H2S Manual - Shell

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and ProductionB.V. Exploration ShellInternational

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\ H2Sin Operations

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EP 95-0317

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HSE MANUAL

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I R e v i s i o n0 : 6 O c t o b e r 1 9 9 5

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EP HsE ManuarAmendment Recordsheet Section Number:Ep 95_0317 Section Tifle: H2S in Operations

Description of amendment

Originalhard copy and CD_ROilf-G

Contents

CONTENTS

ldentificationof Sources of HZS

2

3

Fluids 2.1 Process (SRB) Reducing Bacteria 2.2 Sulphate Assessment of Risks from HZS

3

5.1

Planning Emergency

25

5 . 1 . 1 E m e r g e n ce yquipment

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5.1.2 Procedurefor majorH2S release

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concernsfor H2S emission 3.2.1 Environmental and air qualitystandards

5.2.1 Hazards

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3.2.2 Dispersionin the surroundingatmosphere

5.2.2 Precautions

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3.2.3 Productionof sulphurdioxide

5.2.3 Generalprocedures/guidelines

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5.2

fety Effects of H2S

Guidelinesfor the Preparationof HZS Procedures

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6.'l

Formulation of Work Procedures

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6.2

Drillingand Well Operations

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6.3

Production Operations

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Control and Safe Working Practices

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The Framework of Controlsfor Workingin H2S Designated Areas

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6.3.1 Sampling 6.3.2 lsolation

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6.3.3 Depressurising

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4.2.1 The basisof classification

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6.3.4 Flushingand draining

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4.2.2 The effectsof dispersion

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6.3.5 Purging

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4.2.3 The classificationprocess

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H2S Detection

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4.3.1 Fixedsystems

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4.3.2 Portablesensors

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3 Personalmonitoringsystems 4.3.4 Testingand calibration

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WamingSigns

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AccessControls

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Permitto Work (PTW)

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Respiratory Protective Equipment

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4.7.1 The typesof RPE

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4.7.2 Protectionfor normalooerations

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4.7.3 Protectionin event of accidentalrelease scenanos

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4.7 4 Protectionin areas subjectto sulphatereducingbacteria(SRB)

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Procedural Controls and Standing Instructions

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H2SCompetence

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P 95-0317Revision0 5 October1995

6.3.6 Vessel entry

6.4 Maintenance Operations

33 34

Appendices I

Formation of H2S by SulphateReducing Bacteria(SRB)

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PhysicalProperties and Physiological Effectsof H2S

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H2SCorrosion

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Pyrophoric lronSulphide

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H2SDispersion

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H2S Detection

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RespiratoryProtectiveEquipment

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1.2 H2SAreaClassification

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4.9.5 Competencereview

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ironsulphide 3.3.2 Pyrophoric

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Recovery

3.3.1 Effectson metals

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4.9.4 Competencecertification

Firefighting

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5.1.3 Rescueprocedures

Effectsof H2S 3.2 Erivironmental

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4.9.2 Trarnrngprogramme

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3.1 HealthEffectsof H2S

1.3 ..

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4.9.3 Specificelementsof the trainingprogramme 22

Introduction

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4.9.1 Competencerequirements

HSE Manual Ep gs-O317Hydrogensurphide(Hzs) Vlll Typicalprocedures lX

Examplesof H2S AreaClassification Systemsin Use

in operations

59 A2

Gfossary

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References

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ii EP 95-0317Revision0 5 October1995

1 Introduction

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ffydrogenSulphideGIgS)is an extremely ciangeroussubstance,causingfataiiti ,".r. H.S occursfrequently in EP operations,it is consiclerednecessaryto cleclit

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The apploach is in line with the hazirds and effects supersedesEP S-SOOO-32. managementprocessdescribedin the HSE ManagementSystemEP 95-0300.

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fhe report describesfour steps:

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INTRODUCTION

of HoS exposure(Chapter'2) of all sor-rrces

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identification

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assessment of the risk to personnel(Chapter 3)

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controls and safe working practices (Chapter 4)

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recovery method.sin the event of loss of control (Chapter 5)

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Recoveryshould include contingencyplanning for all H"S-related situations (eg H:S leakage,evacuationprocedures,etc) \-

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It is of vital importance that these four steps are completedbeforeany work is r undertaken. The report is intended for use by field personnel in drilling, production and maintenance operations and does not cover design requirements for new plant.

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It does not add.ressdetails on the protection of the general public or the seiectio mabrials for HoS service.

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The Guideline provides the basis for the development of Opco specific procedure Chapter 6 gives some specific guidance on the preparation of H"S procedures fo: production, drilling and maintenance activities.

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Reference is made to Shel1 Safety Committee guide Hydrogen Sulphide, Hazard Precautions G,ef. 1). The reader's attention is drawn to the following:

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the rnajor hazard of HoS is its ability to cause rapid darnage to heal sudden death due to accidental exposure

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odour cannot be relied upon to detect the presence of dangerous .oncentrations of HoS

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50 per cent of the people killed in H,S incidents were trying to resc others.

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If the reader doesnot understand an)' part of this documentheishe must discussit wiih .omeone who d.oes.

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0 5 October1995 EP 95-0317Revtsron

of Sourcesof H2S 2 ldentification

2

OF HzS OF SOURCES IDENTIFIGATION

sufficient concentrations to Liquid and gaseous hyd,rocarbons may contain HrS in present a hazard to personnel, equipment and the environment' pipelines, desulphurisation piant's' HrS can be present in oil refineries, process plants, swamps, or any area oil/gas/water wells, during drilling or well workover, sewers, (eg utility shafts in offshore where there is decayrng organic matter or stagnant water platforms). when acid is used to ciean HrS can also result from acidicaustic reactions, for example which has been used caustic equipment containing iron sulphide or to neutralise spent flowed back after well t* HrS scrubbing. HzS may also be present in spent acid stimulation. to resist the harmful effects of All facilities potentially exposed.to HoS must be designecl pressures' HzS at the anticipated operating temperatures and HrS in the upstream oil and gas industry comes from: .

