Christmas Eve refinery explosion cause by frozen, ruptured pipe

8/10/2019 Christmas Eve refinery explosion cause by frozen, ruptured pipe

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EXECUTIVE REPORT

C O O P R E F I N E R Y C O M P L E X I N C I D E N T

D E C E M B E R 2 4 , 2 0 1 3


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TechnicalSafetyAuthorityofSaskatchewanExecuveReport

October2014

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TechnicalSafetyAuthorityofSaskatchewanEXECUT IVE REPORT

CO OP REF INERY COMPLEX INC IDENT DECEMBER 24 , 2013

INCIDENTSUMMARYOnDecember24,2013atapproximately3:25pmlocaltime,anexplosionoccurredinthePolymerization

Unit27(PMU)attheCoopRefineryComplex(CRC)inRegina,Saskatchewan. Theensuingfirewas

extinguishedatapproximately9:00pmlocaltimeonDecember24,2013. Theblastandfiredestroyedthe

equipmentandstructurearoundreactors1,2and3inthePMU. TheremainingfivereactorsinthePMU

sufferedblastandpostincidentfreezingdamage,andwererenderedunusable. Blastdamagealso

occurredtoCRCbuildingsandequipmentoutsideofthePMU. Blasteffectswerealsofeltatlocations

outsidetherefinerycomplex. Nopersonnelwereinjuredintheincidentorinthesubsequentemergency

response. Figure1showsapartialviewoftheexplosionfromaCRCsurveillancecamera. InFigure1,the

PMUisnotwithintheviewofthesurveillancecamera,butislocatedoutsidetheupperleftoftheimage.

Figure1: Explosionat3:25PMDecember24,2013


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REFINERYDESCRIPTION

LocatedinRegina,Saskatchewan,theCoopRefineryComplex(CRC)isawhollyownedsubsidiaryof

FederatedCooperavesLimited(FCL)whichownsandoperatestheCoopRefineryComplex(CRC)

facilies.

TheCRCwasincorporatedonApril1,1934,andonMay27,1935produconof500barrelsofcrudeoilper

daybegan.TheCRCcelebratedits79thyearofoperaonin2014.

CRCFactsandHighlights:

Occupies575acresoflandinNorthRegina;

Employsover800peopleonapermanentbasis;

Employsandcontractsover1,000addionalpeopleduringpeakmaintenanceperiodsand

turnarounds;

A$2.7billionprojecttoexpandandrevamptheCoopRefineryComplexwascompletedin2013;

TheexpandedCRCcurrentlyhasabalancedproductcapacityof130,000BPDandpotenalfor145,000BPD;

Approximately36.5millionbarrelsofcrudewereprocessedin2013,a20percentincreaseover

2012andthelargestvolumeprocessedinthehistoryoftheCRC.

INVESTIGATIVEPROCESS

TheinvesgaonbeganwithemergencyresponsebyReginaFireandProtecveServices(RFPS)ontheday

ofDecember24,2013.RFPSsecuredthesceneandbeganinialassessmentsandevidencecolleconon

December25,2013. TheTechnicalSafetyAuthorityofSaskatchewan(TSASK)iniateditsinialdata

colleconandassessmentonDecember24,2013.OnJanuary7,2014TSASKandRFPSformedajointinvesgaonteamcomprisedofmembersfrombothorganizaons.

PMUDESCRIPTION

ThepurposeofthePMUistotakelightolefinsresulngfromtheFluidCatalycCrackingUnit(FCCU)

processandpassthemoveraphosphoricacidcatalystinsidepolymerizaonreactorstoproduceahigher

molecularweightproductcalledpolygasoline. ThePMUreactorsoperateatapproximately1060psig

internalpressureat390F. ThePMUhadatotalofeightpolymerizaonreactorsandadisllaonsecon

forpropane,butane,andgasolineseparaon. The"frontend"oftheunitincludesanaminetreatment

seconandcauscandwaterwashestoremovecontaminantsfromthefeedstock. Figure2illustratesthe

PMUpriortotheincident. Theunitisdesignedto:

1. Collect"polyfeed",propane,butane,andolefinsforchargetothereactors;

2. Treat"polyfeed"forhydrogensulfide,mercaptan,andnitrogencompoundremoval;

3. Processolefinsoveracatalystbedtocreatepolygasoline;

4.

Distillandseparateoutpropane,butane,andpolygasolineproducts.


