactorcharging.whichhadbeengroundedatthetimeoftheincident
Afterthisaccident,thecompanyinstitutedthefollowingprocedures(Drogaris 1993):
•Requiringnitrogeninertingwhenpouringdrysolidsintoflammablesolvents
•Addingdrypowdertothereactorbymeansofgroundedmetalscoops,wherepossible,ratherthanbypouringindirectlyfromdrumswithpoly-ethylene liners
•Using only conductive polyethylene liners
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4.EQUIPMENT
•Usingaclosedchargingsystemratherthanpouringdrypowdersintoflammable solvents directly via an open manhole
•Performinganelectrostatichazardreviewofthewholeplantandalltheprocesses whenever powders and flammable solvents are used
Ed.Note:Eventhoughthisincidentinvolvedareactor,itappliesaswelltoanyvessel,open-manhole,chargingoperation.Mostlikelythelinerswerelooseandtheoperatorsnotgrounded.Iffixedlinerswereinplaceandtheoperatorsgrounded,theaccidentmightnothaveoccurred.Anotherproblemthatcanbeavoidedbyusingclosedchargingsystemsisthevolumetricdisplacementoffluidsfrom the vessel during addition of solids.
Seveso Runaway Reaction
OnJuly10,1976anincidentoccurredatachemicalplantinSeveso,Italy,whichhadfar-reachingeffectsontheprocesssafetyregulationsofmanycoun-tries,especiallyinEurope.Anatmosphericreactorcontaininganuncompletedbatchof2,4,5-trichlorophenol(TCP)wasleftfortheweekend.Itstemperaturewas158°C,wellbelowthetemperatureatwhicharunawayreactioncouldstart(believedatthetimetobe230°C,butpossiblyaslowasl85°C).Thereactionwascarriedoutundervacuum,andthereactorwasheatedbysteaminanexternaljacket,suppliedbyexhauststeamfromaturbineat190°Candapressureof12bargauge.Theturbinewasonreducedload,asvariousotherplantswerealsoshuttingdownfortheweekend(asrequiredbyItalianlaw),andthetemperatureofthesteamrosetoabout300°C.Therewasatemperaturegradientthroughthewallsofthereactor(300°Contheoutsideand160°Contheinside)belowtheliquidlevelbecausethetemperatureoftheliquidinthereactorcouldnotexceeditsboilingpoint.Abovetheliquidlevel,thewallswereatatemperatureof300°C throughout.
Whenthesteamwasshutoffand,15minuteslater,theagitatorwasswitchedoff,heattransferredfromthehotwallabovetheliquidleveltothetoppartoftheliquid,whichbecamehotenoughforarunawayreactiontostart.ThisresultedinareleaseofTCDD(dioxin),whichkilledanumberofnearbyanimals,causeddermatitis(chloracne)inabout250people,damagedvegetationnear the site, and required the evacuation of about 600 people (Kletz 1994).
Pharmaceutical Powder Dryer Fire and Explosion
Anoperatorhadtesteddryersamplesonanumberofoccasions.Afterthelastsampling,heclosedthemanholecover,putthedryerundervacuum,andstartedrotationofthedryer.Afewminuteslateranexplosionandflashfireoccurred,whichself-extinguished.Noonewasinjured.Investigationsrevealedthatafter
4.4.Process Safety Practices
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thelastsampling,thedryermanholecoverhadnotbeensecurelyfastened.Thisallowedthevacuumwithinthedryertodrawairintotherotatingdryerandcreateaflammablemixture.Theignitionsourcewasprobablyanelectrostaticdischarge(theTeflon®coatingontheinternalliningofthedryercouldhavebuilt up a charge). No nitrogen inerting had been used (Drogaris 1993).
Afterthisincident,thefollowingprecautionswereinstitutedtopreventsimilar incidents from occurring in the future:
•Nitrogenpurgingiscarriedoutbeforechargingorsamplingofthedryer•Iftheabsolutepressurerisestoabout4psia,therotationstops,analarmsounds, and a nitrogen purge starts automatically
4.3.Key Issues
SafetyissuesinbatchreactionsystemsrelatingtoequipmentarepresentedinTables 4.0 through Table 4.9. The various tables are organized as follows:
Table 4.0Table 4.1Table 4.2Table 4.3Table 4.4Table 4.5Table 4.6Table 4.7Table 4.8Table 4.9
General
Reactors and VesselsCentrifugesDryers
Batch Distillation columns and evaporatorsProcess Vents and Drains
Charging and Transferring EquipmentDrumming EquipmentMilling EquipmentFilters
Tables4.0,4.1,and4.6containinformationthatmaybeapplicabletothewholerange of equipment and operations.
These tables are meant to be illustrative but not comprehensive.
4.4.Process Safety Practices
Listedbelowarepracticesthatshouldbeconsideredinthedesignandsafeoper-ation of equipment in batch reaction systems.
•Whenusinginertgas,provideprotectionagainstpersonnelasphyxiationhazards
•Protectagainsttheaccumulationofelectrostaticchargeswhichcancauseignition.Thismayincludethebondingandgroundingofthetank,piping,
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•
•••
••
••••••••••••
andotherancillaryequipmentandtheuseofbottomordiptubeadditionof liquids to minimize material splashing in the tank.
Provideadequatefixedfireprotectionfortanksandvesselscontainingflammable,unstableorreactivematerials.Thiscanincludefireloopswithhydrantsandmonitorsinthestoragearea,foamsystemsforindivid-ualtanks,anddelugespraysystemstokeeptheexposedsurfacesoftankscool in case of fire in an adjacent tank.
Installflamearrestersonatmosphericventstopreventfireontheoutsideof the tank from propagating back into the vapor space inside the tank.Providefireresistantinsulationforcriticalvessels,piping,outletvalveson tanks, valve actuators, instruments lines, and key electrical facilities.Provideremotecontrolled,automatic,andfire-actuatedvalvestostoplossoftankcontentsduringanemergency;providefireprotectiontothesevalves.Valvesshouldbeclose-coupledtothetank,andmustberesistant to corrosion or other deleterious effects of spilled fluids.Vessels should be provided with overpressure relief protection.
Providethecapabilitytoaddaconsiderableamountofcoolantordiluentto reduce the reaction rate if required. This measure requires:
–choiceofanappropriatefluidwhichdoesnotreactwiththereactionmixture
–sufficient free volume in the reactor
–piping, instrumentation, etc. to add the fluid in the time requiredProvidethecapabilitytorapidlydepressurizethereactortoasafeloca-tion, if needed.
Addaninhibitortostopthereaction.Thismeasurerequiresintimateknowledgeofhowthereactionratecanbeinfluencedandwhethereffec-tive mixing/inhibition is possible.
Dumpthereactorcontentsintoavesselwhichcontainscolddiluent.Thisoptionalsorequiresparticularcarethatthedumpinglineisnotblockedor does not become blocked during the dumping procedure.
Forreactorscontainingflammableliquids,wherethereactordesignpres-sureisinsufficienttocontainadeflagration,considerationshouldbegiven to providing an inert gas blanket (usually nitrogen).
Matchbatchsizetocontainersizeofcriticalcomponents,usinganinte-gral number of whole containers, where possibleDouble check materials being added to reactorComplete batch loading sheets for each batch runUse of operator sign-off sheets
Preweigh reactants before transferring to reactor
Verify raw materials (certificate of analysis for critical materials)Use of a staging area
Useofdedicatedandproperstorageandunloadingareasthatdon’texpose other operating and production facilities
4.4.Process Safety Practices
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•Maintain safe handling and storage practices
•Providefiresuppressiondelugeprotectioninareashavinghighconcen-trations of flammables or combustibles
•Test reactive and critical raw materials prior to use•Sample to confirm concentrations•Label all containers
•Use unique containers (e.g., colors, shapes) where appropriate
•Identifyallprocessandutilitylines(writtenmaterialnameandcolorcoded)•Indicate direction of flow, where applicable
•Useuniquefittings/connections/couplings(e.g.,colorsorsizes)whereneeded•Match batch size to equipment capabilities•Use appropriate materials of construction
•ConsiderInherentlySaferDesignalternatives(e.g.,towithstandmaxi-mum upset conditions—temperature, pressure, flow)•Use hard piping where possible
•Minimize pipe lengths where possible
•Useheatingmediathatwillnotexceedthesafetemperaturelimitsfortheprocess
•Design for ease of cleaning
•Remove abandoned lines and equipment
•Installvalvesandlocalinstrumentationwheretheywillbeaccessibleandvisible
•Where used, include check valves in mechanical integrity program•Provide adequately designed relief devices
•Provide separate vent systems for incompatible materials
484.EQUIPMENTTable 4.0: GeneralNo.Concern/IssueOverpressure1.Blockage of•Size piping system to maintain minimumpiping, valves orrequired velocity to avoid depositionflame arresters due•If appropriate, eliminate flame arrester or useto solid deposi-parallel switchable flame arresters with flowtion. Potential formonitoringsystem•Monitor flow in lineoverpressure.•Remove solids from process stream (use knock-out pot, filter, etc.)•Install insulation/tracing of piping to minimizesolid deposition (freezing/precipitation)•Recirculate material in lines prone to soliddeposition•Use flush mounted valves where required•Periodically clean via flushing, blowdown, inter-nal line cleaning devices (e.g., “pigs”)•Design piping for maximum expected pressure•Install adequately designed emergency reliefdevice (ERD)Underpressure2.Failure of vacuumsystem controlresulting in possi-bility of vesselcollapse.•Design vessel to accommodate maximumvacuum (full vacuum rating)•Provide vacuum relief device/system (can be asource of oxygen in vapor space resulting inflammable atmosphere)•Provide a vacuum alarm•Interlock to inject inert gas•Select vacuum source to limit vacuum capability3.Uncontrolled con-densation/absorp-tion of vaporphase componentresulting invacuum creationinside vessel.•Design vessel to accommodate maximumvacuum (full vacuum rating)•Use blanketing gas pressure control system tominimize vacuum•Provide vacuum relief device/system•Blanket the condenser•Insulate equipment to mitigate effect of ambienttemperature changes, e.g., thunderstorm•Interlock cold liquid feeds with heat source (e.g.,distillation column)ASMG VIIIFMEC 7-59NFPA 99CAPI 2000CCPS G-11DIERSFMEC 7-59NFPA 69API 2028CCPS G-11ASME VIIILiptak 1982Wilday 1991Potential Solutionsand Control MechanismsAdditionalResourcesTable 4.0: General49Potential Solutionsand Control MechanismsAdditionalResourcesNo.Concern/IssueFire/Explosion4.Deflagration of•Design vessel to accommodate maximumvapor caused byexpected deflagration pressureair leakage into•Provide deflagration pressure reliefequipment operat-device/systeming under vacuum.•Provide oxygen analyzer with activation of inertPossibility ofgas addition on detection of high oxygenfire/explosion.concentration•Provide continuous inert purge to check forleaks before start-up•OperatebelowtheLowerFlammableLimit(LFL)NFPA 68NFPA 695.Ignition of•Design system to prevent condensation incondensedductwork or buildup of deposits by providingflammable vaporsmooth surfaces, elimination of potential pointsor solid deposits inof solids/liquid accumulation.ductwork/ piping.•Periodicallyflushand/orsteamcleanpiping/ductsPossibility of•Include cleaning procedure in process write-upfire/explosion.•Provide written cleaning procedure andresponsibility•Provide provision for drainage of ducts (e.g.,sloped, low point drains)•Eliminate ignition sources within the ductwork•Bond and ground all pipe and duct work•Eliminate flammables or combustibles•Provide inert atmosphere•Install dilution system to keep flammable con-centration below lower flammable limit (LFL)•Install on-line flammable gas detection and acti-vation of inerting system•Install automatic sprinkler system•Install deflagration vents•Provide automatic isolation of associated equip-ment via quick closing valves•Provide design system to contain overpressurewhere practical•Provide weak sections in piping and duct work•Operate above dew point or sublimation point•Avoid use of static generating materials (plasticor rubber) for piping and ductwork systems inhazardous serviceCCPS G-41FMEC 7-59NFPA 69NFPA 77NFPA 6850Potential Solutionsand Control Mechanisms4.EQUIPMENTNo.Concern/IssueFire/Explosion6.Inadequate venti-lation in ducts dueto partial obstruc-tions or closeddampers leadingto creation offlammable atmo-sphere. Possibilityof fire/explosion.AdditionalResources•Design dampers so that system will handle theminimum safe ventilation rate at maximumdamper throttling•Provide damper mechanical position stop to pre-vent complete closure of damper•Eliminate ignition sources within the ductwork•Use bonding and grounding•Eliminate flammables or combustible by materialsubstitution•Use inert atmosphere•Design ventilation system to keep flammableconcentration below lower flammable limit•Provide on-line flammable gas detection andactivation of inerting system•Install automatic sprinkler system•Install deflagration vents•Provide automatic isolation of associated equip-ment via quick closing valves•Provide weak sections (for pressure relief) inpiping and duct work•Design system to accommodate maximumexpected deflagration pressure•Provide prescrubbers/condensers to reduce loadin duct•Design where natural circulation is sufficient toprevent accumulation of flammables•Eliminate flammable solvent (e.g., substitutewater-based solvent)•Design system for deflagration pressure contain-ment where practicalCCPS G-41NFPA 13NFPA 15NFPA 16NFPA 68NFPA 697.Inadequate circu-lation in equip-ment causingaccumulation offlammable pock-ets. Possibility offire/explosion.CCPS G-41NFPA 698.Prematureshut-•Design where natural circulation is sufficient toNFPA 69downoffans/venti-prevent accumulation of flammables and/or cre-lationsystemation of hot spotsimmediatelyfol-•Design to contain overpressure where practicallowingshutdownofheatinput(prior•Provide postventilation interlocks and/or operat-ing procedures to keep fans running for a suffi-tosufficientcool-cient time after shutdown of heating systeming)resultinginhotspotsandflamma-blepockets(dryers,carbonbeds,andthermaloxidizers).Possibilityofsubse-quentignitionresultinginfireorexplosion.Table 4.0: General51Potential Solutionsand Control MechanismsAdditionalResourcesNo.Concern/IssueFire/Explosion9.Production of finepowder duringauxiliary process-ing. Possibility of adust ordust/hybridexplosion.