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2.1

material and the the original reservoir, as a result of the hydrocarbon source gas. If this is the case then H'S cond.itions under which it was converted to oil ancl will be produced with the fluids bacteria (SRB) stagnant seawater systems, by the action of sulphate reducing (seawater, brackish, the reservoir after proionged. injection of water with oxygen 'souring' it due to the within fluids the of formation water) which *ut result in will be HrS process. Any action of SRB introduced during the injection subsequentiy produced with fluids'

Process Fluids

in the process fluids arises : The risk to personnel on a facility where HrS is present o

during an accidental release

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entry, instrumentation during normal maintenance operations, eg./sphering, vessel or valve maintenance

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during venting from tanks'

upon the concentration of HzS The level to which personnel could be subjected d.epend.s local conditions. refer to 3'2'2, in the process fluidand the d.ispersion and d.ilution under d.ispersion in sur-roundin g atmosphere'

2.2 SulphateReducingBacteria(SRB) necessaryfor SRB SRBs are the sourceof a range of hazard.sinclud.ingHgS. Cond:tions of means (including H"S), to exist an6 d.evelop,hazarclsassociatedwith SRBs prevention, detectitn and control are ali describedin Appendix I'

EP 95-0317Revision0 5 October1995

3

3 Assessmentof Risksfrom H2S

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basedon broad basedconsequence This documentprovidesa set of recommendations analysisand operationalexperience. A full risk analysis may proviclea better insight into the potential frequency and of specificHoS related events and point to possiblerisk reduction consequences measures.Howe!'er, perioJs of highest risk may not always be predictable and 'HrS Risk recognisedand.it is advrseclto acloptthe recommendationsfor classificationof use the Areas,containedin this document.By doing so, procedures,including those for of protective equipment, will ensure the appropriate state of workforce awarenessand preparedness. 'HrS Risk Risks associatedwith incidents that may effect areas beyondthe classified Area, should always be assessedand this may even be a legislative requirement. Such parties risks may be to persons,for instance,in Opcofacilities or accommodation,third or the public (refer to 3.2.2). The threats presentedby HrS in a processand non-process,eg seweragethroughout the Iifetime of that facility or pi-pelinewill be recorded in the HSE Case together with the control measures.

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A S S E S S M E N TO F R I S K SF R O MH Z S

Health Effects of HrS

(ACGIH) The current American Conferenceof Governmental Industrial Hygienists (TWA) and 15 ppm 8h Threshold Limit Value (TL\ry is 10 ppm Time Weighted Average Short-Term Exposure Limit (STEL). or The major hazard of HrS is its ability to cause rapid damage to health sudden death due to accidental exposure' Brief exposureto concentrationsabove500 ppm may result in rapid unconsciousness without any warning symptoms.Exposule to HrS above500 ppm for any lenglh of time is considered.as potentially lethal. Death due to stoppageof breathing may follow within a few minutes unless the victim is removed to a safe atmosphere in time and possible in artificial respiration is applied..If the victim survives, complete recovery is most cases.Exposuresover 30 minutes to HzS concentrationsof 200 ppm and above may causer...,*r.lation of fluid in the iungs Oung oedema).At concentrationsabove of the l0 ppm, HrS can have an irritating effect on the eyes and the mucous membranes In low nose,throat an6 1ungs.The pr-imarysourceof exposureto HrS is by inhalation. concentrationsHrS has the odour of rotten eggs' at It must be emphasised.that the unpleasant od.ourof HoS, which can even be detected due ppm 100 above concentrationsof 0.02 ppm, may not be detectableat concentrations to rapid loss of the senseof smell. Odour cannot be relied upon to detect the presence of dangerous concentrations of HrS. The effect of H=S on the hoclyat clifferentconcentrationlevels and the occupational exposurelimits are shown in Appendix II' personnel at risk from exposureto H"S must be trained to know what to do if H"S is person has to be rescued.Such training is vrtal since to detected.or if an unconscior.rs 'conditioning'that might resuit in an someextent it is necessaryto controi the individual hur.r.vingimmecliatelyto the aiclof someoneovelcomeby H'S-

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EP 95-0317Revrsion0 5 October1995

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F H S E M a n u a l E P 9 5 - 0 3 1 7 H y d r o g e nS u l p h i d e ( H z S ) i n O p e r a t i o n s V

REMEMBER:50 PER CENTOF THB PEOPLEKILLED IN H.,S INCIDENTS\AIERETRITNGTO RESCUEOTHERS.

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3.2 G

EnvironmentalEffects of HzS

Emission controis should be set to protect people from toxic risks and avoid public nuisance. There are no known health effects associated with long-term exposure to HrS at concentrations at or below the point where short-term symptoms (for example eye or respiratory irritation) are observed.

3.2.1 Environmentalconcernsfor HzSemissionand air qualitystandards The air quality in respect of allowable concentrations of HoS varies considerably from country to countrS'. Alowable emission concentrations can be as low as 1 (one) ppm HrS with a corresponding air quality of 0.02 ppm HrS over a 30- (thirty-) minute period. These levels do not present a toxic risk although they can result in a pungent odour. The odour threshoid for HrS depends upon the individual and can be as iow as 0.02 ppm. Higher concentrations will most certainly cause odour ploblems.

3.2.2 Dispersionin the surroundingatmosphere Dispersion of gas containing H2S in the surrounding atmosphere depends on a number of factors: .

nature of the source of the HrS HzS in EP process operations will rareiy be present in pure form which is heavier than air, it will usually be a constituent of a process fluid such as produced gas, condensate or crude oil. (Simiiariy HrS encountered in non-process situations, such as sewerage systems will also be a constituent of a composite gas). Dispersion depends on both the nature of the process fluid (for instance a light gas will behave differently fi'om a dense gas) and the initial concentration of HoS in the plocess fluid.

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emission conditions If under plessure then process fluids containing HoS could be released to the atmosphele, for example, via a leak, weII services lubricator, maintenance or maloperation of a sampie vaive. The release pressule, duration, rate (with time), hole size, elevation and direction influence dispersion. Releases can also occur fi'om vaporising liquid pools.

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atmospheric conditions, wind speed and dilection A high pressule gas release rviil initially be diluted by air due to the turbulence of the jet, thereafter the ambient temperature and atmospheric stability become influencing factors. !\;ind speecl and dilection affect both the jet behaviout' and subsequent diiution.