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OPERATIONSIMMEDIATELYPRECEDINGTHEEXPLOSION

Prior

to

the

incident

on

December

24,

2013,

the

PMU

was

opera

ng

within

normal

parameters

forfl

ows,

pressuresandtemperatures. Operatorsdidnotobserveanythingoutoftheordinaryduringprocess

operaonsthatday. ThefirstindicaonofaprobleminthePMU,asreportedbywitnesses,wasawhistling

noiseanumberofsecondspriortotheexplosion. Instrumentaonforpolyfeedflowtoreactors#1and#3

inthePMUrecordedbaddataqualitysignals16secondspriortotheappearanceoftheexplosionona

surveillancecamera. Thebaddataqualitysignalswerecausedbytheescapeofpolyfeedfromarupturein

thepipinginthePMU.

Figure2: PolymerizaonUnit27(PMU)Before


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INCIDENTANALYSIS

Preceding MaintenanceOutages

IntheweeksbeforetheDecember24,2013incident,thereweretwoPMUmaintenanceoutages,as

follows:

Outage1: ThePMUwasshutdownbetweenNovember26,2013andDecember4,2013duetoa

maintenanceoutageontheupstreamfluidcatalyccrackingunit(FCCU). Sincethisresultedin

shutdownofthepolyfeedfromtheFCCUtothePMU,opportunitywastakentoperform

maintenanceinthePMU. AnumberofmaintenanceitemsinthePMUwereidenfiedand

completed.

Outage2: ThePMUwasshutdownbetweenDecember12,2013andDecember18,2013dueto

anothermaintenanceoutageontheupstreamFCCU. Thisoutageagainresultedinshutdownof

feedfromtheFCCUtothePMU,althoughtherewasnomaintenanceperformedinthePMUduring

thisoutage.

Outage1: November 26, 2013 December 4, 2013

InordertopreparetheFCCUforthemaintenanceacviesduringoutage1,awaterfloangprocedure

wasusedtopurgehydrocarbonsfromtheFCCUpipingandvessels. Waterfloanghadhistoricallybeen

usedforthepurposeofpurginghydrocarbons. Waterfloangisaprocessthatulizeswatertoflush

hydrocarbonresiduefromthesystemandrenderthepipingandvesselsfreeofexplosivehydrocarbonsand

safeforwork. Theintentwasforthewaterfloangproceduretointroducewateruptothewaterbooton

thecombinedfeeddrum,whichislocatedupstreamofthePMUreactors. Itwasintendedthat

instrumentaonandasightglassonthewaterbootofthecombinedfeeddrumwouldbeusedtodetect

thewaterleveltoenabletheintroduconofwatertobeproperlystoppedatthatpoint. ThecombinedfeeddrumwaslocatedupstreamofthePMUreactors,andlimingthewateratthecombinedfeeddrum

waterbootwouldprecludeanywaterfromreachingthePMUreactors.

Duringoutage1,thewaterfloangprocedurewasiniatedduringthenightshi ofNovember26,2013,as

planned,buttheprocessfailedtostopthewateratthecombinedfeeddrumwaterboot. The

instrumentaonatthewaterbootwasdefecveandthesightglasswasdifficulttoread. Waterwas

pumpedpastthecombinedfeeddrumandintothePMUpipingandreactors. Thepumpingofwaterinto

thePMUpipingandreactorswasnotintended. Theshutdownguidelinesforbothoutagesspecifiedthat

thepolymerizaonreactorsweretobepurgedwithnitrogengasastheyweretakenoffline. Figure3

illustrates

the

planned

and

es

mated

actual

extent

of

waterfl

oa

ng,

as

well

as

a

schema

c

representa

on

ofapolyfeedbypassline.

MaintenancepersonnelbegandrainingwaterfromthePMUonNovember27,2013,however,issueswith

freezingwaterwereencounteredasthisprocesswasundertaken,especiallyastemperaturesdroppedat

night. Waterdrainingandicethawingacviesconnuedthroughtheremainderofoutage1. Thawing


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methodsincludedthewrappingofsteamtracelinesaroundprocesslines,aswellastheinseronofsteam

lancesintopipinginsulaonjackets.

Duringoutage1,outdoortemperaturesdroppedconsiderablytowardtheendoftheoutage,ascanbeseen

inthemelineandtemperaturedatashowninFigure4.

