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COMMODITY PIPELINE OCCURRENCE REPORT

CRUDE OIL PIPELINE RUPTURE

INTERPROVINCIAL PIPE LINE INC.LINE 2 (34-INCH DIAMETER), MILE POST 717.5

NEAR ST. LEON, MANITOBA

03 OCTOBER 1994

REPORT NUMBER P94H0048

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The Tr anspor t at i on Saf et y Board of Canada ( TSB) i nvest i gat ed t hi soccur r ence f or t he pur pose of advanci ng t r anspor t at i on saf et y. I ti s not t he f unct i on of t he Boar d t o assi gn f aul t of det er mi ne ci vi l

or c r i mi nal l i abi l i t y.

COMMODITY PIPELINE OCCURRENCE REPORT

CRUDE OIL PIPELINE RUPTURE

INTERPROVINCIAL PIPE LINE INC.

LINE 2 (34-INCH DIAMETER), MILE POST 717.5NEAR ST. LEON, MANITOBA

03 OCTOBER 1994

REPORT NUMBER P94H0048

Summary

Fol l owi ng t he st ar t - up of Li ne 2B af t er t he compl et i on of schedul edmai nt enance wor k at Cr omer St at i on, t he I nt er pr ovi nci al Pi pe Li neI nc. ( I PL) l i ne r upt ur ed at Mi l e Post ( MP) 717. 5, r el easi ngappr oxi matel y 4, 000 cubi c met r es ( m3) of synt het i c cr ude oi l i nt oa cul t i vat ed f i el d. Appr oxi mat el y 2, 860 m3 of oi l was r ecover ed.

Ce r appor t est gal ement di sponi bl e en f r anai s.

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Other Factual Information

On 03 Oct ober 1994, mai ntenance work on Li ne 2 at Cr omer Stat i on( MP 595. 8) and Mani t ou St at i on ( MP 723. 93) , schedul ed wi t h I PL' s

Oi l Movement s i n Edmont on, Al ber t a, was car r i ed out . Mani t ou St at i onwas bypassed t o f aci l i t at e t he mai nt enance wor k. Li ne 2 i s oper at edas t wo pi pel i ne syst ems: Li ne 2A t r anspor t s cr ude oi l f r omEdmont ont o Cr omer St at i on wher e i t goes i nt o t ankage; cr ude oi l i s t akenf r om t ankage at Cr omer St at i on and t r anspor t ed on Li ne 2B t oCl ear br ook, Mi nnesot a, U. S. and Super i or , Wi sconsi n, U. S.

The bypass at Mani t ou Stat i on di d not r equi r e t he cl osur e of t heLi ne 2 sect i onal i zi ng val ves at t hat st at i on. However , t he Mani t ouSt at i on per sonnel l ocal l y cl osed t he Li ne 2 sect i onal i zi ng val vest o car r y out addi t i onal wor k t hat had not been schedul ed wi t h Oi lMovement s. Al t hough t he f i el d per sonnel ver bal l y advi sed t he I PLCont r ol Cent r e Oper at or ( CCO) i n Edmont on of t he addi t i onal val ve

cl osures, t he CCO was not awar e of t he nat ur e of t he val ves nor di dt he CCO document t hi s di scuss i on. The CCO had known about t heschedul ed Mani t ou St at i on bypass work and bel i eved t hat t headdi t i onal val ve cl osur es wer e par t of t he schedul ed oper at i on andwoul d not have an i mpact on a l i ne st ar t - up. The CCO di d not r eal i zet hat t he val ves wer e mai nl i ne sect i onal i zi ng val ves whi ch woul d havet o be opened bef or e a l i ne st ar t - up coul d be i ni t i at ed. One of t heval ves coul d be r emotel y operated t hr ough t he Edmont on Cont r ol Cent r e( Cont r ol Cent r e) ; i t s st at us was t her ef or e di spl ayed at t he Cont r olCent r e. The ot her val ve was a hand- oper at ed val ve and i t s s t at uswas not di spl ayed at t he Cont r ol Cent r e.