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topography Dispersion is accelerateclovel mole buiIt, np or rvoodeclland. Given stabie weather' conditions a heaq;. gas rvill also tencl to accumulate in low lying areas thus the contours of the land. and plesence of. for,'instance, buncied aleas can influence dispersion.

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3 Assessment of Risks from H2S

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samPlingttme

time plym: fluctuate with time. A short sanrpling ciisper..sing a in concentrations sampie high exposureconcentrations,a longer in the dispersionmocrei*uy o"" exposure' time givesa more lealistic avelage Raciiation' using moclelswithin sIPNI's FRED 6ire' estimated be can rates Dispersion primariiy as a moclels.FRED has been rleveloped Exprosion.Dispersion)suite of thus is weli Assessmentstud.ies(seeEP 95-0352) screeningtool for euantitative Risk opco or is not available for use within an FRED where mod.elhng of type suited to this from nu."r.ury, aclviceshould be sought where specificcasestucliesu.J.or,riclered SIEP'

t . , 2t l ^ r . - clictated r r ^ + ^ + ^ . t 'by the maxrmum co n c e n t r a t i o n o f 'HnS Riskt At'ea' is an of The classification the Hzs to do harm is used othe, *or,r. the potu.rtiul for HrS in the process str.eam . In of the dispersion is that an accurate estimation acknowledgecl is it as criteria as the

difficult to Pledict' 10 ppm could occur that Hrs in concentrations above However. it may be possibre perhaps public or ,Hrs Risk Ar;" for example on a neighbouring, outsicle the classified necessitate the Determination of this risk may accommodation. or. faciiity party, thir.d aggl'egate risk to i.r.rrrairr* the calculation of the use of more rigorous eRA t".irniq..u. leak scenarios' RiskA'La'clue to the cred'ible the.I"rrifi"diHrs outside ind.ividuals neghgible region' a may be very low, perhaps in the Arthough this aggregate risk d'irection resulting in death cond.itions with irr" *i"d in a r.eleaseunder stable weather yardstick would the'efore be be feasible. A more suitable nevertheless could. effects or ill the d-istance to neighbouring d.istance oi irs r"^rT. to fix the use of the maximum effect in terms of effect gives an i.nd.icati6n of the consequences ar.easof concern. Table v. r 'worst case' dispersion scenarios' of distances of an arbitrary sel"ection in a comm'unity residents (eg infants, elderly) It shourd be noted that sorrre the working than Yrrore severely ;t lower levels around a plant rnay react population.

3.2.3 Productionof sulphur dioxide

and is also HZS is burnel i" the atmosPhere when formed products the of SOois one often Present in combination formed.whenpv'"pr'"ricironsulphicieoxidises.Itisalso with HtS.

_-.rr^^^+. gas (or liquid) with a strong suffocatrng non-flammabre Surphur d.ioxideis a colourless. in sputum and. causes coughing. an increase odour. It is a respiratory irritant at low concentrations. production and b,o,,choconstr.iction been set in order rimits for sulphur dioxicle have Recommend.edoccupational expos*re of Governmental The rggunggb American conference to prevent these acute symptoms. on an S-hour time (ACGI}I) Thr.eshord.Limit Value based. Ind.ustr.ial Hyelenists Limit is 5 ppm' 15-minute short Term Exposr'r.e weighted.average is 2 ppm.The

3.3 SafetYEffects of HzS 3.3.1 Effectson metals

conversei5'rvhetr be consicleleclto be nou-cor''.-osive' can watel' fi'ee of absence H,,S in the such zr'sstalt-upishr'rtclurLngabnorrnal situzttions' flJe rvater is plesent, especialiv u'iIl most probabl]' take lliacel' ottt a iircii' general con'osion circr'riating or d.rilling clown. present' either' ions ?l"nr"tttal sulphrtl' al'e If calbon d'ioxide. o]:ygen' chior"ide

7 1995 E P 9 5 - 0 3 1 7R e v r s t o0n 5 O c t o b e r

H S u l p h i d e( H z S )i n O p e r a t i o n s H S EM a n u a lE P 9 5 - 0 3 1 7H y d r o g e n inc iiy ic iua l l l ' o r to g e th e l th e n s e v e re col rosi on may take l tl ace w i thi n per . iod. F u rth e r. d e ta i l s a re g i v e n i n A ppendi x III.

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iron sulPhide 3.3.2 PYroPhoric pyrophoric iron sulphicle can be formeci on the internal surfaces of carbon steel equipment containing HrS. h'on oxiclepresent on the internal sttrfaces will react u the HoS ancl form p-r'rophoriciron sulphide which, on exposure to oxygen can autorgnitel This pr.ocessand the means to manage the hazard are detailed in Appendix Although pyrophoric iron sulphicle can folm and collect on ali internal surfaces of

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carbon steel equipment, likely places of accumulacions ale: Iubricatols (retrieval of wireline fishes, mill-scale from tubing) :

ff:"" vessels

pigreceivers \-

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storage tanks.

\\[ei]st steps can be taken to reduce the formation of pyrophoric ilon sulphide it m never be assumed that there can be an absolute prevention of the reactionTherefore any equiprnent constructed of carbon steel which is in contact iron sour hydrocarbons should be treated as if it contained pyrophoric sulphide. Great care must be taken on opening equipment likeiy to contain pyrophoric iron sulphide, for its removal, d.isposal,etc. For further detaiis see Appendix IV.