•Operate below minimum oxygen concentration•Maintain good housekeeping•Grind/blend under inert atmosphere•Provide damage limiting construction•Provide design to contain overpressure wherepractical•Maintain inlet temperature of heating mediumsufficiently below the minimum ignitiontemperature•Use dedicated exhaust ducts•Vent individual pieces of equipment throughconservation vents to prevent back flow•Install flame arresters at vessel vents, whereapplicable•Design to contain overpressure where practical•Maintain ignition source control•Maintain use of inert atmosphere•Provide automatic isolation via quick closingvalves of manifold duct system on detection offire/flammable atmosphere or overpressure induct system•Provide automatic sprinkler system/inerting gas•Provide deflagration vents•Provide deflagration suppression system•Monitor flammable atmosphere/fire•Provide nitrogen blocks (nitrogen injection tostop flame propagation) or other explosion isola-tion measuresNFPA 68NFPA 69NFPA 650NFPA 65410.Manifolding ofventilation exhaustducts of severalpieces of equip-ment from severalprocesses. Possibil-ity of spread offire or deflagrationfrom one locationto the next.NFPA 13NFPA 15NFPA 16NFPA 68NFPA 6911.Pyrophoric mate-rial exposed to airwhen equipment isopened for clean-ing/maintenance.Possibility of fireand operatorexposure.•MaintaingoodoperatingandcleaningproceduresCCPS G-32•Provide fixed water spray, if appropriateCCPS G-41•Use inherently safe material, where possibleNFPA 15•Provide inert purge•Deactivate pyrophoric material prior to exposingto air•Purchase/design equipment that does not requireopening•Ensure operating procedures are in place topurge with inert gas prior to opening52Potential Solutionsand Control Mechanisms4.EQUIPMENTNo.Concern/IssueOperator Exposure12Emission of toxic,flammable or cor-rosive vaporswhen equipment isopened for clean-ing/maintenanceor during chargingof hazardousmaterial. Possibil-ity for operatorexposure.AdditionalResources•Provide local exhaust ventilation connected to aCCPS G-41disposal system (vent condenser, adsorber, scrub-ber or incinerator)•Operator shuts down operation in response tovapor detection alarm•Develop and implement appropriate operatingprocedures•Provide operation to remove operator from zoneof danger•Purge vessel prior to opening•Use inherently safer materials, where possibleManagement of Change13.Equipment used indifferent processesduring its lifecycle.Surplus equipmentor existing equip-ment reused fordifferent use. Pos-sibility of equip-ment being usedoutside its safeoperatingenvelope.•Procure equipment that can be used in otherprocesses (current or future) without operatingclose to its design envelope•Design equipment for the entire system toaccommodate the maximum expected pressure•Select a material of construction that has a wideapplication range•Verify suitability of equipment for new service(material of construction, pressure and tempera-ture rating, etc.)•Verify suitability of relief device for new service•Develop and implement appropriate cleaningand decontamination procedures14.•Ensure that the equipment is able to handle theUsing existingequipment fornew process chemistry, and that the demands ofnew process maythe new process on ancillary units are also metovertax existing•Perform process hazards analysisancillary units e.g.,•Perform management of change reviewutilities/disposal/fire protection etc.Possibility of haz-ardous event.Use of temporaryequipment forprocessing•Implement management of change procedureCCPS G-1CCPS Y-2815.Table 4.0: General53Potential Solutionsand Control MechanismsAdditionalResourcesNo.Concern/IssueManagement of Change16.Equipment inspec-•Reevaluate and possibly reset inspection intervalstion may provide awhen equipment is used for handling differentpoor prediction ofchemistryequipment safety•Perform management of change reviewdue to change ofmaterial handledor change in pro-cess chemistryover the life ofequipment.Not “in-kind”•Ensure that the replacement satisfies the require-replacements (e.g.,ments of dutygaskets, rupture•Implement management of change reviewdisks, packing,processmechanical seals)resulting in failure.Possibility of haz-ardous release.Loss of Containment18.Cyclic nature of•Implement mechanical integrity programbatch process (e.g.,•Design equipment for easy replacementstart/stop, thermalcycling). Possibil-•Consider demand of cycling while designingequipment and controlsity of mechanicalwear and tear.Possible loss ofcontainment.•Procure equipment that can be used in otherAvailable equip-ment determinesprocesses (current or future) without operatingthe process chem-close to its operating envelope.istry selected.•Provide equipment with comparable pressureOperating close torating for the entire systemthe safe operating•Match batch sizes to equipment capabilitiesenvelope of theequipment and therelief capability.Frequent start/stop•Minimize frequent start/stop by proper sizing ofof equipment mayequipment (e.g. pump capacity)lead to equipment•Implement mechanical integrity programfailure.•Develop procedure to investigate causes for fre-quent reset of control•Minimize frequent start/stop of equipmentCCPS G-22CCPS G-27CCPS Y-28OSHA1910.11917.19.20.544.EQUIPMENTTable 4.1: Reactors and VesselsNo.Concern/IssueOverpressure1.Overfill, resultingin vesseloverpressure.•Use open vent or overflow line discharged to asafe location•Install level device interlocked to prevent overfill•Install independent high level alarm with instruc-tions to prevent overfilling•Prepare and implement instructions to monitorlevel and fill rate during transfer and verify thatvessel has sufficient free board prior to transfer•Install emergency relief device (ERD)•Design vessel to accommodate maximum supplypressure2.Inadvertent or•Ensure that utility connections do not exceeduncontrolledpressure rating of vesselopening of high•Use incompatible utility couplings to preventpressure utilityconnections of high pressure utilitiessystem resulting in•Use fixed piping and adequate labeling to avoidvesselcoupling errorsoverpressure.•Install mechanical flow restriction (e.g., restric-tion orifice) of utility with open vent on vessel•Provide pressure control regulator and pressurerelief device•Provide sensor interlocked to isolate utilitypressure•Install pressure indication and alarm•Design vessel to accommodate maximum utilitypressure•Install emergency relief device/system on vesseland/or utility line•Install emergency relief/device/system on utilityservice set at or below vessel pressure ratingASME VIIICCPS G-11CCPS G-41ISA S84.01API 2350ASME VIIIPotential Solutionsand Control MechanismsAdditionalResourcesTable 4.1: Reactors and Vessels55AdditionalResourcesNo.Concern/IssueOverpressure3.Blockage of reliefdevice by solidsdeposition (poly-merization, solidi-fication). Possibleloss ofoverpressureprotection.Potential Solutionsand Control Mechanisms•Develop and implement procedure to removeand inspect relief device after suspectedoperation•Perform visual inspection and scheduledreplace-ment of relief devices periodically•Provide flow sweep fitting at inlet of reliefdevice•Heat trace/insulate vessels and critical piping, asneeded•Design to accommodate maximum expectedsystem pressure•Provide a periodic or continuous flush of reliefdevice inlet with purge fluid•Use rupture disks alone or in combination withsafety valves with appropriate rupture disk leakdetectionASME VIIICCPS G-114.Ignition of•Use nonflammable solventsAPI 2028flammable•Provide ignition source controls (e.g., permanentNFPA 30atmosphere ingrounding/bonding, nonsplash filling, etc.)NFPA 68vessel vapor space.•Store or process material below its flash pointNFPA 69•Use instrumentation that does not provide anignition source, and/or minimizes the probabilityof air ingress into vessel.•Inert vapor space•Install oxygen analyzer with alarm•Install flame arrester in vent path•Provide emergency purge and/or isolation acti-vated by detection of flammable atmosphere orhigh oxygen concentrations•Install deflagration pressure relief•Design vessel to accommodate device/systemmaximum deflagration pressure56Potential Solutionsand Control Mechanisms4.EQUIPMENTNo.Concern/IssueUnderpressure5.Uncontrolled con-densation/absorp-tion of vaporphase componentresulting invacuum creationinside vessel.AdditionalResources•Design vessel to accommodate maximumvacuum (full vacuum rating)•Use blanketing gas pressure control system tominimize vacuum•Install vacuum relief system•Blanket condenser with inert gas•Insulate equipment to mitigate effect of ambienttemperature changes, e.g., thunderstorm•Interlock cold liquid feeds with heat source (e.g.,distillation column)AGA XK0775ASME VIIIFMEC 7-596.Excessive liquidwithdrawal rateresulting in possi-bility of pullingvacuum.•Design vessel to accommodate maximumvacuum (full vacuum rating)•Provide open automatic/manual vent or install arestriction orifice•Size pump to limit withdrawal rate•Interlock pump rate to vessel pressure•Interlock pressure or pump power to shutoffpump•Use inert gas blanket to minimize vacuum•Install vacuum relief systemASME VIIICCPS G-30FMEC 7-59High Temperature7.High temperaturematerial fed tovessel. Tempera-ture excursionoutside the safeoperating enve-lope resulting in arunaway reaction.•Install high temperature alarm, and interlock toactivate cooling or shut off feeds at desiredtemperature•Install interlocks to prevent deadheading ofpumps (e.g., high temperature shut-down)•Develop and implement operating instructions tocontrol feed temperature and shut off feed whentemperature rises above a certain level•Provide emergency relief device (ERD)•Design system to accommodate maximumexpected temperature and pressureASME VIIICCPS G-11Table 4.1: Reactors and Vessels57AdditionalResourcesNo.Concern/IssueHigh Temperature8.Potential Solutionsand Control MechanismsASME VIIILoss of effective•Provide back-up source of coolingcooling. Tempera-•Measure, alarm and/or interlock low coolantCCPS G-11ture excursionflow, low coolant pressure, high differential tem-CCPS G-41outside the safeperature between inlet and outletoperating envelop.•Low coolant flow or pressure or high reactortemperature to actuate secondary coolingmedium via separate supply line•Use large inventory of naturally circulating, boil-ing coolant to accommodate exotherm (e.g.,refluxing solvent)•Use antifouling agents and corrosion inhibitorsin heat transfer systems•Perform functional test of cooling system priorto batch reaction addition•Ensure automatic isolation of feed on detectionof loss of cooling•Install automatic or manual activation of bottomdischarge valve to drop batch into a dump tankwith diluent, poison, or inhibitor, or to an emer-gency containment area (May not be effective forsystems such as polymerization reactions wherethere is a significant increase in viscosity.)•Provide for automatic or manual addition of dil-uent, poison, or inhibitor directly to reactor•Install emergency relief device (ERD)•Design system for maximum expected pressureReaction/Ignitionor thermal decom-position due tohigh temperatureat unwetted inter-nal heating ele-ment surface.Possibility of run-away reaction,vapor phase defla-gration or thermaldecomposition.•Limit temperature of heating medium•Use split heating/cooling system to eliminate heattransfer to unwetted surface•Heat with sparged steam/tempered water•Avoid splashing of material onto unwetted heat-ing surface•Use external heating system with processrecirculation•Implement operating instructions to maintainliquid level above heating surface at all times•Install automatic level control with low levelalarm and shutdown of liquid withdrawal systemto ensure liquid is above heating surface at alltimes•Provide inert vapor space to prevent vapor phasedeflagrations•Install emergency relief device (ERD)•Design system to accommodate maximumexpected temperature and pressureASME VIIICCPS G-11CCPS G-30FMEC 7-59NFPA 68NFPA 699.58Potential Solutionsand Control Mechanisms4.EQUIPMENTNo.Concern/IssueHigh Temperature10.High reactor tem-perature due tofailure of tempera-ture control. Tem-perature excursionoutside the safeoperatingenvelope.AdditionalResources•Limit temperature of heating media and provideautomatic shut-off of heat above a presenttemperature•Provide independent interlocks to shut-off heat-ing media on high temperature•Provide emergency cooling•Provide automatic or manual activation ofbottom discharge valve to drop batch into adump tank with diluent, poison, or inhibitor, orto an emergency containment area•Provide automatic or manual addition of diluent,poison, or inhibitor directly to reactor•Design system to accommodate maximumexpected pressure•Install emergency relief device•Ensure proper mixing in reactor•Monitor exterior wall temperature with infraredoptical detection system, and operating instruc-tions for operator response if high temperaturesignal occurs•Install high temperature sensors interlocked toshut down reactor•Provide automatic or manual introduction ofquench fluid on detection of high localtemperature•Shutdown/depressure reactor upon detection ofhigh temperature•Design system to accommodate maximumexpected pressure and temperature•Install emergency relief device•Ensure utility temperature does not exceed run-away reaction temperature or vessel maximumdesign temperature•Provide high/low temperature alarms to shut offfeed•Monitor heat removal rate or coolant outlettemperature•Provide adequate heat transfer surface area ortemperature gradient (keeping in mind that fluidproperties and temperature change as the reac-tion progresses)•Provide agitator monitoring to alert operators•Design to allow for internal and external foulingresulting in reduction of heat transfer capacityASME VIIICCPS G-11CCPS G-22CCPS G-2311.Hot spot developsin reactionmedium. Temper-ature excursionoutside the safeoperating enve-lope, possiblyresulting in a run-away reaction ordecomposition.Potential mechani-cal failure of reac-tor wall.CCPS G-11CCPS G-12CCPS G-23CCPS G-36Fisher 199012.Inadequate heattransfer rates,(e.g., loss of agita-tion in jacketedvessels). Undesir-able reactor tem-perature leading toeither too high ortoo low reactionrates.CCPS G-23Table 4.1: Reactors and Vessels59AdditionalResourcesNo.Concern/IssueHigh Temperature13.Potential Solutionsand Control MechanismsExternal fire expo-•Fireproof insulation (limits heat input)sure resulting in•Slope-away diking with remote impounding ofrunaway reactionspillsand/or system•Locate batch operation outside of affected fireoverpressure.zone•Provide safe separation distances•Install fixed fire protection and alarms, watersprays (deluge), and/or foam systems activated byflammable gas, flame, and/or smoke detectiondevices•Install fire safe bottom valves•Install fire safe valves on major solvent lines•Install remote shut off of fuel sources•Eliminate points of leakage (flanges, hoses).Replace with fixed/welded pipes•Move flammable material storage away fromvessel (e.g., pallets, etc.)