Figure3: WaterFloangExtent


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Nov. 26, 2013

Outage 1 begins.

Maintenance work

in FCCU and PMU

is performed

during this outage.

Water floatingprocedure done on

night of Nov. 26

accidentally

introduces water

into the PMU

including bypass

line 123BPL.

Dec. 5, 2013

Operations resume.Numerous frozen

lines in the PMU

require thawing.

Bypass line 123BPL

was found frozen

and was thought to

have been thawed.

Dec. 24, 2013

Operations are

within normal

parameters with

no indication of a

problem.

Rapidly rising

temperatures

cause the ice plug

in bypass line

123BPL to thaw

and allow high

pressure poly

feed to escape

from the rupture in

the bypass line.

The hydrocarbons

ignite causing an

explosion in the

PMU.

Dec. 19, 2013

Operations resume and are within normal

parameters during Dec. 19 23 with no

indication of a problem.

At some point, ice formation in bypass line

123BPL causes the bypass line to rupture.

An ice plug remains inside bypass line

123BPL, preventing the escape of poly

feedDec. 12, 2013

Outage 2 begins.

Maintenance done

to pressure relief

valve in FCCUresulting in feed

outage to the PMU.

Water floating not

done in this outage.

Dec. 23, 2013

The coldesttemperatures

during the period

Nov. 26 Dec. 24

are reached

during the early

morning hours of

Dec. 23.

Figure4: TimelineofEvents NovembertoDecember,2013


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Unit OperationDecember 5, 2013 December 11, 2013

AstheFCCUandPMUweregraduallybroughtbacktooperaonaeroutage1,manyfrozenprocesslines

connuedtobefoundandrequiredthawinginordertomakeprogress. ThePMUreactorinletsandoutlets

werefoundfrozen. Thereactorfeedbypassline123BPLwasalsofoundfrozen. Gradually,processlines

werethawedandunitoperaonwasachievedbyDecember6,2013.

Reactorfeedbypassline123BPL,locatedadjacenttoPMUreactor2,isapartofthePMUandservesto

divertfeedstockflowaroundPMUreactors1,2and3whenflowthroughthereactorsisnotneeded. Flow

throughreactorfeedbypassline123BPLwasnotnecessaryduringthestartupandoperaonofthePMU,

andthislineisnormallyclosedduringPMUoperaon. Bypassline123BPL,showninFigure5,formsa

naturaldeadlegwhentheblockvalveslocatedattheboomofthelineareclosed. Deadlegsare

componentsofapipingsystemthatnormallyhavenosignificantflow. Deadlegscanaccumulatewaterand

freezemorereadilythanpipingthatisopentoflow. Deadlegsfrequentlyrequiregreateraenonwhen

thawinganddraininginordertoachievecompleteclearing. Operatorswereunderthebeliefthattheyhad

thawedanddrainedbypassline123BPLduringtheireffortstoachieveunitoperaon. Thethawingand

drainingofthefrozenlineswasnotsystemacanddocumented,butreliedonoperatorexperseand

memory. Theinvesgaondeterminedthatbypassline123BPL,infact,wasnotproperlydrainedofwater.

DuringtheperiodofoperaonfromDecember5,2013toDecember11,2013temperatureswerecold

throughoutascanbeseeninthemelineandtemperaturedatashowninFigure4.

Outage2:December12 December18,2013

Thepurposeofoutage2wastorepairafailedpressurereliefvalveintheFCCU,againresulnginshutdown

ofthePMUduetoaninterruponoffeedfromtheFCCU. Duringthisoutage,procedureswererevisedin

ordertomigatethefreezingissuesexperiencedduringoutage1,andwaterfloangdidnotimpactthe

PMUreactorsandpiping. Addionally,nomaintenanceacvieswereperformedinthePMU. Theshutdownandsubsequentstartupaeroutage2wentrelavelysmoothly,withnoaddionalfreezing

issues.

Theinvesgaondeterminedthatthebypassline123BPLlikelyremainedfilledwithwaterthroughoutage

2.

Duringoutage2,temperatureswarmedupconsiderably,peakingat0ConDecember16,2013,andthen

droppeddramacallytoastaclowof24Cwithawindchilllowof34Cattheendofoutage2on

December18,2013,asshowninFigure1.