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EP 95-0317Revtsion0 5 October1995

4 Controland Safe Working Practices

CONTROLAND SAFEWORKINGPRACTICES

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working in H2s Designated 4.1 The Frameworkof controrsfor Areas

points in turn: by examining each of the following derived is contrors of The framework in what concentrations (Hzs Area . where is H2S likely to occur and Classification)

(Hzs the concentrations measured/monitored how wilt H2s be detectecl ancl Detection) presence of H2S (warning signs) what is needed to warn of potential (Access controls) to H2s d.esignated areas what is need.edto control access areas work is carried out in H2S designated what is needed.to control how (Permit to Work) must be carried/used- in H2s designated what protective breathing equipment Protective Bquiprnent) areas (Respiratory areas for access/work in H2s designated what procedural controls are required

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(Proceduralcoot"olsandStandinglnstructions) in H2S for personnel accessing/working o what competence levels are needed. in HZS procedures) designated areas (Competence used: on the type and extent of controls The following factors have a bearing entering (eg sampling from H2s-containing equipment, . the tylpe of work activrty vessels, etc) (ie degree of exertion) o the level of human activity reiative to potential H2S sources ' the location of work personnel rthenumbersofworkpersonnelinvolved(particularlylargenumbers) release . the potential for an uncontrolled or upsel out (eg shutdown/start up, concurrent . the type of operations being carried. oPerations)

effects of vibration' of equi.pment (eg leaks, cracks, the state of integrity of items etc) still cond.itions (eg inversion, wind the occurl.ence of abnormal atmospheric etc) conditions [often at night]' storm'

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the timing of wor-k (eg at night)

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(eg where personnel have to work in the workplace and access cond.itions o' with poor access)' crampedicongested cond'itions the necessaly controls are that: The key requirements in devising taken into account . all the factors are recognised and

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the appropriatecontlols are specified

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I EP 95-0317Revision0 5 October1995

H HSE ManualEP 95-0317HydrogenSulphide(HzS)in operations V

4.2

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HZSArea Classification

4.2.1 The basis of classification The classification of HrS areas should be based on rhe likelihood of HrS presencein the area and the rnaxirnum concentration of HrS that can be present.

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Likelihood of H"S presence is defined according to a range of possibilities between impossible (ie always below the Occupational Exposure Limit (OEL), of l0 ppm) ancl expected uncler expected operating conditions. The two leveis of significa"." i" determining how concentration contributes to alea classrfication are 10 ppm (the 1evel below which there ale no health symptoms - the OEL) ancl 200 ppm (the approximate dividing iine below which the effects of HrS cause minor/reversible symptoms and above which major/permanent physiological damage is causecl).

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4.2.2 The effects of dispersion In all work situations (except those involving confinecl spaces and entry into equipment) some dispersion will occur when HoS-containing fluids are released..Gas leaks-from equipment under pressure can be considerably cliluted in a short d.istance by jet entrainment of the surrounding air (even when pressures are very low, say 0.1 kpa). The probability of inhaling undiluted process B&s, if an accidental leak occurs, is extremely low and in principle a d'ilution of e0 to 30 times can be assumed within 100 diameters of the outflow. However the consequences of an accid.entcausing exposure to high levels of HrS are extremeiy serious and it is not acceptable to ignore this small but significant risk. For example, an exposure, to 1000 ppm HrS in air, ho*"17"r brief, is Iikely to be fatal unless rescue and resuscitation are immed.iate. For this reason the maximum level in a gaseous process stream, for which the health risk can be truly considered minor in the event of an accidental leak, is 500 ppm. Even this level needs to be qualified because there are types of gaseous release in which no dilution occurs: ' .

the release of heavier than air vapours (> 1.05 x d.ensity of air) from a liquid spill an atmospheric vent at very low velocities.

Light sour condensate is probably the worst in this respect. 00 nqm HrS in the process (or 200 ppm if significant hearry vapour release is possibie) f is the limit above which the HoS concentrations in air are likely to ,"rult in *"io, symptoms, causing permanent physiologicat damage. At the iower end of the scale 50 ppm in a plocess stleam is recommended as the levei below which an accid.enrai leak is unlikely to cause any noticeable toxic effects of health hazard significance. Accurate estimation of the dispersion to detelmine HnS concentration at particular a location remains difficult. For this reason it i.s lecomrrjrendedto base the use of protective equipment on the maximum concentlation of H"-s in the process stream rather than in air'. Table 4.l summarises HrS concentrations i.rproless gas streams, derived maxima in air. the effect on expo.ud vicrims ancl the required. action in the event of exposure.

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4 Controland Safe Working Practices Table 4.1

H2S concentrations and the effectson exposedvictims

H25 concentration limit in gaseous

Derived maximum H2S concentration in air (ppm)

Effect on victim

Required action for victim

>500

R api dunconsci ousness. Deathoccurswithin minutes

200 to 500

Maj orsymptomscausi ng permanentphysiological damageor death.R api dl ossof senseof smel l .Lungoedema afterabout 30 minutes' exposureand may stilloccur some time after rescue Minor,reversiblesymptoms such as irritationof eyes,nose, throatand lungsfrom exposure for maxi mumof 10 mi nutes. A t 100 ppm senseof smel ll ost w i thi n3 to 15 mi n. A t 200 ppm senseof smell lost raoidlv. Occupationalexposurelimit(for 8 hr exposure,ACGIH documentationof TLVs). Settinqon HzS alarm svstems No svmptoms

Removalto safe atmosphere. Artificialrespiration Removalto safe atmosphere. Artificialrespiration

Process streams (ppm)

>500

<500

10to 200

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<50

<10

Removalto safe atmosohere

N one

None

'Hydrogen Sulphide' 1986) @eferenceShell Safety Committeepublication G,ef. 1). See also Appendix V.

4.2.3 The classificationprocess The sequenceto be followedin determining HrS area classificationis shown in Figure 4.1.

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HSE Manual EP 95-0317HydrogenSulphide(HzS)in operations Figure 4.1 HrS area classification

ldentifyH2S sources, collectand analYse praess/f acilitiesdata, establishrelease mechanisms

H2S-freezone

concentrationin air <10 ppm under all

presencepcsible duringnormaloPerating conditions?

DerivedH2S conccntrationin air <200 PPm?

air may As shown in Figure 4.1, all areas where the H'S concentration in marked be be designated Hrs risk areas. They should exceed 10 pp*in"u minor or upon a dejicated set of drawings together with the associated risk: rnajor. plesence is expected, Note: During d.riiling or workover operations in areas where HrS precautions as for the the level of exposure cannot be accurately pred.icted.In that case' highest level of accid.entalexposureshould be undertaken. be pr:esent For exploration driling in new areas it should ahvaysbe assumedH"S may and precautionsestablishedaccordingly'

4.3 HZSDetection personnel against The objective in HoS detection is to provide early warning to caution HSE precautions' entry into a kno*ri hazardous area without taking the appropriate Amongst the key points in defirung a detection system are the following: .

it should exhibit fail-safe design

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it should be specific for HrS

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EP 95-0317Revision0 5 October1995

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4 Controland Safe Working Practices .

it should have detectors close to all potential sources of leakage.