•Eliminate sources of fuel•Blank unused lines at switching station•Provide emergency cooling activated by externalfire (e.g., fusible link, plastic tubing)•Install depressurizing system•Install emergency relief device•Develop emergency response planHigh temperature•Limit agitator power input and provide properdue to excessiveimpeller designagitator shaft work•Limit shaft speedresulting in high•Monitor shaft speedreaction rates.•Provide adequate cooling system•Design system to accommodate maximumexpected temperature, and pressureHot bearing/sealscausing ignition offlammables invapor space.Localized initia-tion and possiblepropagation ofdecomposition orloss ofcontainment.•Develop alternative agitation methods toeliminate shaft seal as a potential hot spot•Train operators to visually check mechanical sealfluid on regular basis•Inert vapor space•Provide nitrogen buffer zone around seal usingenclosure around seal•Install mechanical seal fluid reservoir low levelsensor with alarm•Installvibrationortemperaturesensorwithalarm•Install emergency relief device (ERD)•Provide adequate preventive maintenanceCCPS G-11FMEC 7-44NFPA 1NFPA 11NFPA 15NFPA 16NFPA 25NFPA 68NFPA 69NFPA 204NFPA 704OSHA1910.119. 10614.CCPS G-7CCPS G-29Lees 199615.CCPS G-22CCPS G-29CCPS G-39CCPS G-4160Potential Solutionsand Control Mechanisms4.EQUIPMENTNo.Concern/IssueLow Temperature16.Low ambient tem-perature resultingin embrittlementand/or mechanicalfailure of reactor.Mixing17.Excessive mixingof reactants orimpurities whichpromotesemulsification.Poor phase separa-tion resulting inproblems in subse-quent processingsteps or in down-stream equipment.Viscosityofreactorcontentsincreasesdramaticallywiththeextentofreac-tion.Mixingbecomesmoredif-ficultasreactionproceeds.Thismayleadtohotspotsduetoinsufficientmixingorinade-quateheattransferratesresultinginrunawayinitiation.Incompletely sub-merged agitatorimpeller resultingin excessive forceson reactor walland heads. Possi-ble loss ofcontainment.AdditionalResources•Monitor temperature•Provide adequate heating•Design system to accommodate minimumexpected temperature•Provide freeze protection/heat tracingCCPS G-23CCPS G-29Lees 1996•Limit agitator power input and provide properimpeller design•Return process to pilot or development to rede-sign process to eliminate or minimize thisproblem•Limit shaft speed•Monitor shaft speed•Test for phase separation•Install de-emulsifiers•Design process to work within agitatorlimitations•Design agitator to account for property varia-tions with reaction progress•Monitor shaft speed•Design system to accommodate maximumexpected pressure and temperature•Provide emergency relief device•Monitor viscosity•Add diluent to reduce viscosity•Monitor agitator power input•Monitor agitator power input•Designagitatortobestableduringfillingandemp-tyingoperation(e.g.,stiffershaft,footbearing)•Install low level shutoff preventing further liquidwithdrawal from vessel•Install low level alarm with interlock to automat-ically shutdown the agitator•Provide instructions to manually stop agitation atpredetermined level in vesselCCPS G-29Lees 199618.CCPS G-29Kletz 1991Lees 199619.CCPS G-29Kletz 1991Lees 1996Table 4.1: Reactors and Vessels61AdditionalResourcesNo.Concern/IssueMixing20.Loss of agitationcausing stratifica-tion of immisciblelayers. Insufficientmixing of reac-tants results inunwanted accumu-lation of unreactedreactants. Possibil-ity of runawayreaction uponresumption ofagitation.Potential Solutionsand Control Mechanisms•Use compatible/mutually soluble materials•Provide agitator monitor (shaft speed, load, etc.)to alert operators.•Implement procedures to dispose of unreactedmaterials•Implement procedure and/or back-up equipmentfor dealing with imminent danger relating to agi-tator failures•Interlock agitator power consumption to cutofffeed of reactants or catalyst or activate emer-gency cooling•Provideemergencypowersupplybackuptomotor•Porvide automatic or manual actuation ofbottom discharge valve to drop batch into adump tank with diluent, poison, or inhibitor, orto an emergency containment area•Provide in-vessel agitation (velocity) sensor withalarm•Activate inert gas sparging into reactor liquid toeffect mixing•Provide emergency relief device (ERD)•Design system to accommodate maximumexpected pressureCCPS G-11CCPS G-23CCPS G-29Kletz 1991Lees 1996Runaway Reaction21.Reactor contentsinadvertentlyadmitted toupstream feedvessel. Possibilityof reaction inpiping and vessel.•Design upstream system to accommodate maxi-mum expected pressure•Provide positive displacement feed pump insteadof centrifugal pump or pressurized transfer•Elevate feed vessel above reactor•Provide check valve(s) in feed line (secondarycontrol)•Provide for automatic/manual closure of isola-tion valve(s) in feed line on detection of low orno flow•Provide for automatic/manual closure of isola-tion valve(s) in feed line on detection of reversepressure differential in feed line•Install surge pot between feed vessel and reactorto minimize effects of inadvertent mixing•Install emergency relief device (ERD) on feedvessel or feed line•Feed through vessel top with antisiphon devicein feed line•Utilize double block and bleed pipe and valvingsystemCCPS G-11CCPS G-23CCPS G-29Kletz 1991Lees 199662Potential Solutionsand Control Mechanisms4.EQUIPMENTNo.Concern/IssueRunaway Reaction22.AdditionalResourcesCorrosion prod-•Understand process and do not use materials ofucts lead to cataly-construction that may lead to problemssis of unwanted•Use corrosion inhibitorreaction.•Implement corrosion monitoring and correctionprogram•Implement mechanical integrity programASME VIIICCPS G-7CCPS G-11CCPS G-22CCPS G-29CCPS G-56•Upgrade material of construction or use resistantKletz 1991liner•Implement procedure for testing liner with con-Lees 1996tinuity meter•Provide emergency dump of reactor contents.•Design system to accommodating maximumexpected pressure•Install emergency relief device (ERD) (UPSG-11)•Ensure that pickling or passivation of the systemis complete prior to starting the system23.Corrosion ofequipment andpiping. Possibleloss ofcontainment.•Use less corrosive chemistry (inherently saferprinciples)•Consider addition of corrosion inhibitor•Consider corrosion testing before design•Use corrosion resistant materials of construction•Use resistant liner•Consider procedure for testing liner•Consider use of protective coatings and paintson exterior•Design vessel with double wall and inert spacebetween walls for sampling•Implement scheduled nondestructive testing atkey points to monitor corrosion as part of amechanical integrity program•Evaluate potential for external corrosion fromenvironmental factors such as chloride bearinginsulation, chemical spills, sea mist, road salt,etc.CCPS G-29CCPS G-32CCPS G-41Table 4.1: Reactors and Vessels63AdditionalResourcesNo.Concern/IssuePotential Solutionsand Control MechanismsLoss of Containment24.Loss of sealingCCPS G-23•Circulate vessel contents via external, seal-lessfluid for vessel agi-pumptator seal. Possible•Use double or tandem mechanical seal with inertseal failure andseal fluidemission of flam-•Include requirements for operators to visuallymable or toxiccheck seal fluid reservoir levels on a regular basisvapors.in written operating procedures•Provide seal fluid reservoir with low level sensorand alarm•Install flammable and/or toxic vapor sensorswhere needed•Include operator emergency response to indica-tions of a seal leak in written operatingproceduresPhase Separation in Vessel25.Missing Interface:wrong materialsent to next stepwrong materialsent to wastetreatment•Check both phase layers before proceeding (e.g.,add water to “aqueous” phase and/ornonmiscible phase to identify properly)•Analyze samples of each phase at critical steps•Provide drain value with level interphase shutoff644.EQUIPMENTTable 4.2: CentrifugesNo.Concern/IssueOverpressure1.Centrifuge ventsystem blocked,(e.g., flooding ofeffluent collectingline, freezing,polymerization,and accumulationof solids).•Implement routine checks of vent lines forplugging•Monitor pressure drop across vent system (e.g.,local indication, alarm or interlock)•Eliminate sources of pressure drop by redesign•Check for solid formation in vent condensersoperating below freezing point•Implement thawing cycle•Heat trace vent line (e.g., electrical, steam,glycol)2.Gas pressurizedfeedoverpressurizescentrifuge systemwhen feed vesselempties.•Monitor tank level and provide interlock forfeed shut-off•Use alternate fluid delivery system (e.g., pump)•Limit delivery gas pressure to maximum safeworking pressure of downstream system (e.g.,pressure regulation)•Restrict feed flow rate to be consistent with ventcapacity•Ensure adequate vent capacity for maximumpossible gas flow3.•Provide level switches for effluent collectionBlocked liquidvesselseffluent line result-ing in flooding.•Provide high level alarm in liquid effluent line•Implement preventive maintenance checks4.Blockage of liquideffluent line dueto closed valves,results in floodingof basket andoverflow frombasket to solid col-lection system inbase. Possibility ofliquid spill.•Monitor pressure drop across vent system (e.g.,local indication, alarm or interlock)•Interlock valve in feed line to centrifuge•Equipment/line-up checks•Remove unnecessary valves•Seal valves openKletz 1991Lees 1996Potential Solutionsand Control MechanismsAdditionalResourcesTable 4.2: Centrifuges65Potential Solutionsand Control MechanismsAdditionalResourcesNo.Concern/IssueUnderpressure5.Exhaust systemintroduces a nega-tive pressure in thecentrifuge, canintroduce air intocasing resulting inflammableatmosphere.High Temperature6.Hot feed(increasesfire/explosion riskwith flammablesolvents).•Maintain nonflammable atmosphere (e.g., inertgas purging)•Maintain integrity of gaskets and seals•Check mating faces for corrosion/unevennessparticularly on clad components•Use gaskets compatible with materials beingprocessedNFPA 69•Provide and maintain an automated inertingsystem—oxygen concentration or pressurecontrolled•Eliminate leakage sources (fumes/air)•Use alternative solvents (nonflammable or lessflammable)•Reduce feed temperature and/or monitor tem-perature of feed and interlock with feedshutdownNFPA 697.Bowl or shaftbearings runninghot. Possibility ofignition of vaporor thermal decom-position of thematerial.•Use sealed or purged bearings (to stop ingress ofsolvent)•Establish optimal gearing lubrication program•Introduce feed after centrifuge reaches desiredspeed to prevent solvent from reaching bearings•Monitor bearings for excess (high) temperature.•Provide and maintain an automated inertingsystem—oxygen concentration or pressurecontrolledFMEC 7-59NFPA 69Runaway Reaction8.Centrifuging ofunstable material,shock sensitivematerial couldresult indecomposition.•Test material for impact/shock sensitivity andthermal hazards•Use alternate (low energy) separation process forshock sensitive/unstable materialCCPS G-1366Potential Solutionsand Control Mechanisms4.EQUIPMENTNo.Concern/IssueRunaway Reaction9.Multiple feeds tosingle machine,two feeds open atonce. Incompati-ble materials comein contact, possi-bly leading to run-away reaction.Corrosion10.AdditionalResources•Eliminate interconnections•Interlock feed valves so only one can be open•Install three-way valve•Implement appropriate operating proceduresand trainingCCPS G-15CCPS G-32Failure of clad-•Implement routine inspectionsding, allowing sub-•Implement periodic nondestructive testingstrate to beexposed, leadingto corrosion andpotential failure.Inappropriatematerials of con-struction lead tocorrosion andpotential failure.•Select compatible materials of construction forthe specific process•Change process parameters (e.g., different acid,reduce temperature). Evaluate changes with testcoupons off-lineCCPS G-711.Dillon 1992Loss of Containment12.Solvent/fume leak-•Maintain integrity of gaskets and sealsage from casing•Use gaskets compatible with process materialsjoints resulting in•Check mating faces for corrosion/unevenness,loss ofparticularly on clad componentscontainment.•Use bottom unloading or inverting (basket)Loss of contain-ment during solidsmachinesdischarge.•Provide dump interlock to ensure material istransferred to safe location•Install flexible containment around dischargeopening•Enclose centrifuge in self-contained room orenclosure13.Table 4.2: Centrifuges67Potential Solutionsand Control MechanismsAdditionalResourcesNo.Concern/IssueLoss of Containment14.Leakage or failure•Use materials of construction compatible withof flexible connec-processtions between•Implement routine inspections, monitoring andcentrifuge andpreventive maintenance programsreceiving•Design flexible connections and their attachmentcontainer.methods to accommodate expected process pres-sures (positive and negative), system movementsand vibrationsLids and/or inspec-•Interlock so that it is not possible to operate cen-tion ports openedtrifuge if lids and/or inspection ports are openwhile in operationleading to loss ofcontainment, lossof inerting, opera-tor exposure.Ignition Sources16.Static electricitygeneration inmachines due tobowl rotation orhigh feed velocity.