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Figure5: RupturedBypassLine123BPL


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UnitOperaonDecember19,2013December24,2013

TherewerenofreezingissuesthataffectedunitstartupandoperaonduringDecember19to24,2013.

ThePMUfunconedwithinnormalparametersforpressures,temperaturesandflowsduringthisperiod.

Operatorswerenotawareofanyprocessproblemsthatcouldleadtoacomponentfailureduringthis

period.

OutdoortemperatureswereverycoldfromDecember19,2013toDecember21,2013. Beginningon

December22andconnuingintoDecember23outdoortemperaturesdroppeddramacallytoastaclow

of35Cat2:00AMonDecember23andawindchilllowof47Cat6:00AMonDecember23. These

were,infact,thecoldesttemperaturessincethewaterfloangprocedureofNovember26,2013.

Thebypassline123BPLdeadlegcontainedwaterthroughoutthecoldweatherthatoccurredbetween

November26,2013andDecember24,2013. Waterinthelinefrozeandrupturedthelinedueto

hydrostacoverstressatsomepointduringthisperiod. Aniceplugexistedwithinthelineandcreateda

sealwhichpreventedtheescapeofhighlyvolalepolyfeedthroughthepiperupture.

Beginningat6:00AMonDecember23,2013thetemperaturebegantorisedramacally,peakingat2Cat

2:00PMonDecember24,2013.

OnDecember24,2013unitoperaonswerewithinnormalparameters. DuetotheChristmasholiday,a

numberofoperaonsstaff hadle earlythatday,resulnginmuchfewerthannormalpersonnelaround

thePMUasthedayprogressed.

Asoutdoortemperatureswarmed,combinedwithheatfromunitoperaons,theicepluginbypassline

123BPLthawedandeventuallygavewaytothehighpressurepolyfeed. At3:25PMthiscausedasudden

releaseofhydrocarbonsintothePMU,followedbyalargeexplosionandensuingfire. Theexplosionand

firewerecentredonPMUreactors2and3,resulnginextensivedamagetothePMUstructurearound

reactors1,2,3. TheexplosioncausedblastdamagetootherareasofthePMUaswellastosurrounding

buildingsinotherunits. TheblastwasfeltinareasofReginawelloutsidetherefinerycomplex.

Figure5showstherupturedbypassline123BPLaertheincident. Figure6showstheextentofdamageto

thePMU.


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Figure6: DamagetothePMU


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FINDINGSANDRECOMMENDATIONS

1. Proceduresforcoldweathershutdownshouldberevisedtoimprovedecisionmakingandthe

idenficaonofcondionswhencoldweathershutdownispermissibleandcondionswhenitis

not.

Proceduresforcoldweathershutdownwereinadequate,astheydidnotconsiderthehighrisksposedbyextremecold.

2. Proceduresforincidentinvesgaonshouldberevisedtoensurethatcorrecveaconsare

implementedsothatincidentsdonotrepeat.

AsimilarpiperuptureduetofreezingoccurredinDecember,2008,wheretheresulngvapour

clouddidnotignite. Effecvecorrecveaconswerenotimplemented.

3. CRCshouldestablishawrienfreezeproteconprogramthatincludestheidenficaon,

migaon,managementofchangeandauditrequirementsforequipmentatriskduetofreezing.

4. Proceduresforwaterfloangshouldberevisedtoensurethatinstrumentaonandprocess

controlsareeffecveandmaintained. Addionalredundancyininstrumentaon,controlsand

verificaonmethodsshouldbedeveloped.

Theprimaryelectronicinstrumentforwaterlevelmeasurementatthecombinedfeeddrum

waterbootwasaFisher2500pneumacleveltransmier. Thisinstrumentwasfoundtobe

defecvewhentestedduringtheinvesgaon. Historicaldatafromtheinstrumentwas

reviewedandconfirmedthattheinstrumentwasdefecveonNovember26,2013.

Asightglassservedasasecondaryinstrumentforthewaterlevelmeasurementinthe

combinedfeeddrumwaterboot. Thissightglasswasoperaonal,butwasdifficulttoread

becausetheappearanceofwaterandpolyfeedarenearlyidencal.

5. Thawingproceduresshouldberevisedtoensureallareasareaddressedsystemacally,especially

deadlegs.

Thawingprocedureswereinadequateinthattheydidnotsystemacallythawallvulnerable

locaons. Thawingrelieduponoperatorknowledgeandmemoryofvulnerablelocaonsas

opposedtoadocumentedandsystemacapproach.