Only equipment specifically developed for the detection of HrS will achieve the clegreeof responsenecessary to alert personnel. It is important to be aware that all detector systems have an in-built delay between HrS release and its detection, due to the response time of the system and its components.

WHEN A}.I HzS ALARM IS SOUNDED THE GAS HAS ALREADY BEEN PRESENT FOR SOME TIME AND I\{AY HA\M ALREADY REACHED DANGEROUSCONCENTRATIONS! 4.3.1 Fixed systems No matter how well designedthe facihty and how good the stand.ard.of operation an4 maintenance,the possibility of accidentalreleaseof HoS cannot be totaliy discounted.. For this reasonit is recommendedthat HrS detectionsystemsbe installed.in high HoS risk areas,defi.nedas those where: '

the processcontains gaseswith HrS concentrafionsin excessof 1.0 per cent volume (10,000ppm) or

o

liquids with HrS contents which could glve rise to comparable H"S emissions with the resultant possibility of a major hazard occurring outside the facility bound.ary.

However, considerationshould also be given to installitrg HrS detection systems where such concentrationsexceed0.1per cent volume (1,000ppm), particularly where dispersionof leaked gas could be hindered or where escapeis difficult, as for example offshore. A fixed system does not in itself provide protection for personnel. It shouid.not therefore be considereda substitute for normal entry precautions to a high risk area, where tests using portable equipment and carrying of breathing apparatus should be part of procedurefor entry. The basic requirement is a system of sensorslocatedwhere HrS is most iikely to be releasedto the atmosphere or accumulate. For further details on the design of fixed. detection systems, refer to Appendix VI where relevant sections of SSC guid.eline 'Hydrogen Sulphide,December1986' (Ref. 1) have been included for easy reference. Refer also to DEP 32.3I.20.11-Genffi,ef.2) for further detail concerning the selection, location, installation and calibration of fixed HrS detection systems. It should be noted that high concentrationsof H,S in small volumes mav be insufficient to trigger the HrS detectionsystem.

4.3.2 Portablesensors In addition to the fixed HzS detection systems, portable sensors are used.for alerting the individual and should be availabie to designatedpersonnel.They may be used.in locationswhere it is not practical to install fixed sensorsand can also pror.ideback-up facilities in the event of a fixed system failure. These d.evicesusually glve an aud.ibie and visual warning if a preset levei is exceededand pro'"ide the ability to have a continuousread-outof the concentration.

EP 95-0317Revision0 5 October1995

13

sulphide(HzS)in operations HSE ManualEP 95-0317Hydrogen of the portabie lnventories and the aliocation foliowing: .

OperatingManual

.

EmergencyProceduresManual

.

ContingencYPlans'

in the d,etectorsshoulclbe clescribed

operation and suitable continuous and automatic in be should. provided The instrument audible (and' instrument should give " tl"ut The p"r.orrrer. for use by non-technicar UrS at the pre-selectedconcentration' visual) alarm in the pr"r.rr.. "i In add-itionthe instrument should: .besuitableforuseinhazardousal.eas(mandatory)

.

be robust in construction and operated by one person be capableof being easily hand.Ied eight hours rechargeabre,rasting at least have a integral power source,

.

have test function caPabilitY

.

be easy to calibrate

r

alarm on failure'

' .

4.3.3 Personalmonitoringsystems

is exceeded' used to-wa.rn that a preset level personarHrs monitoring systems are_only as testers' de*ri.". ,ro, should they be used gases They are not meant to be ,i""rrrring diffusion characteristics of toxic personal monitoring ,yrt"*, are based.on the which generate-san electric current Juctrochemi.ur-J"r"ctor "r and usually incorporate an audible or visual This current is converted into as the toxic gas passes over it. a personal H2S monitor to be consideredin selecting Th" (or both) ;"rnts signal dispray ur" d."t.ribed in APPendix VI' is made fully d.escribedabove is that the operator monitors the using for has to be A prerequisite the equipment and of what action rimitationsof and. aware of the capabilities sensing head should'never be being tri#red alarm the 'poison' most of lt event the in taken of HrS will quicklv Higii*ar "ti;;it"*.. or clothing by shieided personal monitors'

4.3.4 Testingand calibration

the manufacturer's be tested.in accordancewith shouid. equipment and systems AII strict application of ,;;;1;$r, "rtuuii.h"d. tt"ough maintenance the or recommend.ations depending on the particular 6cno ilethod'oiogy the Reliability centred rvr^irrt"nance The functioning situation-BecauseHosdetectionsystemsarep'i*u'iif*u"'i"gd'evices'notonlythe speed.of '..porr.e of the sensor' the also urrt verifiua be accur.acyshould devrces'operator as visual beacons.audible warning such parts system-related. the of at i'egttlat intervals and and.arike should also be verified ."rrtre controt the in to interfaces shourd.be given to accessto detectors consid.erurron Due ,rr". of beforeeachperiod 'estrlts of rvhich should be testing and calibration, til" maintenance frequent enabre recolded. VI' For further details seeAppendix

14

1995 EP 95-0317Revision0 5 October

4 Controland Safe Working practices

4.4 Warning Signs It is important that all equipment containing H"S is clearly marked, with vesselsand pipelines individually identified. This is in addition to area warning notices which should be in all working languages.In some countries a national standard is available and in somelegislation clearly definesthe colour coding for processequipment and pipework containing HrS in hazardousconcentrations.

r

fif,H:T::Tffi"ff,*H'$5;fttTilHffi::;*,:iT;:l;,m

'I

level of training should also be marked by appropriate signs and markers. Signr pictorial content are preferred to text only.