•Usealternatesolventwithreducedstaticpotential•Use conductive materials of construction•Add antistatic agent to nonpolar solvent•Check conductivity prior to feeding•Use static dissipating linings if applicable•Use unlined machine with adequate corrosionresistance; If lining is required, it should beconductive•Provide adequate bonding and grounding•Use ant-static drive belt•Reduce linear flow velocities to eliminate staticcharge buildup during feed•Provide oxygen monitored inerting•Bowldriveshaftrequiresgroundingotherthanthroughgearbox/bearings(e.g.,brushes,sliprings)17.Foreign bodiesembedded in cakecause heat/sparksduring removal(plowing out).•Provide captive retention of tramp metal inupstream equipment (e.g., magnetic separators,scalping screens)•Install coarse filter in feed line•Minimize tramp metal generation at the source(e.g., lock nuts, washers)BS5958FMEC 7-59NFPA 77Pratt 199715.68Potential Solutionsand Control Mechanisms4.EQUIPMENTNo.Concern/IssueIgnition sources18.Loose or mis-placed internalhardware causesheat/sparks duringplowing out.Loose drive beltsgenerating fric-tional heat/staticelectricity.Hot runningbearings.AdditionalResources•Preventative maintenance and operator prestartchecklistCCPS G-2219.•Preventative maintenance checks, tightness andprotection from contaminants•Check belt tension•Preventive maintenance•Monitor bearings temperature•Purging and sealing to keep solvents out, if sol-vent (even vapor) exposure is possible•Use improved bearing lubricantCCPS G-2920.CCPS G-29Fires/Explosions21.See ignitionsources, all thesecan lead to fire orexplosion.Operator Exposure22.Operator exposure•Use bottom unloading or inverting (basket)during solids dis-machinescharge and manual•Design flexible containment around dischargeremoval residualopeningheel.•Enclosecentrifugeincontainedroomorenclosure•Use nitrogen knife to scrape centrifugeGeneral23.Vibration duringplowing out—canlead to prematureequipment failureand a potentialignition source—see above.•Check plow and linkage for loose compo-nents/wear•Sharpen plow or use serrated blade for hardenedheels•Manually remove heel more frequently•Plow at lower bowl speed•Advance plow more slowly•Make sure plow system is well damped•Avoid air actuated plows•Avoid use of full depth plows with hard cakes•Use nitrogen knife to scrape centrifuge•Oxygen monitored inerting system•Explosion suppression devicesTable 4.2: Centrifuges69Potential Solutionsand Control MechanismsAdditionalResourcesNo.Concern/IssueGeneral24.Running unbal-anced, vibrationdue to worn bear-ings or othermechanical prob-lem such as prod-uct accumulationbehind filterscreen.Running unbal-anced—vibrationdue to unevenfeeding.•Preventive maintenance and operator checklistinspections•Use effective vibration monitor/shutdown device25.•Redesign feed distributor•Feed at different bowl speed (usually slower)•Install effective vibration monitor/shutdowndevice•Adjust feed rate to get uniform distributionCCPS G-23CCPS G-29CCPS G-3926.External corrosion•Implement mechanical integrity programof high-energy•Implement proper selection of material ofequipment. Lossconstructionof containmentand damage due toflying debris.Continued feedafter basket is full.•Install automatic cut-off (weight activated)•Monitor process27.28.•Interlock feed to bowl rotationLiquid feed con-tinues after basketof centrifuge stopsspinning.704.EQUIPMENTTable 4.3: DryersNo.Concern/IssueGeneral1.Inadequate venti-lation in ducts dueto partial obstruc-tions or closeddampers leadingto creation offlammable atmo-sphere. Possibilityof fire/explosion.•Design dampers so that system will handle theminimum safe ventilation rate at maximumdamper throttlingAPI 2028API RP 750Potential Solutionsand Control MechanismsAdditionalResourcesBossart 1974•Provide damper mechanical position stop to pre-CCPS G-11vent complete closure of damperCCPS G-22•Eliminate ignition sources within the ductwork•Bond and ground ducts and equipment•Eliminate flammables, wherever possible•Use inert atmosphere•Design ventilation system to keep flammableconcentration below lower flammable limit•Install on-line flammable gas detection and acti-vation of inerting system•Provide automatic sprinkler protection•Install deflagration vents•Provide automatic isolation of associated equip-ment via quick closing valves•Install weak sections in piping and duct work toprovide overpressure relief•Design system to accommodate the maximumexpected deflagration pressure, where practical•Use prescrubbers/condensers/kilns to reduce loadin ductCCPS G-29CCPS G-36CCPS G-41FMEC 7-43FMEC 7-59NFPA 13NFPA 15NFPA 68NFPA 69SFPE 19982.Batch dryer opera-tion resulting in ahigh peak evapo-ration rate offlammable solventcausing buildup offlammables. Possi-bility offire/explosion.General•Inert/purge dryerFMEC 7-43•Design ventilation system to handle the peak sol-FMEC 7-59vent evaporation rateSFPE 1998•Replace flammable solvent (e.g., water based)•Develop and implement system and operatingprocedure designed to allow for unsteady evapo-ration rates3.Inadequate circu-lation in equip-ment causingaccumulation offlammable pock-ets. Possibility offire/explosion.•Design so that natural circulation is sufficient toprevent accumulation of flammables•Eliminate flammable solvent (e.g., water-based)•Design system to accommodate maximum defla-gration pressure, where practicalACGIH 1986CCPS G-23CCPS G-29CCPS G-39CCPS G-41Table 4.3: Dryers71Potential Solutionsand Control MechanismsAdditionalResourcesNo.Concern/IssueGeneral4.Premature shut-•Design so that natural circulation is sufficient todown of fans/ven-prevent accumulation of flammables and/or cre-tilation systemation of hot spotsimmediately fol-•Design system to accommodate maximum defla-lowing shutdowngration pressure, where practicalof heat input(prior to sufficient•Use postventilation interlocks and/or operatingprocedures to keep fans running for a sufficientcooling) resultingtime after shutdown of heating systemsin hot spots andflammable pockets(dryers, carbonbeds, thermal oxi-dizers). Possibilityof subsequent igni-tion resulting infire or explosion.Production of finepowder duringauxiliary process-ing. Possibility of adust ordust/hybridexplosion.•Operate below minimum oxygen concentration•Practice good housekeeping•Grind/blend under inert atmosphere•Provide damage limiting construction•Design system to accommodate maximum defla-gration pressure, where practicalCCPS G-11CCPS G-23CCPS G-39NFPA 68NFPA 695.AGA XK0775CCPS G-23CCPS G-41Eckhoff 1997FMEC 7-59Lees 1996•Maintain inlet temperature of heating medium toNFPA 69equipment sufficiently below the minimum igni-NFPA 654tion temperaturePalmer 1973•Eliminate flammable solvent6.Drying thermallyunstable chemi-cals: thermaldecompositionresulting in vesseloverpressure orrupture.•Control temperature of heating media belowexpected initiation temperature•Use isothermal aging tests to monitor stability atdesired drying temperatureAPI RP 750CCPS G-23CCPS G-29CCPS G-30•Use inert atmosphere/purge to eliminate combus-CCPS G-41tion that could serve to initiate bulk thermalLees 1996decomposition•Screen chemicals to be dried for thermal stabilityNFPA 654•Evaluate and design for pressure consequences ofNFPA 86thermal decompositionPalmer 1973•Evaluate potential for solid phase deflagration(Continued on next page)72Potential Solutionsand Control Mechanisms4.EQUIPMENTNo.Concern/IssueGeneral6.(Continued)AdditionalResources•Eliminate “tramp metal”, broken parts, and“lumping” materials in dryer that may causelocalized overheating (particularly agitated panand auto-filter dryers)•Evaluate heating due to sustained agitation inagitated pan dryers•Use alternate drying method (ex. vacuum dryinginstead of atmospheric drying; vacuum traydryer, freeze drying, cryogenic CO2drying,instead of vacuum rotary dryer) where materialis subdivided in multiple locations•Implement preventive maintenance on bearingsfor rotary, autofilter, and agitated pan dryers•Monitor temperature of material being dried byinfrared, resistance temperature device, (RTD)etc.•Monitor heating media inlet and outlettemperature7.Vapor–air defla-gration insidedryer: thermaldecompositionresulting in vesseloverpressure orrupture.Material sent tonext step too hotfrom dryer:•thermally unsta-ble materialleading toviolentdecomposition•combustiblematerial leads tofire/explosion indownstreamequipment.•Use inert atmosphere/purgeNFPA 86•Evaluate and design for pressure consequences ofNFPA 654thermal decompositionNFPA 69•Evaluate potential for solid phase deflagration•Design system to accommodate the maximumexpected deflagration pressure•Cool material adequately before emptying fromdryer8.See also Drumming Equipment (Table 4.7)Table 4.4: Batch Distillation and Evaporation73Table 4.4: Batch Distillation and EvaporationNo.Concern/IssueGeneral1.Removal of liquidfrom phase that isa known thermaldecompositionhazard (“strip-to-dryness”), i.e.liquid/solid levelfalls below tem-perature sensingdevice leading tooverheating ofthermally unstablematerial resultingin decomposition.•Consider downstream processing that does notrequire that the intermediate be stripped todryness•Use vacuum distillation to obtain lower boilingpoint of solvent to allow lower distillationtemperatureAPI RP 750CCPS G-13CCPS G-23CCPS G-29CCPS G-30Potential Solutionsand Control MechanismsAdditionalResources•Consider co-distillation (replace one liquid withCCPS G-41another in portionwise distillation) or azeotropicCronin 1987distillationEckhoff 1997•Consider incorporating inert material to act asNFPA 36heat sinkNFPA 491•Implement in-process analysis to determine ifthermally unstable component is consumed orconverted•Provide temperature measurement in bottom ofvessel to insure temperature monitoring•Limit maximum utility temperature by choosingdifferent heating/cooling medium (e.g.. temperedwater in atmospheric loop vs. high pressuresteam)•Provide redundant independent temperaturemonitoring instrumentation2Removal of liquid•Evaluate thermal stability characteristics of reac-from phase that istion mixturean unknown ther-•Conduct thorough evaluation of process modifi-mal decomposi-cation using management of change reviewtion hazard (dueprocedureto contamination,unreacted thermalSee also item 1 abovedecompositionhazard material, orchange in startingmaterial) leadingto overheating ofthermally unstablematerial resultingin decomposition.CCPS G-13CCPS G-22CCPS G-29CCPS G-30CCPS Y-28Cronin 198774Potential Solutionsand Control Mechanisms4.EQUIPMENTNo.Concern/IssueGeneral13.Freezing/pluggingof condenser, withcontinued heatingor process feed,leading tooverpressure ofvessel.Drawing distillateback into the dis-tilling vessel.AdditionalResources•Use cooling medium that will not cause freezing(e.g., tempered water instead of chilled water)•Monitor pressure drop across condenser•Provide “thawing cycle”•Provide high pressure interlock to shutdownheating and/or process feed•Do not use sub-surface inlet to receiver fromcondenser•Use “weep-hole” (siphon break) in sub-surfaceinlet piping•Ensure valves are in correct position•Incorporate batch distillation into written proce-dure for the process•Fill vacuum vapor space of vessel with inert gasprior to cool down•Install check valve in distillate discharge lineAPI RP 750CCPS G-10CCPS G-294.API RP-75Bossart 1974CCPS G-10CCPS G-22CCPS G-25CCPS G-27CCPS G-29FMEC 7-59API RP 750CCPS G-6CCPS G-13CCPS G-27CCPS G-29CCCPS G-1CCPS G-6CCPS G-13Cronin 19875.Inadequate•Sample and analyze prior to proceeding to nextremoval of solventstepleading tounwanted reactionin downstreamequipment or insubsequent steps.Co-distillation•Evaluate isothermal aging characteristics of ther-leads to longmally unstable components at the maximumperiod of timeexpected utility temperatureunder heat result-•Consider using the same solvent in the next steping in exceeding(i.e. eliminate the co-distillation)the isothermalaging characteris-tics for a thermallyunstable materialwhich leads tothermal decompo-sition andoverpressure ofthe vessel.6.Table 4.5: Process Vents and Drains75Table 4.5: Process Vents and DrainsNo.Concern/IssueGeneral1.Low point traps(pockets) in ventlines.•Design vent lines to prevent low point traps(pockets)•Provide adequate drainage•Design and maintain drainage system for trappedsections of vent lines2.Prescrubbing(vessel containingscrubber solutionbetween vacuumsource and batchvessel). High con-centration ofoff-gases resultingin overpoweringabatementequipment.•Provide subsurface addition to prevent “bypass-ing” of prescrubber solution•Implement pH monitoring to determine usefullife of scrubbing solution•Consider the thermal effects of reaction mixturetransfer to prescrubberCCPS G-11CCPS G-22CCPS G-23Potential Solutionsand Control MechanismsAdditionalResourcesAPI RP 750CCPS G-13CCPS G-22CCPS G-23CCPS G-25•Provideagitation,coolingjacket,andtemperatureCCPS G-29controlforprescrubbertoimproveoperationCCPS G-41•Install high temperature interlock on dischargeof condenser to shutdown reactor and initiateemergency cooling•Use “large volume” prescrubber to minimizepotential for overcoming and/or by-passing itFMEC 7-43Hendershot1987NFPA 363.Bringing scrubbing•Provide vacuum break to prevent siphoning ofsolution back intoprescrubber solution back to reactorreactor.Uncontrolledrelease of flamma-ble, toxic, orenvironmentallydetrimental vaporsfrom atmosphericvents.•Route to scrubber, quench, or other controldevice•Install differential pressure or flow monitoringdevice to indicate flow into/out of vent•Use conservation vent to minimize releases•Provide flame arrester in/on vent line•Ensure vents relieve to a safe location. If ventedto atmosphere, ensure proper classification andcontrolled accessCCPS G-3CCPS G-4CCPS G-11CCPS G-13CCPS G-23CCPS G-294.5.Drawing reactionmixture intovacuum system orscrubbing system.