6.

CRC

should

adopt

the

deadleg

defi

ni

on

set

out

in

the

American

Petroleum

Ins

tute

standard

570

andensurethisdefinionisunderstoodacrosstheorganizaon.

Inthecourseoftheinvesgaondifferinginterpretaonsofwhatconstutesadeadlegwere

apparentatCRC.


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7. Deadlegsinpipingshouldbesystemacallyidenfied,documentedandeliminatedorotherwise

migatedwhereverpossible. Deadlegsthatmustremainshouldbehighlightedandgivenspecial

aenonthroughoutoperaonsandmaintenanceacvies.

Thedeadlegonbypassline123BPLallowedwatertobecometrapped. Thiswatersubsequently

frozeandrupturedtheline,causingthehydrocarbonleakandexplosionofDecember24,2013.

8. Maintenanceproceduresshouldberevisedtoensurethatcricalsensingandmonitoring

equipmentremainsfunconal.

TheFischer2500pneumacleveltransmieratthecombinedfeeddrumwaterbootwas

foundtobedefecve.

9. CRCshouldsystemacallyidenfywhereinstalledpipingdiffersfromthedesignspecificaons. The

differencesshouldbeanalyzedandsuitablyaddressedasnecessary.CRCshouldinvesgate

whethercorrosionsurveydatacouldbeusedtoidenfywherepipingdoesnotconformtodesign

specificaons.

Althoughnotacauseofthisincident,inthecourseoftheinvesgaonbypassline123BPLwas

foundtobe2Schedule80,whiledesigndocumentsspecifiedthislinetobe2Schedule160.

2Schedule80hasawallthicknesswhennewof0.218,whereas2Schedule160hasawall

thicknesswhennewof0.344.

Thicknessmonitoringlocaons(TML)onbypassline123BPLwerelocatedatthetopelbowand

theboomelbow,bothlocaonsbeingwellawayfromtherupturedarea. CRCthickness

monitoringdataofOctober29,2013showsawallthicknessof0.220atthetopelbowanda

wallthicknessof0.200attheboomelbow.

10.CRCshouldreviseitscorrosionsurveyprocedurestoassesscorrosionunderinsulaon(CUI)on

jacketedandinsulatedcomponents. Thecorrosionsurveyproceduresshouldulizemethodsto

idenfyandassessareaswherecorrosionisthegreatest.

Althoughnotacauseofthisincident,significantexteriorcorrosionwasfoundonbypassline

123BPL. Bypassline123BPLwasjacketedandinsulated.

Datafromthicknessmonitoringlocaons(TML)onbypassline123BPLdidnotdetectthe

exteriorcorrosionthatwasfound. TheTMLswerenotlocatedattheareawheretheCUIwas

found.

CUIonbypassline123BPLresultedinawallthicknesslossofupto27%.

Theplacementofsteamlancesinsideinsulaonjacketsforthepurposeofthawingfrozenlines

isacommonpracceatCRC,andthismayplayaroleinCUI.


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GLOSSARYOFTERMSANDABBREVIATIONS

BPDbarrelsperday

BypassLine123BPLThe2polyfeedbypasslinelocatednearthenorthsideofpolymerizaonreactor#2. Thisbypasslinedivertspolyfeedflowaroundpolymerizaonreactors#1,2and3.Thisbypassline

isdesignatedonCRCdrawingsas27P1070FA5A2IH.

CRC CoopRefineryComplex

CUICorrosionUnderInsulaon

DeadlegsComponentsofapipingsystemthatnormallyhavenosignificantflow.Someexamples

includeblankedbranches,lineswithnormallyclosedblockvalves,lineswithoneendblanked,

pressurizeddummysupportlegs,stagnantcontrolvalvebypasspiping,sparepumppiping,levelbridles,

reliefvalveinletandoutletheaderpiping,pumptrimbypasslines,highpointvents,samplepoints,

drains,bleeders,andinstrumentconnecons.

FCCUFluidCatalycCrackingUnit

PMUPolymerizaonUnit27

PSIGPoundspersquareinch,gage. Ameasureofpressure.

RFPSReginaFireandProtecveServices

TMLThicknessMonitoringLocaon

TSASKTechnicalSafetyAuthorityofSaskatchewan

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Christmas Eve refinery explosion cause by frozen, ruptured pipe