Ij

The following may be used as references: ISO 3864 Safety Signs and Colours equivalent to BS 5378 @efs. 3 and 4) BS 1553 Specificationof graphical symbols for general engineering @ef. 5) SSC Safety Signs and Colour Coding September 1981 G,ef. 6) API RP 49 RecommendedPractice for Safe Drilling of Wells containing HoS G,ef. 7)

\-

4.5 AccessControls Procedures must be in place for access,escape and movement control of personnel in HzS designated areas. These should include: .

inform the person in charge of the nature of your activities

.

all personnel should sign in and out at a central control point, outside the area, where competency certifi.cates are checked

o

special instructions concerning the work location, (normal access and escape routes, wind direction)

.

use of calibrated portable HrS detection equipment

I

use of escape or BA sets

o

working singly or in pails

.

radio communication

o

special production supervision for non-HrS trained personnel as required, eg construction workers. dr-ivers, etc.

The procedures may vary for different tpes of iocation (eg onshore or offshore) but should be prepared for the different activities which have to be performed.

4.6 Permitto Work (PTW) A PTW should be issued fol any work to be carried out in H,S plant areas. As with any requilement for hazardous rvork. it is necessary-to establish the level of risk to the persons involved before defirung the necessary contlols and should address: o

satisfactory communication for al'ea or confined space entry

.

personal HrS monitors ro be worn

EP 95-0317Revision0 5 October1995

15

HSEManua|EP95-03lTHydrogenSulphide(HzS)inoperations job, together pointecrout to personsdoing the wind,sockstrategicalrysited and instructions as to where to escaPe

with

positioned adequatearea warning signs osCCesscontrolrequirementasdescribedin4.5 tag board o us€ made of personaltags and central for the type of environment encountered r acld.itionarprotective clothing provided person and positioned correctly o safety equipment checkedby a competent lines BA; portable d.etector;belts and life ie compressedairrine BA; self-contained to a piece of equipment required.;positive isolation of aII lines 8) r eotry into a confined space(seeRef' waterwetting of any possible For example: removar of pyrophoric sludge/debris_and no entry if H2S above and 02 levels; residues; gas testing ro, fl"*mable, to,.J then lower HzS limits may be L0 ppm (if escapeis particularly time consumin! if possible' consider"at' rr"th air flow to be established o frequency of testing for HoS and by whom .retestingforHzSpriortorestartinganyworkperiod greater degree of dilEculty where it cannot . for work of an increased.time scale or wil remain below 10 ppm' The wearing be guaranteed.that the averageHos level shourd.be stipulated. (A11possible of a compressedairline breathing upp^r"tus of be und.ertakenbefore the extensive usage steps to gas free the equipment ,rrorrra BA is accePted)' full Hos protection): NO ENTRY (exceptin emergency,with not even if flammable vapours or H2S are o if the confined spaceis being inerted, Present

10 ppm or more of H2S vapours' if the confined.spaceis known to contain ventilation should be applied' In both these circumstancesfurther d'escribedin EP 95-0315' Permit to Work generic guidelines are

.

16

EP 95-0317Revision0 5 October1995

4 Controland Safe Working Practices

4.7

Respiratory Protective Equipment

4.7.1 The types of RPE Table 4.2 summarisesrespiratory protective equipment and its application. Seealso Table\TI.1. Table4.2

1t I

\

protective Respiratory equipment

Typeof Apparatus

Description

Application

Self*onta ined breathi ng apparatus wlth full face mask

Compressedair cylinderscarriedon wearer'sback supplyfull face mask throughflexiblehose

'Positivepressure' mode recommendedfor H2S-

'Positivepressure' mode minimises pullingtoxicvapouraroundseal of face mask

contaminatedenvironmentup to a max. 20,000ppm (2%) H2S Duration30 or 40 min dependingon cylindercapacity Suitablefor escape

Compressedairline breathing apparatus with full fuce mask

Compressedair from remote cylindersupplyor compressorfed to full face mask throughflexiblehose

'Positivepressure' mode with cylindersrecommendedfor H2Scontaminatedenvironmentup to a max. 20,000ppm (2%) H2S Directsupplyfrom a compressoris less reliableand not recommended Not suitablefor escaoe

Combination of self-contained and airline breathing apparatus (cascade system)

Self-contained breathingapparatus with compressedair cylinderand provisionfor connectinginto

As for compressedairlineabove but also suitablefor escaoe

compressedair supply Emergency escape BA sets with full face mask

Type | - Smallcompressedair cylindercanied in jacket pouch/ shoulderstrapsuppliesfull face

Duration10 or 15 minutes dependingcylindercapacity

mask throughflexiblehose'Positive pressure'mode prefened Type ll - Clearplastichood sealedat neck.Air suppliedfrom cylinder throughflexiblehose Chemical canister respirators

Full face mask or mouth/nose assemblyconnectedto canister (containingH2S absorbent chemical)by flexibletubing

EP 95-0317Revision0 5 October1995

Duration5 to 15 minutes Easy to put on Only to be considered for use for escape purposes subject strictly to conditions descrlbed in Appendix Vll

17

HSE Manual EP 95-0317HydrogenSulphide(HzS)in Operations

4.7.2 Protectionfor normaloperations Depending on the H"S at'ea classification and the circumstances that influence the extent and level of controls (see 4.1 and 4.2), the foilowing levels of personal protection are recommended: Table 4.3

Protectionlevelclassification

Level of protection

Description of protection

A

Monitoronly

B

Monitorand escapeBA set to hand

c

Monitorand escapeBA set mask at the ready

D

Monitorand BA set to hand

E

Monitorand BA set mask at the readY

F

Monitorand BA set with mask fitted

Definitions of the terms 'at the ready' and 'at the ready' .

.

'to hand' are as follows:

For work closeto a potential sourceof leakagethe mask should be hangrng from the neck 'at the ready'. 'to hand'

For work further removed from a potential source of leakage having the mask ready, nearby and in the line of escapeis sufficient. 'standby' should always However, a potential rescuer and/or the buddy on 'at the ready' and use a BA set. have his mask hanging In areas where HrS is normally present (refer to Figure 4.1), Ieve1F shall always apply. In areas where HzS presenceis quite possible first entry shall always be made with protection at level F. Only once the area has been made safe can the level of protection be reduced,eg to level B. A BA set may either be self-contained,or air hose supplied.Where an escapeBA set or BA is to be 'to hand', reliance may be put on strategically placed communal sets. Individual allocation of sets is, however,preferred to avoid the risk of confusionin an emergency.If appropriate,safety belts with lifelines to permit easy rescuemay need to be worn. Refer to Appendix VII and Table VII.1 for a summary of the main work scenariosand the recommendedlevel of personalprotection. 4.7 .3 Protection in event of accidental release scenarios The following guidelinesmay be used to determine personalprotection for escapefrom, or rescuein aleas where HoS is not normaliy present but only after an acciclental release. 200 ppm (< 500 ppm in Where the maximum HrS concentrationin air wiII not exceed. process),where escaperoutes are sholt and the need for rescueis unlikely, it is sufficient to use a monitol QevelA). This might apply to visitors to site, operators carrying out routine checks,or maintenancepelsonnel cioinglight work. eg painting.