•Provide empty vessel between vacuum source orscrubbing system and reaction vessel to act asliquid trap•Investigate incompatibility of various processstreams going to the same vacuum or scrubbingsystem•Monitor vacuum level between source and reac-tion vesselCCPS G-13CCPS G-23CCPS G-30764.EQUIPMENTTable 4.6:Transferring and Charging EquipmentNo.Concern/IssueGeneral1.Temporary con-nections offer a lotof flexibility tooperations but alsocreates concernsabout increasedoperator exposure,loss of contain-ment, and the abil-ity to add theincorrect materialor charge to theincorrect vessel.Open manway/addition portresults in releaseof flammable,toxic, or environ-mentally detri-mental vapors.Overpressure3.Overfill resultingin vesseloverpressure.•Use sensors/alarm/interlocks (i.e., weight, levelsensors)•Ensure vessel has room for transfer•Install high-high level switch in receiving vesselinterlocked to feed and/or emergency dump4.Excessive fill rate.•Install flow restriction orifice in fill line•Install fill line control with high flow alarmand/or shutdown•Provide interlock activated by high pressure orhigh flow•Develop and implement procedures to monitorlevel and fill rate during transfer and verify thatvessel has sufficient free board prior to transfer•Provide emergency relief device (ERD)•Design vessel to accommodate maximumexpected supply pressureAPI RP 750CCPS G-3CCPS G-29CCPS G-30API RP 750ASME VIIICCPS G-11CCPS G-22CCPS G-23CCPS G-29DIERS•Use permanent piping, wherever possible•Provide clear labeling on all lines entering andexiting vessels•Provide and require use of personal protectiveequipment (PPE)•Implement appropriate procedures and trainingCCPS G-3CCPS G-10CCPS G-15CCPS G-20CCPS G-22CCPS G-29CCPS G-30CCPS G-32Potential Solutionsand Control MechanismsAdditionalResources2.•Limit opening of manholes•Use localized ventilation (flexible ventilationpick-up close enough to manway/addition portto effectively capture emissions)•Lower batch temperature to 20°C below boilingpoint before openingACGIH1986API std. 653APIstd.2000APIstd.2015CCPS G-29NFPA 328Table 4.6:Transferring and Charging Equipment77AdditionalResourcesNo.Concern/IssueOverpressure5.Incorrect amountscharged.Potential Solutionsand Control Mechanisms•Check for improperly labeled partial containers•Use control devices (flow, level, etc.)•Modify recipe to use whole containers•Modify recipe to use whole pallet or containerAPI RP 750CCPS G-29•Ensure correct amount is on hand before startingCCPS G-226.Pumping of heatsensitive material.Exothermicdecompositionleading tooverpressure.•Design casing to contain decompositionoverpressure•Provide deadhead protection (hydraulic relief)•Use jacketed cooled pumps•Avoid the use of positive displacement pump•Select pump to minimize heat input•Provide high temperature/pressure alarm andshutdown•Provide emergency relief device (ERD)CCPS G-1CCPS G-8CCPS G-11CCPS G-23FMEC-1974Lees 1996NFPA 4967.Decomposition ofheat sensitive pro-cess material dueto heat generatedfrom mechanicalinput (i.e., plug-ging of rotaryfeeders, paddledryers, screwconveyors).•Use equipment types which minimize mechanicalCCPS G-11heat inputCCPS G-28•Install deflagration venting and/or suppressionNFPA 68systemNFPA 69•Eliminate tramp metal in feed to grinder, screw,etc.•Eliminate tramp metal generated due to equip-ment breakageCCPS G-11CCPS G-23CCPS G-29CCPS Y-28NFPA 6548.Pump used for•Design to accommodate for maximum expectedhigher than designpressuredensity fluid ser-•Verify suitability of pump for service; replace ifvice resulting innecessaryhigh discharge•Provide emergency relief device (ERD)pressure.•Provide interlock to shutdown pump on detec-tion of high discharge pressure•Ensure management of change procedures arefollowed•Monitor power and install high currentshutdown78Potential Solutionsand Control Mechanisms4.EQUIPMENTNo.Concern/IssueOverpressure9.AdditionalResourcesPump deadheaded.•Check for downstream closureCCPS G-11•Use minimum flow recirculation lines piped backCCPS G-29to feed vessel•Consider use of internal relief valve as applicable10.Vent system inop-erable or plugged.•Check and open vents by scheduled preventivemaintenance•Monitor flow through vent system; providesteady purge if needed•Make sure vent system is sloped to drain toknock-out pot (separator)•Perform periodic maintenance and inspection11.Inert gas or otherpressure source isopen.•Install a pressure regulator to control sourcepressure•Install pressure indicator and relief valveAPI RP 750CCPS G-11CCPS G-22CCPS G-29AGA-X0775CCPS G-11CCPS G-22CCPS G-2912.Adding volatile•Indication and alarm on high temperaturephase on top of•Interlock additions valves to vessel temperaturehot phase (or viceversa) resulting in•Provide adequately sized emergency relief device(ERD)rapid phase transi-tion and overpres-suring of vessel.Blockage of•Size piping system to maintain minimumpiping, valves orrequired velocity to avoid build-up of solidsflame arresters due•Eliminate flame arrester or use dual (parallel)to build-up offlame arresters with on-line switchingsolids. Potentialcapabilitiesfor system•Remove solids from process stream (knockoutoverpressure.pot, filter, cyclone separator, etc.)•Provide insulation/tracing of piping to minimizesolid deposition (freezing/precipitation)•Provide recirculation line to minimize deposition•Install flush mounted valves•Implement periodic cleaning via flushing, blow-down, internal line cleaning devices (e.g., “pigs”)•Design piping for maximum expected pressure•Install emergency relief devices whereappropriate13.CCPS G-11CCPS G-54DIERSFMEC 1974IRI 1990Lees 1996NFPA 54NFPA 69Table 4.6:Transferring and Charging Equipment79AdditionalResourcesNo.Concern/IssueUnderpressure14.Low pump headpressure.Potential Solutionsand Control Mechanisms•Increase pressure at source•Verify pump design will achieve needed pressure•Check for restrictions in suction and dischargelinesCCPS G-2315.Failure of vacuumsystem controlresulting in possi-bility of vesselcollapse.•Design vessel to accommodate maximumvacuum (full vacuum rating)•Install vacuum relief system•Provide low pressure alarm and interlock toinert gas supply•Select/design vacuum source to limit vacuumcapabilityASME VIIICCPS G-23CCPS G-39High Temperature16.Temperature con-trol failure onlines/equipment.•Perform periodic maintenance and inspection•Install redundant control systemCCPS G-22CCPS G-29CCPS G-1117.Line or equipment•Include hydraulic relief in lineexposed to direct•Provide adequate insulation for solar protectionsun or heat source.•Clear lines after each useLow Temperature18.19.Cold ambienttemperature.Temperature con-trol failure onlines orequipment.Corrosion•Provide insulation, heating, etc.•Check heat tracing•Perform periodic maintenance and inspectionCCPS G-2920.Incorrect/incom-patible materialsof constructionused in transfer-ring/charging lineor equipment.•Review material of construction requirements vs.CCPS G-23existing equipment before changing service•Use corrosion coupons during pilot/develop-ment/scale-up80Potential Solutionsand Control Mechanisms4.EQUIPMENTNo.Concern/IssueCorrosion21.Incorrect concen-trations of mate-rial are chargedresulting in a cor-rosive environ-ment, (i.e.,diluting acid).AdditionalResources•Check label versus process requirements•Check correct step in operating procedure•Label materials, lines pumps and valves•Use staging area•Check labels against batch sheets•Use double check system•Set valves to correct flow path•Use procedures and trainingCCPS G-22CCPS G-29CCPS G-30Hendershot1987Runaway Reaction22.Unwanted reaction•Clean and inspect equipment after each usedue to•Design with compatible materialscontaminants.•Maintain integrity of the system•Design emergency relief system (ERS) for run-away scenario23.Accumulation of•Design system to accommodate maximumreactive materialexpected pressurein section of auxil-•Use inherently safer chemistryiary equipment orpiping. Possibility•Implement on-line measurement (e.g., level, tem-perature, composition) and side draw-off ofof runawayreactive materialreaction.•Eliminate pockets where material couldaccumulate•Design piping and equipment to drain to a safelocation•Provide emergency relief design (ERD)•Provide procedures to clean pipes24.Incorrectchemicals used.•Label materials, lines, pumps and valves•Use staging area•Check labels against batch sheets•Set valves to correct flow path•Use double check system•Use procedures and training•Use different packaging for different chemicalsAPI RP 750CCPS G-3CCPS G-22CCPS G-30CCPS G-33CCPS G-13CCPS G-22CCPS G-23CCPS G-29CCPS G-11CCPS G-23CCPS G-29CCPS G-41Kletz 1991Table 4.6:Transferring and Charging Equipment81AdditionalResourcesNo.Concern/IssueRunaway Reaction25.Charging ther-mally unstablematerial to warmreactor results indecomposition.Poor distributionof solids or liquidcharge. Potentialfor excessive reac-tion rates due tolocalized over-concentrations ofreactants.Potential Solutionsand Control Mechanisms•Install local indication and alarm on hightemperature•Provide emergency coolingCCPS G-2326.•Implement appropriate procedures and trainingCCPS G-22Loss of Containment27.Pump is operatedat a fraction ofcapacity. Possibil-ities of excessiveinternalrecirculation, fre-quent seal andbearing failureresulting in loss ofcontainment.•Match pump capacity to the service•Install minimum flow recirculation line to heatsink to ensure adequate cooling of the pump•Provide interlock to shutdown pump on mini-mum flow indication•Implement procedural controls to avoid operat-ing at too low a flow•Provide deadhead protectionCCPS G-29CCPS G-23CCPS G-2928.Transfer path is•Verify open and clear transfer path before initi-blocked due toating transferclosed valve, blind•Utilize pressure and flow sensorsetc. Pressure isbuilt up in systemand leaks in pipingoccur.Release oftoxic/flammablematerial frompiping due to leak,flange leak, valveleak, pipe rupture,collision, orimproper support.•Implement procedure for line breaking•Select materials of construction for pipes andgaskets to be compatible with all materials to betransferred•Install fireproof/spiral wound gaskets whereapplicable•Install new hose gaskets for each batch connec-tion(Continued on next page)29.API RP 1623ASME B31.3CCPS G-22CCPS G-23CCPS G-24CCPS G-29CCPS G-3982Potential Solutionsand Control Mechanisms4.EQUIPMENTNo.Concern/IssueAdditionalResourcesLoss of Containment29.(Continued)•Maximize use of welded pipe vs. screwed orflanged and minimize use of unnecessary fittings•Avoid use of underground/hidden piping•Use double walled pipe with annular nitrogenpurge and monitoring capabilities•Provide flange shields to prevent operatorexposure•Account for thermal cycling of lines•Use minimum diameter pipe for physicalstrength•Use proper design and location of pipingsupports•Provide physical collision barriers•Provide isolation on detection of high flow, lowpressure, or external leak•Install excess flow valves•Use fusible link fire safe valves for automatic clo-sure under fire conditions•Develop and implement procedural restrictionsto avoid damage (crane restrictions, climbingrestrictions)•Use totalizing meters on each end of line todetect leak•Adhere to design requirements for seismic zone•Perform piping flexibility studies•Install pressure relief for thermal expansion30.•Eliminate hose, use hard pipes wherever possibleDegradation ofhose results in leak•Consider use of higher integrity hose (e.g.,and release ofmetallic braided)toxic/flammable•Use hoses rated for required maximum systemmaterial.pressure and pressure test before use•Periodically replace hoses•Provide excess flow check valve upstream andcheck valve downstream of hose•Isolation based on detection of high flow, lowpressure or external leak•Use fusible link fire safe valves for automatic clo-sure under fire conditions(Continued on next page)CCPS G-22CCPS G-23CCPS G-29Kletz 1991NFPA 30NFPA 70NFPA 30Table 4.6:Transferring and Charging Equipment83AdditionalResourcesNo.Concern/IssuePotential Solutionsand Control MechanismsLoss of Containment30.(Continued)•Provide crush protection (e.g., ramp) whenlaying hoses across roadway•Avoid sharp angle changes in direction•Implement procedure for cleaning hoses andinspection•Use a dedicated hose for each materialtransferred•Install appropriate bonding and grounding withperiodic testing•Select appropriate material of construction•Avoid the use of transfer hoses in hidden areas31.Deterioration ofpipe/hose liningdue to chemicalattack or electro-static discharge.•Use pipe material of construction which does notAPI RP 1632require liningBritton 1999•Use conductive liner to reduce potential for deg-CCPS G-23radation due to static dischargeCCPS G-29•Use thicker liner materialNFPA 69•Limit liquid velocity to minimize static buildupNFPA 77•Perform periodic thickness testing of metal pipewall•Perform periodic process stream analysis formetals content•Ensure proper care is used during lined pipeinstallation32.Piping erosion.•Limit fluid velocityCrane’s FluidFlowHandbookCCPS G-29NFPA 7033.Portable equip-ment and tempo-rary connectionsfor processingreceive more wearthan fixed system.This may lead tohazardous release,ignition orexplosion.•Pressure test connections•Provide manual bonding and grounding•Analyze hazards before using portable equipment•Evaluate procedure for installation/hook-up toensure proper safety is achieved•Provide double protection of quick connects•Follow mechanical integrity program•Conduct process hazards analyses•Implement management of change controls84Potential Solutionsand Control Mechanisms4.EQUIPMENTNo.Concern/IssueAdditionalResourcesLoss of Containment34.Frequent disas-sembly/assemblyof equipmentincreases mechani-cal wear resultingin possible loss ofcontainment.