Nebosh Diploma UnitA

8/9/2019 Nebosh Diploma UnitA

1/14

Mexico City

14thNovember 1984

Boiling liquid expanding vapour explosion (B!"!# at $% terminal& ' )illed&

$lant *as being +lled ,rom re+nery 4)m a*ay& -rop in pressure noticed incontrol room . at pumping station& $ipe had ruptured&

/perators0 could not identi,y cause o, pressure drop as they had no gas

detection equipment& No emergency shutdo*n at that stage and release o,$% continued ,or about '21 minutes *hen gas cloud dri,ted to 3are stac)&

Causal analysis ,ailure o, overall basis ,or sa,ety including layout o, plantand emergency isolation ,eatures& 5ire *ater system *as disabled in initialblast& 6nadequate *ater spray systems did not )eep remaining storagevessels cool and ,ailed to prevent spread o, +re ,rom vessel to vessel& $lanthad no gas detection system and there,ore *hen isolation system *as

initiated it *as probably too late& 6nstallation o, more e7ective gas detectionand emergency isolation system could have averted incident& rac chaos asresidents tried to escape area hindered arrival o, emergency services&

***&hse&gov&u):comah:sragtech:casepemex84&htm
http://www.hse.gov.uk/comah/sragtech/casepemex84.htmhttp://www.hse.gov.uk/comah/sragtech/casepemex84.htm


2/14

Brent CrossCrane Collapse

;th died&

Causal analysis 2 crane modi+ed incorrectly

Human factors errors in manu,acturing and maintaining

crane& ?a,e *or)ing load indicator inoperative& ugsmanu,actured to *rong spec recognised during manu,acturebut no chec) against dra*ings& 6nspection revealed deviationbut inspector did not *ant to re@ect something passed byparent company& Aee)ly inspection not carried out in

presence o, operator and de,ective sa,e *or)ing loadindicator undetected& ecords o, inspection not completed byinspector but probably by someone retrospectively *ith the*ords good order againstD sa,e load indicator&


3/14

Mar)ham Colliery

EthE

Material ,ailure to ,atigue& iding cage ,ell to pitbottom& 18 died 11 in@ured&

Causal analysis Bra)ing system su7ered ,rom a,atigue crac)& -irt in bearing bra)ing rod resultedin it being bent& Bra)e supposed to be ,ailsa,e&

Human factors Bra)ing system had not been

inspected ,or about 1 years prior to accident&6n,ormation on ,atigue had been ,ound at anothercolliery but not passed on& $oor design o, bra)ingsystem&


4/14

5lixborough !xposion

1st4

!xplosion caused by poor change management& ;8 died&

Causal analysis ,ailure o, pipe leading to release o, chemicalcloud that ignited&

Management deciencies inadequate procedures involvingplant modi+cations& !ngineers had no special expertise in highpressure pipe*or) . no proper dra*ings& $rocess *ith largeamount o, hydrocarbons under pressure above 3ashpointinstalled in area that could expose many to severe haFard&

Human factors $rimarily *ea) management& 6ndividualsover*or)ed and liable to error& here *as no mechanicalengineer on site o, sucient quali+cation status or authority todeal *ith complex and novel engineering problems and insist onnecessary measures being ta)en&D


5/14

ittlebroo) -D $o*er?tation

9th8

Material ,ailure due to corrosion& ?uspension cable on riding cage,ailed& Goist operated by contractor& 4 died&

Causal analysis ?uspension cable bro)e at point *ea)ened bycorrosion and devoid o, lubricant& Corrosion happened over shortperiod so not detected& Aater in sha,t contained salt adding tocorrosion& ?a,ety system did not operate as clamping mechanismsalso corroded&

Human factors need ,or stringent maintenance standards notrecognised by sta7 or management& ?tatutory =2monthly

inspections overdue& Aee)ly inspections ,ailed to see de,ects&Cage carrying more than recommended number o, passengers&Maintenance records not *ell )ept and exact regime could not bedetermined& ac) o, clear policies and procedures ,or contractor&


6/14

B$ %rangemouth

;;ndMarch 198>

!xplosion at hydrocrac)erD unit& 1 )illed&

Causal analysis air operated control valve on high2pressure separatorhad been opened and closed manually& iquid level ,ell and the valve*as opened allo*ing remaining liquid in separator to drain a*ay and ,or

high2pressure gas to brea) through into lo*2pressure separator andvessel exploded&