18

EP 95-0317Revision0 5 October1995

4 Controland Safe WorkingPractices If a rescuesituation might arise ol escaperoutes are }ong,then a BA set (essentialfor a rescue,Ievel D) or an escapeset (endurancepermitting, level B) shouldbe 'to hand'. This might apply during maintenancework where an injury could occurpreventing escapeor where work is underway several levels from the ground. In areas where the H2S concentrationcould exceed200 ppm (> 500 ppm in process), compressedair full-face mask breathing apparatus with adequateenduranceis necessary. .1

Consideration should be given to how personnel will be alerted when they are not actually breathing from their BA sets. Reliance on a warning from personal or frxed monitors can provide adequatewarning for a distant sourceof H2S when concentrations cannot build up too quickly. For closer sourcesthe sound or sight of a leak will provide much earlier warning. However, the employeeat risk may not be alert to these 'standby' in such warnings if engrossedin work. Hence, the importance of a buddy on HrS work situations. The 'standby'shall be positioned out of the danger area and shall have no work responsibility other than that of obsennrngthe workers within the danger area and giving the alarm.

I I

-t

tI t

I

\

The proximity to the source of a possible release and the time it takes to reach a dangerousH2S concentration are thus important in deciding the state of read.inessfor the donning of a BA set.

I

.t

4.7.4 Protectionin areas subject to sulphate-reducingbacteria(SRB) In all areas where SRB activity takes place, the presenceof H2S shall be consideredas Iikely but not normal and warning notices and area identification shall be applied accordingly.Accessshould be permit controlled. First entry shall always be made by someonewearing BA and carrying a portable gas detector (protection level F). Gas tests should include measurement of flammable gds, toxic gas and oxygen levels. When the HrS concentrationis found to be below 10 ppm and instantaneous release can be discounted, entry is permitted without BA being worn (protection level B or D). Single person accessshould be prohibited. If the alarm of any monitor is set off all staff within the area must don the self-rescueequipment and evacuatethe area without delay. If escapeis particularly time consuming an ('early') alarm setting of 5 ppm may be adopted

4.8

ProceduralControls and Standing lnstructions

Local levels of exposureand the appropriate level of protection of personneland other precautions,should be documentedas standing instructions. For all normal activities these standing instructions should lay down in unambiguousterms: o

which areas are hazardous due to HtS

.

which jobs are/are not coveredby the instruction

.

rvhat precautions are mandator-vin the different situations

.

who may authorise permits for thesejobs.

Detailed guidelines on plepaling proceduresfol HoS are given in Chapter 6.

'1995 EP 95-0317Revision0 5 October

19

i

HSE Manual EP 95-0317Hydrogensulphide(HzS)in operations

4.9

HZS Competence

All personnelwho visit, work or carry out special (emergency) duties in an ar.eawhere HzS is a potentiai hazard neeclto have a levei of com;retencecompatible with the task-s they are expectedto carry out and must be trained..In line with basicprocedures developedas part of HSE managementsystems(seeHSE Manua] Ep 95_0100and Ep 95-0r20),competenceassurancerequires the competenciesto be identifiecl,training to be provided and performanceagainst requirements to be reviewed at regular intervals. only personnel who are trained. and certified to the required level of competenceshould. be allowed entry HrS d.esignated. area. Training record.san6 competence 11 3" certification should be containedin an HSE personaip"r.port or similar document. Accessby personnel to an Hzs area without an H2s entry permit should be prohibited., unless they are under direct control and surveill"-n." of " itoperly authorised an6 trained HrS permit holder who is accountablefor the personnel for the time of exposure.

4.9.1 Competencerequirements Sites with HtS classifiedareas should.have a three ievel competence schemein place.A medical assessmentshould be required for personnel at levels 2 and.B to id.entify any factors which may preclude a person from wearing breathing apparatus. Local reguiations may require more specific med.ical"rr"rr*ents. personnel with known physiological or psychologicalcond.itionsthat impair their normal respiration shall not be assignedto work involving potential exposure to HoS or sulphur dioxide environments if use of breathing equipment o, exposure itself is likely to complicate their respiratory problems. Level 1 - Familiarisation AII staff and visitors to the site should.be aware that the site contains HrS classified areas' and of the hazards and risks of HoS. They should.also be aware of the emergency -should proceduresin the event of a releaseand be informed.and where necessary instructed in the following: o

use of personal monitor and awareness/operationof detection

o .

meaning of and actionsin the event of warning signais (visual and.audible) what to do in caseof HoS release.

.

use ofan escapeset.

systems

Level 2 - Classified area competence AI1 staff who ale required to enter an HoS classified area as part of their normal work should understand and have demonstraied.the ability to respond to the following requirements: o

to recognisethe potential hazard

o

to be fully conversant with and capable of using all types of breathi.rg apparatus @A) as supplied at the location

I

to be fully' conversantwith use of pelsonal and.portable monitoring equipment

o

to understand emergencyrequirements should the presence of H"S be detected. to understand emel'genc)'requilements shoulcla casualtysituation occur.

r

ll

20

EP 95-0317Revision0 5 October1995

4 Controland Safe WorkingPractices

.t

I r \-1 I

I

r

to be able to carry out first-aid for victims of H'S exposure.

Staff with special duties with respect to contlol of HrS or to emergency response during a release will require specialist competence in those aspects of their duties in addition to competence at Level 2. Such staff includes emergency response teams, medics, production site supervisors, drillers and toolpushers, and safety officers.