•Follow mechanical integrity program•Implement testing of equipment prior to eachuse or change of service•Implement procedures to verify change ofservice•Interlock procedures to verify safety beforeopening•Ensure maintenance procedures are followed•Select equipment for ease ofassembly/disassembly•Implement procedures for line breaking/cleaning•Provide correct tools for assembly/disassemblyFire and Explosion35.Ignition of con-densed flammablevapor or soliddeposits inductwork/pipingresulting in possi-bility offire/explosion.•Design system to prevent condensation•Design system with smooth surfaces to minimizebuildup of deposits•Eliminate potential points of solids/liquidaccumulation•Implement good housekeeping procedures•Provide for drainage of piping/ducts (e.g.,sloped, low point drains)•Eliminate ignition sources within the ductwork•Provide adequate bonding and grounding•Eliminate flammables or combustibles•Use of inert atmosphere•Design ventilation system to keep flammableconcentration below lower flammable limit•Install on-line flammable gas detection systemthat activates an inerting system•Provide automatic sprinkler system•Use deflagration vents•Design for automatic isolation of associatedequipment via quick closing valves•Design system to accommodate maximumexpected pressure, where practical•Design for operation above dew point or subli-mation pointAPI RP 750CCPS G-11CCPS G-22CCPS G-23CCPS G-24CCPS G-29CCPS G-41Lees 1996NFPA 13NFPA 15NFPA 68NFPA 69CCPS G-29IRI 1990Kletz 1991Lees 1996Table 4.6:Transferring and Charging Equipment85AdditionalResourcesNo.Concern/IssueFire and Explosion36.Electrostatic sparkdischarge and igni-tion during charg-ing of liquids, orduring mixing,cleaning etc.resulting in possi-bility of fire/explo-sion. Excessiveaddition rate(linear flow veloc-ity) can result inelectrostaticcharge. Potentialfor explosion tostart a thermaldecomposition ofreaction mass.Potential Solutionsand Control Mechanisms•Use nonsplash addition methods for liquids (e.g.,API RP2003subsurface addition, addition along the wall,BS 5958etc.)CCPS G-11•Use “antistat” with nonpolar solventsNFPA 13•Ensure that cooling solvent temperature is suffi-NFPA 68ciently low to operate outside flammable limitsNFPA 69•Control velocity/turbulence of liquid addition•Avoid filters on addition lines close to inlet toreduce turbulence and charge generation•Inert vessel and verify safe atmosphere beforecharging•Control humidity in operating area (as humidityincreases, static potential decreases)•Avoid use of nonconductive materials of con-struction for both installed equipment andcharging containers, funnels, etc.•Provide ground indicator with interlock to pre-vent manhole opening if ground connection tosolids container is faulty•Implement procedures for manual groundingand bonding of additions container and funnelto vessel•Ground the operator and provide operator withproper clothing/attire (e.g., conductive shoeswith periodic testing)•Install permanent bonding/grounding of equip-ment system with periodic testing•Install fire/deflagration suppression systemNFPA 70NFPA 77Pratt 199737.Electrostatic sparkdischarge and igni-tion during charg-ing of solidsresulting in possi-bility of fire/explo-sion. Potential forexplosion to starta thermal decom-position of reac-tion mass.•Eliminate addition of materials as solids (e.g.,use slurry)•Consider charging solids before solvents•Charge solids materials by means of a closedsystem (e.g., hopper and rotary airlock, screwfeeder, double-dump valve system, etc.)•Inert vessel and verify safe atmosphere beforecharging•Control humidity in operating area (as humidityincreases, static potential decreases)(Continued on next page)AGA XK0775API RP 2003BS 5958CCPS G-22CCPS G-23CCPS G-29CCPS G-32NFPA 68(Continued)86Potential Solutionsand Control Mechanisms4.EQUIPMENTNo.Concern/IssueFire and Explosion37.(Continued)AdditionalResources•Avoid use of nonconductive materials of con-struction for both installed equipment andcharging containers, funnels, etc.•Avoid use of nonconductive liners in chargecontainers•Provide ground indicator with interlock to pre-vent manhole opening if ground connection tosolids container is faulty•Implement procedures for manual groundingand bonding of solids container and funnel tovessel•Ground the operator and provide operator withproper clothing/attire (e.g., conductive shoeswith periodic testing)•Install permanent bonding/grounding of equip-ment system with testing•Install fire/deflagration suppression systemNFPA 69NFPA 70NFPA 77Pratt 199738.Tramp materialsintroduced intomanway, leadingto impact or fric-tional spark, ignit-ing vapors.•Install scalping screen on vessel charge hatch•Remove tramp materials prior to charging vesselCCPS G-22CCPS G-23CCPS G-2939.Inert gas not pres-•Determine process requirementsent leading to cre-•Implement correct proceduresation of flammable•Install vapor space analyzers with alarmatmosphere.Bossart 1974CCPS G-1CCPS G-22CCPS G-23CCPS G-29CCPS G-32ISARP12.1340.Incorrect electrical•Check area classification and verify that electri-classification forcal equipment is properly ratedequipment or aux-iliary equipment,lighting, etc., pos-sibly leading tounsafe conditions.API RP 500CCPS G-23CCPS G-29NFPA 70NFPA 497Table 4.6:Transferring and Charging Equipment87AdditionalResourcesNo.Concern/IssueFire and Explosion41.Solids additionentrains air intoinerted headspace, createsflammablemixture.Potential Solutionsand Control Mechanisms•Control rate of addition of solids, so as not toexceed inerting capacity•Charge solids by means of a closed system (e.g.,hopper and rotary airlock, screw feeder, double-dump valve system, etc.), with solids purgedwith inert gas prior to addition to vesselAGA XK0775CCPS G-23CCPS G-29FMEC 1997CCPS G-23CCPS G-29Fisher 1990ISA S84.0142.Vacuumtransfer•Install low level interlock on supply vessel tointoreactor,drumshut down transferorfeedtankruns•Monitor oxygen level in head spacedry,resultinginairbeingpulledintovessel,creatingflammableatmo-sphere.Potentialforfire/explosion.Also,potentialforstaticchargesgen-erationduetomistingofliquidatendoftransfer.43.Static charge gen-•Charge solids by means of a closed system (e.g.,eration due to toohopper and rotary airlock, screw feeder, double-rapid transfer outdump valve system, etc.)of drum or flexible•Control rate of solids addition (e.g., size ofintermediate bulkopening in super sack)container (super•Procedures and trainingsack).Inadequate venti-lation in ducts dueto partial obstruc-tions or closeddampers leadingto creation offlammable atmo-sphere and possi-bility offire/explosion.•Design dampers so that system will handle theminimum safe ventilation rate at maximumdamper throttling•Provide damper mechanical position stop to pre-vent complete closure of damper•Eliminate flammables or combustibles•Provide inert atmosphere•Design ventilation system to keep flammableconcentration below lower flammable limit•Install on-line flammable gas detection systemthat activates an inerting system•Provide automatic sprinkler protection•Use deflagration vents•Design for automatic isolation of associatedequipment via quick closing valves•Designsystemtocontainoverpressureifpractical•Install prescrubbers/condensers to reduce load inductCCPS G-22CCPS G-23CCPS G-29CCPS G-3244.ACGIH 1986API 2028Bossart 1974CCPS G-12CCPS G-23CCPS G-29CCPS G-41ISA S84.01NFPA 11NFPA 13NFPA 15NFPA 68NFPA 6988Potential Solutionsand Control Mechanisms4.EQUIPMENTNo.Concern/IssueOperator Exposure45.Palletizing/movingdrums incor-rectly-drum fallsand breaks oropens.AdditionalResources•Follow safe procedures for drum stacking andmoving•Use lockout/tagout proceduresCCPS G-3CCPS G-22CCPS G-29CCPS G-3246.Material released•Blow (purge) system, clean lines, before breakingAGAXK0775when transfer linesthe connectionCCPS G-22are disconnected.•Minimize use of hosesCCPS G-29FMEC 1997Lines are notdepressurizedbeforedisconnecting.•Follow proper operating instructions•Install or use small bleed valvesCCPS G-22CCPS G-23CCPS G-29CCPS G-22CCPS G-2947.48.Nitrogen pressur-•Check line integrity and all fittings, couplings,ization of lines oretc. before transfer is startedequipment that arenot sealed tight.Pressurization due•Stop transfer and de-pressurize before breakingto plugged transferline and clearing pluglines.Sampling spills.•Wear proper personal protective equipment(PPE)•Follow proper sampling procedures•Use safe sampling design49.CCPS G-22CCPS G-29CCPS G-22CCPS G-23CCPS G-29Lovelace 1979CCPS G-22CCPS G-23CCPS G-2950.51.Blowing downlines for cleaning.•Verify flow path before starting the flow.•Blow (purge) lines to safe location which pro-tects the operator and environment•Wear proper personal protective equipment(PPE)•Follow proper sampling procedures•Use safe blow-down designTable 4.6:Transferring and Charging Equipment89AdditionalResourcesNo.Concern/IssueOperator Exposure52.Vapor escapingfrom openmanway, engulfsoperator, couldignite resulting inflash fire.Runaway reactionwith manwayopen—foam out(can be acidbased), operatorcontacted by pro-cess materials.Potential Solutionsand Control Mechanisms•Provide local ventilation at charge hatch•Charge solids materials by means of a closedsystem (e.g., hopper and rotary airlock, screwfeeder, double-dump valve system, etc.), con-nected to vent system•Interlock manway with vessel pressure•Design system for closed manual operationACGIH 1986CCPS G-22CCPS G-23CCPS G-29CCPS G-22CCPS G-23CCPS G-29Fisher 1990ISA S84.0153.54.Operator exposure•Charge liquids and solids materials by means of aACGIH 1986to fumes or inerts.closed system (e.g., hard piping, hopper andCCPS G-22rotary airlock, screw feeder, double-dump valveCCPS G-23system, etc.)CCPS G-29•Provide local ventilation•Use proper personnel protective equipment(PPE)55.Operator comesinto contact withagitator throughmanway.•Implement procedures and training•Interlock manway with agitator rotation•Install scalping screen on manwayCCPS G-22CCPS G-23CCPS G-29Fisher 1990ISA S84.01CCPS G-23CCPS G-2956.•Provide mechanical assists for handling andErgonomic issuesduring charging,dumping of containershandling of heavyand unwieldy con-tainers, potentialfor personnelinjury.904.EQUIPMENTTable 4.7: Drumming EquipmentNo.Concern/IssueOverpressure1.Contaminants/foreign materialin drum, leadingto reaction indrum.Nitrogen blowthrough intodrum from feedvessel duringpressure transferleading to lossof containment.•Inspect drum before fillingCCPS G-3CCPS G-15CCPS G-29CCPS G-30•Provide level indicator in feed vessel withalarm/interlockAGA XK0775CCPS G-3CCPS G-15CCPS G-22CCPS G-23CCPS G-29FMEC 19973.Use of pumps totransfer materialto drum leadingto overpressure.•Limit filling rate to not exceed vent rate•Use metering pumpsACGIH 1986CCPS G-3CCPS G-15CCPS G-22CCPS G-23CCPS G-294.Vent bung capnot removedprior to filling.•Vent around feed nozzle through 2″bungopening•Select container designed to fail at low pressure•Follow proper drum filling procedure/checklistACGIH 1986CCPS G-3CCPS G-22CCPS G-23CCPS G-295.Vent systeminoperableor clogged.•Test system back pressure before use•Flow indication or pressure drop indicationACGIH 1986CCPS G-3CCPS G-22CCPS G-23CCPS G-29Overpressure6.Vent systemnot balancedwith inlet, orundersized.•Reduce feed rate or redesign vent systemACGIH 1986CCPS G-22CCPS G-23CCPS G-29Potential Solutionsand Control MechanismsAdditionalResources2.Table 4.7: Drumming Equipment91AdditionalResourcesNo.Concern/IssueOverpressure7.Overpressure ofmaterial in drumdue to externalheat input or selfheating.Potential Solutionsand Control Mechanisms•Store drum at proper temperature•Keep drum away from heat source•Ensure reaction is complete before drumming•Allow adequate freeboard for material•Provide adequate sprinkler protection•Thermally initiated venting (e.g., melt-out bungs)CCPS G-3CCPS G-15CCPS G-22CCPS G-29Loss of Containment8.Thermal expan-sion due to liquidoverfill leading toloss ofcontainment.•Drum at proper temperature•Keep drum away from heat source•Ensure reaction is complete before drumming•Allow adequate freeboard for each materialCCPS G-3CCPS G-14CCPS G-22CCPS G-29CCPS G-3CCPS G-14CCPS G-22CCPS G-29CCPS G-3CCPS G-15CCPS G-22CCPS G-29CCPS G-3CCPS G-22CCPS G-2912.Overfill drum due•Calibrate weighing devices and maintain equip-to operator errorment in good working orderor valve failure,•Use metering pumpscan lead to opera-tor exposure, slip-•Interock fill operation with weighing devicepery floors, spreadof flammableliquids.Material escapeswhen filters arechanged.•Blow (purge) system, clean lines before changingfilters•Isolate and drain filtersCCPS G-3CCPS G-15CCPS G-22CCPS G-299.Palletizing/moving•Follow proper palletizing and drummingdrums incor-proceduresrectly—drum•Stretch wrapping/strapping palletsfalls and breaks oropens.Drum not sealedproperly.•Seal containers as directed in operatingprocedures•Use new gaskets•Provide correct tools for sealing drums10.11.Drum not intact—•Inspect drum before useholes, cracks, etc.•Pressure check drums for leaks13.AGA XK0775CCPS G-3CCPS G-14CCPS G-22CCPS G-29FMEC 199792Potential Solutionsand Control Mechanisms4.EQUIPMENTNo.Concern/IssueAdditionalResourcesLoss of Containment14.Leaks in varioussystem compo-nents, hoses,valves, swiveljoints in arm,lance, etc.Lines are notdepressurizedbefore checking,changing filters.•Periodic replacement of components•Pressure test all lines•Ensure proper materials of constructionCCPS G-3CCPS G-22CCPS G-2915.•Follow operating procedures•Install pressure indication instrumentation andvent valvesCCPS G-3CCPS G-22CCPS G-23CCPS G-29CCPS G-3CCPS G-22CCPS G-2916.In solid drumming•Check liner position and integrity before fillingsystems, failure ofliner allowingpowder to blowout of thecontainer.Underpressure17.Thermal contrac-•Drumming at proper temperaturestion vacuum cre-•High integrity wallsated which cansuck air, moisture,•Store to prevent water accumulation on drumtopsetc., into drumcreating unwantedreaction; or col-lapse of the drum.CorrosionCCPS G-3CCPS G-15CCPS G-22CCPS G-2918.Drum not sealedproperly allowingreaction withmoisture, air, etc.Unsuitablematerials ofconstruction.