Appr oxi matel y seven hour s af t er Li nes 2A and 2B had been shut down,t he CCO was not i f i ed by f i el d per sonnel t hat t he wor k at Cr omer St at i onhad been compl eted and t hat Li ne 2B coul d be re- st ar t ed. I n accor dancewi t h I PL' s st ar t - up pr ocedur es, t he CCO vi sual l y checked t he val vest at us of Li ne 2B. Al t hough t he CCO not i ced t hat t he st at us of t hesect i onal i zi ng val ve at Mani t ou St at i on was "unknown, " t he CCO knewt hat t he power had been di sconnect ed f r om t hat val ve and t hat t hi swoul d have r esul t ed i n the "unknown" st atus. Si nce t he CCO knew t hata l i ne st ar t - up coul d be i ni t i at ed whi l e Mani t ou St at i on was st i l lon t he schedul ed bypass, t he CCO began t o st ar t up Li ne 2B.

The CCO not i ced a pressure bui l d- up upst r eam f r om Mani t ou St at i onand t ook act i on t o r educe t he pr essure i n t he l i ne. A pr essure bui l d- up

woul d be expect ed dur i ng l i ne st ar t - up condi t i ons. However , i n spi t eof t he cor r ect i ve act i on, t he di schar ge pr essur e at Gl enbor o St at i on( MP 685. 55) spi ked t o 1, 127 pounds per squar e i nch ( psi ) , i mposi ngst r esses of between 110 and 115 per cent of t he speci f i ed mi ni mumyi el d st r ess of t he pi pe at MP 717. 5.

I PL has t wo l evel s of over pr essur e pr ot ect i on: a l ocal l evel at t hei ndi vi dual pump st at i ons and a syst eml evel at t he Cont r ol Cent r e.Speci f i c oper at i ng condi t i ons woul d cause t he over pr essurepr ot ect i on t o be act i vat ed. These condi t i ons, however , wer e not

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pr esent on 03 Oct ober 1994, and the over pr essure pr otect i on was notact i vat ed.

Si nce Mani t ou St at i on was st i l l bei ng bypassed dur i ng t he l i ne

st ar t - up, i t was t r ansmi t t i ng pr essur es of 0 psi t o t he Cont r olCent r e. Al t hough t hese pr essures wer e i nval i d f or l eak det ect i onpur poses, I PL' s Nor mal i zed Di f f er ent i al Fl ow ( NDF) l eak det ect i onsystemwas such t hat i t cont i nued t o cal cul at e f l ows i n Li ne 2 usi ngt hese pr essur es.

I PL i s i n t he pr ocess of upgr adi ng i t s Syst em Cont r ol and Dat aAcqui si t i on ( SCADA) syst em. The t wo syst ems ar e r un si mul t aneousl ywi t h t he i nf or mat i on di spl ayed on moni t or s at t he CCO' s wor kst at i on.On 03 Oct ober 1994, t he CCO was ver i f yi ng al arms generat ed by t henew SCADA syst em. Al t hough al arms were al so bei ng gener at ed by theol d SCADA syst em, t he CCO was acknowl edgi ng t he al ar ms but notver i f yi ng t hei r or i gi n. Thi s was a common pr act i ce si nce i dent i cal

al arms were generated by both syst ems wi t h t he except i on of t hosegenerat ed by t he NDF l eak detect i on syst em. The al arms generatedby t hat syst emappear onl y on t he ol d SCADA syst em.

The NDF l eak det ect i on syst em gener at ed al ar ms advi si ng of f l owanomal i es between Cr omer St at i on and Sour i s St at i on ( MP 646. 23) .These al ar ms wer e among t he many al ar ms normal l y r ecei ved dur i ngl i ne st ar t - up. Si nce t he CCO was oper at i ng t he pi pel i ne usi ng t henew SCADA syst em, t he CCO acknowl edged the f l ow anomal y al ar mwi t houtchecki ng i t s ori gi n. The CCO at t r i but ed al l al ar ms t o changi ngoper at i ng condi t i ons dur i ng l i ne st ar t - up.