Human factors control valve did not close automatically as the extra2lo* trip on the high2pressure separator had been disconnected severalyears earlier operators assuming that these *ere no longer needed andtraining re3ected this& /perators did not trust main level control reading

and re,erred to a chart recorder ,or bac) up level readingH there *as ano7set on this recorder *hich led them to assume the level in the high2pressure separator *as normal& $ressure relie, had been designed ,or +rerelie, not gas brea)through& here *as excessive reliance on operators*ith inadequate appreciation o, ris)s associated *ith gas brea)through&


7/14

Illied Colloids

;1st


8/14

Aindsor Castle

;th/ctober 199;

5ire& -amage only&

Causal analysis heat o, a high2po*ered spotlightignited a curtain& 5ire spread quic)ly venting itsel,through the roo,&

6n the post2+re investigations it *as discovered thatthe rapid spread o, +re *as due to the lac) o, +restopping in cavities and roo, voids allo*ing the +re

,ree reign o, the building& his matter *as speci+callyaddressed in the restoration pro@ect and +re brea)s*ere placed into the void to avoid a similar disasterhappening in ,uture


9/14

Gic)son . Aelch

;1st?eptember 199;

5ire and explosion at ,actory batch still& ' )illed&

Causal analysis still base cleaned out ,or +rst timein E years& Geat *as applied to so,ten sludge&

Human factors decision to clean out still base *ithno prior testing o, residue and atmosphere in vessel&ac) o, communication bet*een operatives .management& Ibsence o, policies . procedures& 5ailure

to blan) o7 still base inlet be,ore *or) started&$resence o, building materials in control room impedingescape& 6n*ard opening door in control room& Goles inbric)*or) above ,alse ceiling o, protected routeallo*ing smo)e ingress into toilets *here one victim

*as ,ound& 6nadequate permit to *or) systems


10/14

$ort o, amsgate

14th?eptember 1994

Collapse o, passenger *al)*ay& = )illed&

Causal analysis ,ailure o, a *eld in a sa,ety criticalsupport element& -esign de+ciencies&

Guman ,actors no provision ,or ongoingmaintenance& -esign de+ciencies ignored by allinterested partiesH important environmentalconsiderations not addressed& ac) o, liaison bet*een

classi+cation society and designer:installer in ?*eden&Note ?*edish design:install company re,used to pay+ne&


11/14

Ilbright and Ailson

Erd/ctober 199=5ire and explosion at chemical storage site atIvonmouth -amage only&

Causal analysis tan)er believed to contain

epichlorohydrin o72loaded& ater ,ound to containsodium chlorite *hich reacts explosively *ithepichlorohydrin&

Human factors No chec) o, documentation

carried by driver *hich *ould have sho*ncontents o, tan)er& No preventative measures inplace to sa,eguard against addition o, materialreactive *ith substance already in storage tan)&

No ra* material control:sampling or operating


12/14

Bunce+eld /il -epot

11th-ecember ;'

5ire and explosion& -amage only&

Causal analysis pumping o, too much ,uel

into storage vessel& Iutomatic level gaugerecorded unchanged level despite continuedpumping& ich ,uel vapour ,ormed aroundbund ignited by un)no*n source&

Human factors reliance on automatedsystems *hich did not activate& 5ailure o,C/MIG procedures&


13/14

6mperial ?ugar

>th5ebruary ;8

-ust explosion at sugar ,actory %eorgia& 14 )illed&

Causal analysis sugar dust in enclosed conveyorbelt li)ely ignited by overheated bearing&

Human factors conveying equipment not deignedor maintained to minimise release o, sugar dust nor*ere there explosion relie, vents& -ust could easilyaccumulate and inadequate house)eeping resulted in

considerable accumulation o, combustible dust on3oors and elevated sur,aces throughout pac)ingbuilding& $revious sugar +res similarly causedalthough none had caused explosion or ma@or +re didnot result in managers or *or)ers recognising haFards

posed by sugar dust accumulationK danger had been


14/14

Banbury2?eer %reen

11th

-ecember 1981ail crash caused by human failure& E )illed&

6nexperienced signalman at %errards Cross miss2read or,ailed to comprehend indication on signal diagramHproceeded on assumption that loc)ed signal lever *as

,roFen and trac) circuit reading that line *as unclear *asactivated by ,allen branch ,rom passing stoc) train *hichin ,act *as stationary&

-river o, passenger train travelling too ,ast ,or conditionsa,ter being speci+cally *arned to ta)e care and to travel

bet*een '21mph& !stimated speed *as E'mph& Aas givenauthorisation to pass danger signal2 communicationbet*een driver and signalman may have been ambiguousand led to driver believing situation *as not serious&

-river and %uard o, stoc) train ,ailed to provide detonatorprotection to rear o, train but may not have had time

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Nebosh Diploma UnitA