•Follow proper sealing instructionsCCPS G-3CCPS G-15CCPS G-22CCPS G-2919.•Follow proper drum selection guidelinesCCPS G-1CCPS G-22CCPS G-23CCPS G-29Table 4.7: Drumming Equipment93AdditionalResourcesNo.Concern/IssueCorrosion20.Transfer systemcontaminated,(i.e., piping,pumps, filters,etc.)Externalcorrosion.Potential Solutionsand Control Mechanisms•Clean system on service changesCCPS G-3CCPS G-22CCPS G-2921.•Inspect drums before useCCPS G-3CCPS G-22CCPS G-2922.Contaminants/foreign materialin drum.Runaway Reaction•Inspect drum before useCCPS G-3CCPS G-22CCPS G-2923.Unsuitablematerials ofconstruction.•Select drum made of suitable material ofconstructionCCPS G-3CCPS G-22CCPS G-23CCPS G-2924.Drum not sealedproperly andforeign materialenters.Filters are dirtyand/or needchanging—incompatiblechemicals, etc.System notcleaned properly.•Seal drum per operating procedures•Use drum coversCCPS G-3CCPS G-15CCPS G-22CCPS G-2925.•Increase frequency of filter changes during ser-vice changesCCPS G-22CCPS G-29CCPS G-3026.•Increase frequency of cleaning•Clean system during service change•Visually inspect systemCCPS G-3CCPS G-15CCPS G-22CCPS G-29CCPS G-15CCPS G-22CCPS G-29CCPS G-3027.Reaction notcomplete beforetransfer/drumming.•Verify final batch analysis and conditions beforedrumming94Potential Solutionsand Control Mechanisms4.EQUIPMENTNo.Concern/IssueIgnition Sources28.AdditionalResourcesIncorrect electrical•Check area electrical classificationclassification forequipment orauxiliary equip-ment, lighting, etc.Ignition fromstatic charges;nongroundeddrums (i.e., fiber,plastic liners).•See that workers are equipped with static resis-tant clothing•See that workers use nonsparking tools•Use subsurface feeds for organic liquids•Ground and bond equipment•Use of conductive or static dissipative drums anddrum liners whenever possibleHigh TemperatureNFPA 7029.API RP 2003CCPS G-13CCPS G-22CCPS G-29CCPS G-32NFPA 77Pratt 199730.Drumming atincorrect tempera-ture. Possibility offlammable atmo-sphere, or initia-tion of thermallyunstable materials.•Follow operating procedures•Cool adequately before drumming•Don’t seal drums until material has cooled downsufficiently•Provide adequate fixed fire protection•Insure good ventilation•Check heat tracing for excessive heat input•Verify proper temperatures before drumming.•Use volumetric measurementACGIH 1986Bossart 1974CCPS G-15CCPS G-22CCPS G-29CCPS G-30CCPS G-15CCPS G-22CCPS G-2931.Density is lowerand drum may beoverfilled due tohigh materialtemperatures.Contact withoperator due tospill, over flow,hot drum, etc.Fire/Explosions32.•Drum at temperatures low enough to protectoperator against thermal injuryCCPS G-15CCPS G-22CCPS G-2933.Air, water drawninto drum.•Seal drums properly•Drum at correct temperaturesCCPS G-15CCPS G-22CCPS G-29Table 4.7: Drumming Equipment95AdditionalResourcesNo.Concern/IssueFire/Explosions34.Elevated drumtemperaturesreaching SelfAcceleratingDecompositionTemperature(SADT).Vapors in ventcollection systemin flammablerange.Potential Solutionsand Control Mechanisms•Evaluate thermal stability parameters of material(isothermal aging tests, SADT, etc.)•Keep drums away from source of heat•Drum and store at required temperatureCCPS G-15CCPS G-22CCPS G-29CCPS G-3035.•Monitor flammable concentration•Monitor oxygenconcentration•Install flame/detonation arresters•Design to be outside the flammable region in thevent system (N2purge, dilution air, etc.)ACGIH1986AGA XK0775API 2028Bossart 1974CCPS G-23CCPS G-29CCPS G-30FMEC 1987NFPA 69Low Temperature36.Material solidifiesor is too viscousand plugs lines.Potential forexposure whilecorrectingproblem.Operator Exposure37.•Design operation to minimize/eliminate dusts orDusts from solidfilling, vaporsvaporsfrom liquid filling.•Use proper personal protective equipment•Ensure proper design of local ventilationACGIH 1986CCPS G-3CCPS G-22CCPS G-23CCPS G-29•Monitor and control temperature in feed system•Heat trace and/or insulate lines•Use proper line break procedures•Use personal protective equipment (PPE)•Use proper lockout-tagout and confined spaceentry proceduresCCPS G-23CCPS G-29Fisher 1990964.EQUIPMENTTable 4.8: Milling EquipmentNo.Concern/IssueOverpressure1.Pressure build-up•Provide adequate venting and dust filtration ondownstream ofreceiving vessel ventmill (risk of com-•Where liquefied gas (nitrogen or CO) is used2ponent failure,for milling, ensure adequate vent sizing and limitparticularly in gasliquefied gas feed-rate to millconveying sys-tems). Internalpressure may alsoforce product outof the mill.Underpressure2.Failure of compo-•Ensure all system components, including flexiblenents inconnectors are rated for maximum feasiblesubatmosphericvacuum conditionspressure convey-•Ensure adequate pressure control system anding operations.back-up (e.g., vacuum relief devices)API 2000CCPS G-3CCPS G-11CCPS G-22CCPS G-29CCPS G-39High Temperature3.Overfeedingresulting in plug-ging of mill andsubsequent heatbuildup.•Limit feed-rate, design for uniform feed-rate (e.g.,CCPS G-12screw feeder or rotary valve)CCPS G-23•Measure temperature at strategic points in millCCPS G-29casing to detect and alarm product temperatureNFPA 654riseCCPS G-12CCPS G-23CCPS G-29CCPS G-11CCPS G-22CCPS G-23CCPS G-29Potential Solutionsand Control MechanismsAdditionalResources4.•Replace screen with one correctly sized and/orHeat build-updue to too fine orclean screenblocked outlet•Install pressure indicator downstream andscreen.upstream of mill for conveyed systems•Measure temperature at strategic points in millcasing to detect and alarm product temperaturerise5.Heat build-updue to worn oroverloadedbearings.•Ensure frequent preventive maintenance checkson bearings•Monitor and alarm bearing temperature•Ensure proper belt tensionCCPS G-12CCPS G-23CCPS G-29Table 4.8: Milling Equipment97AdditionalResourcesNo.Concern/IssueHigh Temperature6.Heat build updue to pluggeddischarge line.Potential Solutionsand Control Mechanisms•Design discharge to avoid bridging, provide reli-able instrumentation to detect full receiver (loadcells or level probe)•Checklinestoensuretheyareclearbeforestartup•Monitor and alarm temperatureCCPS G-12CCPS G-23CCPS G-29CCPS G-39CCPS G-12CCPS G-23CCPS G-29CCPS G-12CCPS G-23CCPS G-29CCPS G-1CCPS G-23CCPS G-297.Heat build-updue to loss ofcooling.Heat build-updue to mill run-ning too fast.Nonuniformfeedstock causesvariation in oper-ating conditionsresulting inoverheating.Low Temperature•Monitor and alarm temperature•Use coolant flow/temperature sensors or producttemperature sensors.•Use shaft speed sensor•Implement administrative controls on adjustablespeed drives•Feedstock should be blended before milling•Test feedstock before commencing milling opera-tion (e.g., moisture content)8.9.10.Component fail-ure when cryo-genic cooling isused.•Ensure all materials of construction exposed tolow temperatures are suitable (carbon steel, plas-tics, elastomers in seals, lubricants, etc.)•Provide adequate control system to maintaindesign temperatureCCPS G-29CCPS G-12CCPS G-23CCPS G-39Fisher 1990NFPA 55Runaway Reaction11.•Screen for thermal hazards prior to millingProduct in millexceeds tempera-materialture at which•Consider slurry milling prior to product isolationthermal runawayis initiated, result-•Measure temperature in mill casing and productoutlet to monitor for hot spots and interlock toing in explosion.shut system down and if appropriate initiate(This conditionquenching operationcan also occur in•Provide cooling jackets on mill or use cryogenicmill feedingcooling with liquefied gas such as nitrogen orequipment suchcarbon dioxideas screw feeders;similar counter-measures areappropriate.)CCPS G-1CCPS G-12CCPS G-27CCPS G-29Fisher 1990ISA S84.01Liptak 198298Potential Solutionsand Control Mechanisms4.EQUIPMENTNo.Concern/IssueCorrosion12.AdditionalResourcesInternal corrosion•Use appropriate materials of constructionin mill can occur•Maintain dry or inert atmosphere in mill at allif feed is high intimescorrosives, suchas halogens, andis hygroscopic.Ignition SourcesCCPS G-1CCPS G-23CCPS G-39Perry 198413.Hot bearings pro-•Avoid by regular preventive maintenance (PM)viding a source ofinspections, lubrication and belt checksignition.•Use improved lubricationTramp metalreaching millresulting in fric-tional heat-ing/mechanicalspark which pro-vides an ignitionsource.Static electricitygeneration bothin mill and con-veyingequipment.CCPS G-23CCPS G-29CCPS G-3414.•Provide suitable protection (e.g., magnetic separa-CCPS G-23tors, screens, etc.)CCPS G-29•Secure all potential sources of tramp metal (e.g.,CCPS G-34fasteners etc.) in upstream equipment•Use enclosed feed systems, not operator fedsystem•Inert milling system•Control/interlock with oxygen concentrationmonitoring•Ground, bond all electrically conductivecomponents•Use conductive materials of constructionCCPS G-12CCPS G-23CCPS G-29CCPS G-32ISA S84.01NFPA 65415.Fire/Explosion16.Leakage frommill ignited byspark or hotsurface.•Use adequate shaft sealing (mechanical or multi-ple gas purged lip or chevron seals). Hardenshafts in seal area•Use pressure tight flexible connections andclamps on mill inlets and outlets•Provide adequate fixed fire protection whereappropriateCCPS G-23CCPS G-29NFPA 13NFPA 15NFPA 16Table 4.8: Milling Equipment99AdditionalResourcesNo.Concern/IssueOperator Exposure17.Potential Solutionsand Control MechanismsOperator expo-•Use closed equipment wherever possible (hopperssure to hazardousand intermediate bulk containers (IBCs)).materials or•Where product is exposed at transitions or pack-broken mill partsing operations: use containment devices such asduring feedinggloveboxes; provide airflow control (laminar flowand packagingbooths); or as a last resort use the room as con-operations..tainment and provide suitable personal protectiveequipment for the operators•Provide local ventilation•Design charging chute to eliminate “line-of-sight”from mill to operator to reduce the possibility ofa broken mill part flying out of the chargingchute and causing injury.•Provide scalping screensManagement of ChangeACGIH 1986CCPS G-3CCPS G-22CCPS G-23CCPS G-2918.Running different•Develop procedures to characterize feedstockCCPS Y-28products throughwhenever changes have been made and reevaluatemill, or change inmilling conditionsupstream process,•Implement management of change reviewresulting in differ-procedureent feed charac-•Use adequate cleaning proceduresteristics andunsuitable millingconditions, e.g.overheating dueto blocked outletscreen.General19.Thermal decom-position of mate-rial duringmilling.•Perform thermal and shock hazards analysis priorto milling•Consider milling under different conditions, e.g.,slurry milling•Use liquid nitrogen injection as a coolantCCPS G-1CCPS G-23CCPS G-27CCPS G-29CCPS G-41CCPS G-23CCPS G-2920.Tramp metalfrom mill causesdownstreamproblems.•Provide screens or magnetic separator on milloutlet1004.EQUIPMENTTable 4.9:FiltersPotential Solutionsand Control MechanismsAdditionalResourcesNo.Concern/IssueOverpressure1.Ignition of com-bustible or flam-mable materialwith filter closedor filter box lidclosed.•For closed filters, purge filter with inert gas•For open filters, use alternate closed filteringmethods such as plate and frame•Add antistatic agent to nonconducting solvents•Bond and ground the piping and equipment•Provide appropriate area electrical classification•Heat activated device triggers CO2or inert gasblanket•Loss of filter box ventilation shuts off solventfeed•For filter boxes, use drop tube with dam forsubsurface addition to minimize static generation•For filter boxes, provide internal filter boxventilationAGAXK0775ARI RP 500API RP 2003CCPS G-22CCPS G-23CCPS G-29FMEC 7-59NEC 70NFPA 77NFPA 497Pratt 1997High Temperature2.Feed slurry tem-•Use alternate closed filtering methodsperature is high,•Check and adjust source temperature prior toresulting in exces-transfersive flammable•Design filter box ventilation for excessive flam-vapors for openmable vaporsfilters.Friction fromcontact of movingparts, trampmetal, bearings orseals initiatingthermal decom-position or ignit-ing flammablevapors.•Maintain proper clearances•Screen chemicals to be filtered for thermalstability•Evaluate and design for pressure consequences ofthermal decomposition•Evaluate potential for solid phase deflagration•Eliminate tramp metal and broken parts that maycause localized overheatingCCPS G-1CCPS G-23CCPS G-27CCPS Y-28CCPS G-1CCPS G-23CCPS G-27CCPS G-39CCPS G-413.Table 4.9:Filters101Potential Solutionsand Control MechanismsAdditionalResourcesNo.Concern/IssueRunaway Reaction4Unwanted reac-tion due to con-taminants inequipment or sol-vent wash.•Clean and inspect equipment after each change•Segregate incompatible materials•Label material, lines, pumps and valves•Use double check system•Check labels against batch sheets•Use procedures and training•Set valves to correct flow pathAPI 750ASTM Pro-posal 168CCPS G-15CCPS G-22CCPS G-27CCPS G-29CCPS G-32Frurip 1997Sutton 1995Fire/Explosion5.Improper cloth or•Include proper handling and disposal in operatingfilter media dis-proceduresposal may result•Use high temperature filter mediain fire and explo-•Use flame retardant personnel protectivesion hazard.equipment•Inert/purge filter with nitrogen6.Spontaneouscombustion ofpyrophoric mate-rial in the filterafter opening orblowing dry.For open filters,or when openingclosed filters, sol-vent is flammableand may be aboveflash point withair present. Foropen filters, ventsystem failuremay increase sol-vent vapor con-centration,resulting in a fireor explosion.•Rinse filter with water (or other appropriate sol-vent) prior to opening•Upon opening, immediately transfer cake to safeshipping container while still wetAGA- XK0775CCPS G-22CCPS G-23CCPS G-29CCPS G-31FMEC 1997AGA- XK0775CCPS G-297.