The CCO cont i nued wi t h Li ne 2 st ar t - up procedur es unt i l advi sed byMani t ou St at i on per sonnel t hat , al t hough t he st at i on suct i on val vewas cr acked open t o f l ood t he st at i on pi pi ng, t her e was no pr essur e.A l i ne shut - down and i sol at i on wer e i ni t i at ed. However , f ol l owi ngdi scussi ons bet ween Cont r ol Cent r e per sonnel , Mani t ou St at i onpersonnel and t he Manager , Cent r al Regi on, a deci si on was made t hatt he l ack of f l ow at Mani t ou St at i on was based on an i ncor r ect val veal i gnment at t he st at i on as wel l as f l ow condi t i ons bet ween Mani t ouand Gr et na St at i ons. A Li ne 2 st ar t - up was agai n i ni t i at ed.

Dur i ng t hi s st ar t - up, t he CCO r equest ed a Mani t ou St at i on bypasscl osur e t o ver i f y l i ne i nt egr i t y. When t he pr essur e at Gl enbor oSt at i on di d not r espond t o thi s cl osur e, a l eak was suspect ed and

a l i ne shut - down was agai n i ni t i at ed and compl et ed.The l i ne was sect i onal i zed ar ound t he suspect ed l eak ar ea and I PLper sonnel began t o sear ch f or t he l eak si t e. A r esi dent of t heSt . Leon, Mani t oba, ar ea r epor t ed a cr ude oi l smel l and t he f ai l edpi pe was l ocat ed at MP 717. 5.

The TSB Engi neer i ng Br anch det er mi ned t hat t he pi pe r upt ured i nover st r ess at an ar ea of ext er nal cor r osi on. The cor r osi on ser vedonl y to l ocat e t he f ai l ur e i ni t i at i on poi nt when t he pi pe was

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over pr essur i zed, and woul d not have bur st had t he l i ne cont i nuedt o oper at e under nor mal pr essur e.

The j oi nt of pi pe t hat cont ai ned t he f r act ure i ni t i at i on poi nt had

been excavat ed, exami ned and recoat ed twi ce bet ween 1990 and 1993i n accor dance wi t h I PL' s pr ocedur es f or cor r osi on assessment .Cor r osi on di scover ed dur i ng a 1989 i nt er nal i nspect i on was not sever eenough t o warr ant r epai r and t he pi pe was r ecoated i n 1990. Ther ecoat i ng i n 1993 was compl et ed on a 3. 04 kmsect i on of l i ne as par tof a r ehabi l i t at i on pi l ot pr oj ect under t aken by I PL t o det er mi net he possi bi l i t y of r ehabi l i t at i ng an i n- ser vi ce cr ude oi l pi pel i ne.An i nt ernal i nspect i on i n 1993 i ndi cat ed t hat t her e was no gr owt hi n cor r osi on f r om t he t i me i t was f i r st eval uat ed i n 1989.

Analysis

The I PL pi pel i ne cont r ol syst emdoes not have sof t war e cont r ol s t oensur e t hat a l i ne st ar t - up cannot be i ni t i at ed agai nst a cl osedmai nl i ne sect i onal i zi ng val ve. Rat her i t i s l ef t t o t he CCO t o conf i r mt hat al l mai nl i ne val ves have been opened and t o i ni t i at e a st ar t - uponl y af t er al l ver bal and wr i t t en conf i r mat i on has been r ecei ved.

Al t hough t he CCO had been i nf ormed ver bal l y of t he val ve cl osur eat Mani t ou St at i on, t he CCO bel i eved t hat i t was par t of t he schedul edbypass and as such woul d not have an i mpact on a l i ne st ar t - up. Bef oret he st ar t - up, t he CCO not i ced t hat t he sect i onal i zi ng val ve st at usat Mani t ou St at i on was i n the "unknown" mode. The CCO at t r i but edt hi s t o t he f act t hat t he power had been di sconnect ed f r omMani t ouSt at i on because of t he schedul ed bypass. Ther ef or e, when t he st ar t - upof Li ne 2 was i ni t i at ed appr oxi mat el y seven hour s af t er t he val vehad been cl osed, t he CCO di d not quest i on f i el d per sonnel on t heexact st atus of t he val ve. I f document at i on had been made as t o thenat ur e of t he addi t i onal val ve cl osur es at Mani t ou St at i on, t he CCOwoul d have been awar e that a l i ne st ar t - up coul d not be i ni t i at edunt i l t he val ves had been opened.

Findings

1. A schedul ed bypass at Mani t ou St at i on di d not r equi r e t he cl osureof t he mai nl i ne sect i onal i zi ng val ves at t hat st at i on.

2. Mani t ou St at i on per sonnel ver bal l y i nf or med t he CCO t hat t heywoul d be cl osi ng addi t i onal val ves at t hat st at i on.

3. The CCO assumed t hat t hese addi t i onal cl osur es were par t oft he schedul ed bypass operat i on and as such woul d not have ani mpact on a l i ne st ar t - up.

4. The CCO di d not document t hat t he mai nl i ne sect i onal i zi ng val veson Li ne 2 at Mani t ou St at i on wer e cl osed i n addi t i on t o t hoser equi r ed f or t he schedul ed bypass oper at i on.

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5. The CCO i ni t i at ed a Li ne 2 st ar t - up af t er concl udi ng t hat t hesect i onal i zi ng val ve at Mani t ou St at i on di spl ayi ng an "unknown"st at us was i n t he "open" posi t i on.

6. A 10. 18 kmsect i on of l i ne was over pr essur ed r esul t i ng i n ar upt ur e at MP 717. 5.

7. The r upt ur e i ni t i at ed at a cor r osi on pi t t hat had been r ecoat edi n 1990 and agai n as par t of a r ehabi l i t at i on pr oj ect i n 1993.The cor r osi on had not grown between r ecoat i ng i n 1990 and t her upt ur e i n 1994.

Causes and Contributing Factors

The r upt ure occur r ed because a l i ne st ar t - up was i ni t i at ed agai nst

a cl osed sect i onal i zi ng val ve r esul t i ng i n an over pr essur e si t uat i oni n a 10. 18 km sect i on of l i ne.

A cont r i but i ng f actor t o t he f ai l ur e i ni t i at i on poi nt was an ar eaof ext er nal cor r osi on whi ch ser ved onl y t o l ocat e t he f ai l ur ei ni t i at i on poi nt .

Cont r i but i ng f act or s t o t he l i ne bei ng st ar t ed up agai nst a cl osedsect i onal i zi ng val ve wer e the "unknown" st at us di spl ay f or t hat val veand t he assumpt i on t hat t he addi t i onal val ve cl osure at Mani t ouSt at i on was par t of t he schedul ed bypass and as such woul d not havean i mpact on a l i ne st ar t - up.

Safety Action

I n March 1995, a TSB Saf ety Advi sor y was f orwarded t o t he Nat i onalEner gy Boar d ( NEB) out l i ni ng pr obl ems i dent i f i ed dur i ng t hei nvest i gat i on. The Advi sory i ndi cat ed t hat t he NEB may wi sh t o r evi ewt he appl i cabl e communi cat i on and l i ne st ar t - up pr ocedur es as t her emay be ot her pi pel i ne l ocat i ons wi t h si mi l ar unsaf e condi t i ons andpr act i ces.

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This report concludes the Transportation Safety Board'sinvestigation into this occurrence. Consequently, the Board,consisting of Chairperson John W. Stants, and membersZita Brunet and Hugh MacNeil, authorized the release of this report

on 05 July 1995.