•Rinse filter and cake with cool solvent prior toopening filter•For closed filters, purge filter with nitrogen priorto opening, cleaning or starting solvent slurry•Use nonflammable solvent where ever possible•Use alternate closed filtering methods•Design internal filter ventilation for excessiveflammable vapors•Provide adequate building ventilation•Install local air exhaust pickup points at filter(e.g., elephant trunks)(Continued on next page)ACGIH 1986AGA- XK0775Bossart 1974CCPS G-22CCPS G-23CCPS G-29CCPS G-31ISA RP 12.13(Continued)102Potential Solutionsand Control Mechanisms4.EQUIPMENTNo.Concern/IssueFire/Explosion7.(Continued)AdditionalResources•Provide combustible gas analyzers•Provide automatic area sprinkler/delugeprotection•For filter boxes, interlock filter box ventilationwith solvent feed•For filter boxes, keep closed whenever possibleand keep solvent in bottom pumped out•For filter boxes, provide remote and automaticfilter box lid closing on trip of appropriate firedetection device. Fire detection device may alsobe interlocked to stop solvent feed, trip delugeinternal to filter box and/or trip inert gas blanketfor filter box (caution, be aware inert gas is apotential asphyxiation hazard)•For filter boxes, use flexible, conductive plasticfilm on surface of cake to minimize fumes•Use flame retardant personnel protectiveequipmentNFPA 13NFPA 15NFPA 16NFPA 30Ignition Sources8.Ignition of flam-mable atmo-sphere for openfilters or solventmay be aboveflash point withair present whencleaning orunplugging closedfilters. This maynecessitate tightcontrol of igni-tion sources toprevent afire/explosion.•Cool and/or rinse filter prior to opening filter•Check area electrical classification•Control humidity of air in operating area toreduce accumulation of static electricity•Use conductive floors•Ground the operator with proper clothing (con-ductive shoes, gloves, etc.)•Periodic testing of conductive shoes•Implement procedure for manual bonding andgrounding of tools to filter box•Avoid use of nonconductive materials ofconstruction•Use nonsparking tools•Perform conductivity tests on slurry before feedto filter•Use antistatic agent with nonpolar solvents•On filter boxes, use drop tube with dam forsubsurface addition to minimize static generation•Control velocity/turbulence of solvent addition•Provide adequate fixed fire protection whererequiredAPI RP 2003API RP 500CCPS G-22CCPS G-23CCPS G-29CCPS G-31CCPS G-32CCPS G-41NFPA 498NFPA 70NFPA 77Pratt 1997Table 4.9:Filters103Potential Solutionsand Control MechanismsAdditionalResourcesNo.Concern/IssueLoss of Containment9.Overfill by plug-ging, blindingcloth, failure tostart underflowpump, loss ofvacuum or byoperator error.•Use alternate filtering methods•Provide combustible gas analyzers•Provide high level cut-off interlocked with sol-vent feed•Provide level control system on filtrate receiverswith bottoms pumps•For vacuum transfer of filtrate, alarm on loss ofvacuum•Provide overflow line from filter to drain•Provide area diking and containment•For filter boxes, provide overflow line to safelocation•Provide pressure drop monitor for closed filters10.Leakage of flam-mable or toxicchemical fromequipment.•Provide vapor-tight enclosure around filter andrun at negative pressure with exhaust fans•Implement frequent maintenance of sealing sur-faces and clamping systems•Use new gaskets where appropriate•To protect clamping system, use dissimilar metalsto prevent galling on threaded fasteners•Check area electrical classification•Provide emergency ventilation11.Leakage of flam-mable or toxicchemical fromrotary vacuumfilter.•Provide vapor-tight enclosure with adequatelighted viewing window around filter and run atnegative pressure with exhaust fans•Route solid discharge directly into receiver tank•Provide catchment trough and routine mainte-nance to minimize valveplate leakage•Provide overflow/high level shutoff on feedtrough•Check area electrical classification•Provide emergency ventilation•Provide adequate fixed fire protection whereappropriateAPI RP 500CCPS G-22CCPS G-23CCPS G-29CCPS G-31CCPS G-39Lees 1996NFPA 497API RP 500CCPS G-22CCPS G-23CCPS G-29CCPS G-31CCPS G-39Lees 1996NFPA 497CCPS G-15CCPS G-22CCPS G-23CCPS G-29CCPS G-31ISA RP 12.13Lees 1996104Potential Solutionsand Control Mechanisms4.EQUIPMENTNo.Concern/IssueOperator Exposure12.Incomplete con-version of mate-rial orcontaminatedmaterial couldlead to operatorexposure.AdditionalResources•Test material prior to filtering•Use appropriate personnel protective equipment•Design filter box ventilation for excessive flam-mable vapors•Segregate incompatible materials•Clean and inspect equipment after each batch•Use procedures and trainingACGIH 1986CCPS G-3CCPS G-1CCPS G-22CCPS G-23CCPS G-29CCPS G-31Gibson 1991Lees 1996Lovelace 1979NFPA 49813Operator expo-sure to toxicvapors duringopening andcleaning.•Purge prior to opening or cleaning•Use appropriate personnel protective equipment•Use alternate closed filtering methods•Use cleaning methods which don’t require open-ing the filters•Provide adequate building ventilation•Provide local air exhaust pickup points at filter(e.g. elephant trunks)ACGIH 1986AGA- XK0775CCPS G-3CCPS G-15CCPS G-22CCPS G-23CCPS G-29CCPS G-31NFPA 199314Improper dis-posal of filtermedia may resultin operatorexposure.•Include proper handling and disposal in operatingCCPS G-15proceduresCCPS G-22•Use appropriate personnel protective equipmentCCPS G-29•Provide local air exhaust pickup points at filterCCPS G-31CCPS G-32CCPS Y-2815.Ergonomic issues•Use alternate filtering methodsin manual wash-•Provide ergonomic design, mechanical assisting, unloading,setup, cleaning,shoveling of filterboxes, moving ofportable units e.g.plate and framefilter press.CCPS G-15Sanders 1993Appendix 4A. Storage and Warehousing105AdditionalResourcesNo.Concern/IssueOperator Exposure16.Potential Solutionsand Control MechanismsManual operation•Use alternate filtering methodsplaces operator in•Use appropriate personnel protective equipmentclose proximityto potentialhazards.Brandt 1992CCPS G-15CCPS G-22CCPS G-31Mecklenburgh1985NFPA 1993Appendix 4A. Storage and WarehousingStorageareasintheplantusuallycontainthelargestvolumesofhazardousmate-rials.Frequentlystorageareascontainflammableliquidsorliquefiedgases.Themainconcerninthedesignofstorageinstallationsforsuchliquidsistoreducethehazardoffirebyreducingtheamountofspillage,controllingthespill,andcontrolling the ignition sources.Itcannotbeemphasizedenoughthatreducingthequantitiesofhazardousmaterialsisthesinglegreatestmethodforreducingthehazardsoffireorexplo-sion.Minimizingstoragequantitiesalsoreducesthepotentialforlargespillsandfurtherdamage.Pipelinefeedsfromareliablesourcecaneliminatetherequire-ment for large storage areas.Solidchemicalsmaybestoredinbulkinbins,hoppers,pilesorcontainers.Liquidchemicalsmaybestoredintanks,reservoirsorspecifiedshippingcon-tainers.Gasesmaybestoredinlow-pressuregasholders,inhighpressuretanksorcylinders;orinliquidformintanksorcontainersunderpressure,refrigera-tionorboth.Pressureandtemperatureofstoragegreatlyaffectsdispersion/emissionofliquidorvaporincasecontainmentislost.Importantconsiderationsare separation distances and diking arrangements.Theprimaryadditionalsafetyconcernwhenhazardousmaterialsarestoredincontainersisthelargeamountofvehicleandemployeetrafficassociatedwiththeuseofcontainerscombinedwiththehazardcausedbyconstanthandling.Storageareasshouldbedesignedtoallowthesmoothflowoftrafficwithouttheneedtoconstantlymaneuveraforkliftortruck.Thestorageareashouldbearrangedtoallowpersonnelaccesstoinspectallcontainersforleakageorotherdamageonaregularbasis.Thestorageofcompressedgasesandflammableandcombustibleliquidsshouldmeettherequirementsandapplicableguidancecon-tainedinindustryconsensusstandardsandregulations.Incompatiblematerials106
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shouldbekeptseparatedsothatanyspillscannotmix.Thestorageofcontainersinrackareasmayrequirespecializedfirecontrolsystemssuchasindividualsprinklerlinestodeliverwaterorfoamdirectlytoeachracklevel.Theplace-mentofdrumsinprocessingareaforthedispensingofthecontentsmaynotneedtomeetthesamestringentstoragespecifications,butitwillstillbeneces-sarytomeetallpertinentsafetyrequirements.Theprocessdrumsareamayincludesafetybarrierstopreventtrafficfromhittingthedrums,portabledrumsumpstocontainanyspills,aventilationsystemtocontrolfumes,anddoublevalving or a valve and plug to minimize drum leakage.
Duringbatchoperationsmostmaterialswillrequireoneorseveralstepsofwarehousingorotherstorageoutsideoftanksorvessels.Thistypeofgoodsstoragecanoccurinwarehousesorbuildings(roofandwalls),openair,underaroof(nowalls),inatentorinflatableenclosureorsimplyinthestagingarea.Largewarehousestorageofhazardousmaterialsinparticularmaypresentadangertopeople,theenvironmentorplantoperations.WarehousefiresatSandoz(Basel,1986)andinNorthAmericahaveresultedinstrictrequirementsinmostEuropeanjurisdictionsandareappraisalofNorth-Americanrequire-ments.Fireandfire-fightingconsequencesthatrelatetothestorageoflargeamountsofhazardousmaterialsasincertainwarehouses,needtobeevaluatedtodetermineiffire-fightingisappropriate.Environmentalandfirefightersafetyneedtobetakenintoconsiderationandsometimesthedecisioncouldbetoletafire burn itself out.
Storageandreceivingareactivitiesthatcangreatlycontributetoasafeandeconomicoperation.Itisherethatqualitycontrolcanbeachievedatminimalcost.Labelverificationandotherqualityassurancemeasurescanincreasetheconfidencelevelthatthecorrectchemicalshavearrived,therebypotentiallycir-cumventingtheuseofwrongchemicals.Wronglyshippedchemicalscanbereturnedtothemanufacturerwithminimalornocosttothebatchoperationowner.Aswithallprocessesandactivitiesitisofgreatimportancetoapplytheprinciplesofinherentsafety,inparticulartheminimizationandattenuationprinciples (CCPS G- 41).
Materialsthatcanreactwitheachothershouldbestoredinsegregatedareas.Specialattentionisneededforcorrosivematerialswhichuponleakagefromtheirprimarycontainment(e.g.,aplasticbag)cancorrodetheirmaincon-taineraswellasothercontainersholdingdifferentchemicalsinadjacentareas.Propermaterialhandlingproceduresneedtobedevelopedandfollowedandcorrecttoolsshouldbeused.Forexample,theuseofforklifttruckswithroundedforkstoavoidpuncturingdrums/bagscouldbeconsidered.Hazardsassociatedwithstackedpalletsloadedwithshrink-wrappedbagsoffreeflowingmaterialsthatcantoppleoverwhenbagshavebeenpuncturedshouldberecog-nised.Storageareasshouldbeinspectedonaregularbasisanddamagedbags,
Appendix 4A. Storage and Warehousing
107
drumsandothertypeofcontainersshouldbeisolatedandproperlydiscardedbystaff using appropriate personnel protective equipment (PPE).
Example:AwarehouseintheUKstoredlargenumbersofmetaldrumsholdingbaggedpesticides.Inordertospottornbags,quicklyandeasily,holeshadbeendrilledinthebottomofthemetaldrums.Whilethishelpedthehouse-keepingeffortsitnegatedthecontainmentfunctionofthedrums.Thebagsmeltedduringafireandthepesticideendedupinthefirewater,creatingacon-siderable environmental problem.
Reactivechemicalsareoftenstoredunderaninertmaterialoratmosphere,storedinadilutedform,orstabilizedbyachemicaladditive.Thesesituationsrequire special care; for example:
•Vaporizationofsolventscoveringalkalimetalsduringstoragecanexposethe metals to moisture.
•Vaporizationofdilutingsolventsmayincreasetheconcentrationofreac-tive chemicals to unsafe levels.
•Lowtemperaturescancauseaphaseseparationinstabilizedsolutionsinwhichcaseonephasecanbecomedeficientinstabilizerandsubjecttorunawayreactions.Acrylicacidcancrystallizeoutofstabilizedsolution,andsubsequentthawingoftheseessentiallypureacrylicacidcrystalscaninitiaterunawayreactions,oftenwithsevereconsequences.Thawingofcrystallized(frozen)materialsneedstobeaccomplishedusingestablishedproceduresinthawboxesorsimilardevices.Ifestablishedproceduresarenotavailable,asafetyreviewneedstobeconductedandaproceduredeveloped prior to thawing the material.
•Heatsensitivematerialsneedtobestoredawayfromheatsourcessuchheaters and windows where they are subject to solar radiation.•Shelf life of stabilizers or inhibitors may be limited
•Somestabilizersorinhibitorsrequireacertainoxygenconcentrationinthetankheadspaceatmosphereinordertofunction.Whereinertingisrequired,carefulcontrolisnecessarytomaintainthisminimumoxygenconcentrationininertinggaswhilestillstayingbelowtheminimumoxygen concentration required for combustion.
•Phasechangesalsomeanthatpressureandorvacuumreliefneedstobeconsideredinordertomaintainthemechanicalintegrityofthecontainer.Correctstoragerequirements,procedures(e.g.,firstin,firstout)andcon-ditionssuchastemperaturecontrolissuesincludinginsulation,cooling,heatingand ventilation need to be determined and implemented.
Potentialignitionsourcesneedtobeeliminatedorprotectedagainstbyproperbonding,grounding,andlightningprotection(NFPA77,NFPA780,Pratt1997).Goodhousekeepingisanotheressentialingredientforthe
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preventionofmix-upsandunanticipatedadverseconsequences,e.g.,firecausedby smouldering dirty rags.
Anumberofcodes,standards,guidelines,andrecommendedpracticespro-mulgatedbyorganizationssuchasNFPAandAPIareprovidedinthereferencesection. Additional guidanceapplicable towarehousing includes
•AGuidetoSafeWarehousingfortheEuropeanChemicalIndustry,ConseilEuropeendesFederationsdel’IndustrieChimique,April15,1987.
•GeneralStorageSafeguards,LossPreventionDatasheet8-0,FactoryMutual Engineering Corp.
•WarehousingofChemicals,LossPreventionBulletin088,IChemE,August 1989.
•ProtectionofWarehousesAgainstFire,LossPreventionBulletin084,IChemE, 1989, pp. 2–6.
•TheForgottenHazards:ServicesinWarehouses,LossPreventionBulletin084, IChemE,1989, pp. 7–12.
•OpslagvanGevaarlijkeStoffen,ComiteEuropeendesAssurances,Sep-tember 1988.
•CCPSG-3.GuidelinesforSafeStorageandHandlingofHighToxicHazard Materials.American Institute of Chemical Engineers, New York•CCPSG-30.GuidelinesforStorageandHandlingofReactiveMaterials.American Institute of Chemical Engineers, New York.
•CCPSG-33.GuidelinesforSafeWarehousingofChemicals.AmericanInstitute of Chemical Engineers, New York.
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