-'l

I J

to be capable of undertaking their roie in ener.'gencyplans and if necessary take control of contingency and evacuation procedttres

Level 3 - Staff with special duties

l I

o

,

4.g.2 Trainingprogramme The training programme should be commensuratewith the level of competencerequired and may be on an individual basis or as a training course.Where the training cr run externally, or is not specific to the worksite, further training on the procedt detailed.arrangements for the particular worksite should be given. Competenceat Level 1 can normally be achievedas part of the general site introduction. the essentialpoints that must be covereclas a minimum at this le' given above. For staff required to be cornpetent at Levels 2 or 3, a comprehensive tr: prograrnne for designated personnel should contain the following aspects plus any additional local requirernents:

I H2Sintroduction

I J

.

what is HrS

o

characteristics

.

physical properties

o

rrr€asurement of atmospheric .oncentrattons

.

occupational exposure limit for HoS

o

comparison with other gases

CIL\D I

.

sources

.

effects on health

.

effects on environment

.

effects on equipment

.

pyrophoric iron sulphide

.

colour coding

I

ldentification o

area and risk classification

.

safety signs

Safe working practices .

access to worksite

o

p€rsonnel movements

.

wind direction/indication

.

self protection

.

buddy system

.

l'escueprocedure

.

transportation

.

evacuation

.

contingency plans

o

p€rmit-to-work system

EP 95-0317Revision0 5 October1995

21

HSEManualEPg5.O3lTHydrogenSulphide(HzS)inoperations Detectors

servicin g recluirements

fixed

portable

personal

alarm settings

positioning

Iimitations

sensitivitY calibration

ResPiratoryProtectiveequiPment

air hose breathing apparat'us

aratus self- contained breathing app

cascade sYstem

escaPesets

limitations of breathing apparatus

Iocation of breathing apparatus

wearing of breathing aPParatus

mask to face seal checking

working with breathing aPparatus donned

servicing of BA

First aid o

fesuscitation

o

artificial resPiration

emergency response and who are required' to carry out staff above, the to In addition specialist will .u"d to be trained' in their *"d,i.., drillers and HSE officers competencies-

programme 4.g.3 Specific elementsof the training

be adhered to in fotlowing guiderines should the training providing when r".r.l of .otttpetence is achieved': order to ensure the "ppropti"a" . breathing aPParatus(BA) and participate in require all pe'sonnel to wear it should BA of use the in any Training be of a duration sufficient to highlight shourd This ,"rri*. work a simulated. in a search and rescue situation' constraints which could.be d.etrimentar .

detectors The use of Portable a n d o t h e r t y p e s o f H " S d ' e t e c t o r s w h i c h a r e p r o v i d e d o n t h e b-vall participants' instaliation should be practised

.

first aid

with actrve practical sessionson resuscitation' Training in first aid should include gurr. first aicl should'also be explained if this participarion by ail course memberr. of injury' this co,rld be beneficial in the case is not separ.atelytrained for as

4.g.4 ComPetence certification with the 'equired training program*:r.o*mensu'ate on satisfactory compretionof the level' a per*sonalH"S passing a test as appropriateto the on and. competence, of validity Ievel i. *ir." t, Fislr'e 4.2. The maximum "**pI" entry permit .^r, u, issued,.er, coltrses refr-esher year..on expiry of the permit. or r.r.i ^ permit should,be one per-iod. prio' to issttinga in 4.i.: ana 4.7.3shoulclbe attended describecr s*biects the covering tl

22

EP 95-0317Revisron0 5 October1995

,l

4 Controland Safe Working practices new permit. Relaxation to a two-year validity is acceptable in areas of low risk or for those staff involved daily in H,S operations. Figure 4.2

Competencycertificate

Opco

l , l, ' l I \-I

HrS Competency Certificate Level..... This is to certifv that

HrS Competency Certificate

has successfullycompleted training for entry into hydrogen sulphide designated areas Signed Date Expiry Date

4.9.5 Competencereview Proper recordsshould be kept for each person assignedto installations, indicatinp instruction and training were received..Competenceshould be reviewed regularly carrying out drills at the worksite. Experience has demonstrated that drills are extremelv effective.

E P 9 5 - 0 3 1 7R e v i s i o n0 5 O c t o b e r ' 1 9 9 5

23

1I J

5 Recovery

5

RECOVERY

5.1

E m e r g e n c yP l a n n i n g

I-i

5.1.1 Emergencyequipment

-l I

Locations where HrS can be present in the air above the TLV-TWA of 10 ppm s 6ave the following equipment in addition to that provided for normal operation

,j

1I .t

I

|

II .l

spare self-contained BA sets + spare bottles (two additional sets against number being used)

o

spare escape sets (two additional sets against number being used)

o

portable HrS monitor u'ith continuous read out and alarm

r

p€rsonal HrS monitor

r

portable HrS detector suitable for sample aspiration

o

portable notices warning of H'S areas and portable barriers

o

mechanical resuscitation equipment

o

diagram in control room showing location of emergency equipment.

.

1

I

o

-

5.1.2 Procedurefor major HrS release Locations where HrS can be present above the TLV-TWA of 10 ppm should have a written action pian in case of HoS release. It should be based on and include the following information: .

site of H2S risk areas

.

siting of HrS emergency equipment

.

interpretation

.

rescue operations

o

procedures and controls as necessary for people outside facility boundary

.

first aid treatment for HrS poisoning

r

action on hearing Ar'ea HrS Gas A]arm covering, eg:

of the fu'ea HtS Gas Alarm

I

I ; I

"i

separate action for permanent staff and rnsitors/ contractors use of escape respirators assembly points and escape gates roll calI. accounting for visitorsicontractors search and reseue operation. wearing BA and using HrS detection equipment road closures dou'nwind/stanclby boat actions stopping of hot or cold work checks on builcling ventilation informing local conlrnunitl' emergency services r,vhereappropriate

EP 95-0317Revision0 5 October1995

25

a

HSE ManuatEP 95-0317Hydrogensulphide(Hzs)in operations action in case of fires in H"S areas

.

action on hearing other plant gas alal'ms o

methods for iocating a leak source

o

methods of isolating the leak

.

methods of clispersing the leak

o

procedure for all clear and return to work.

for protecting Emergency Response Procedures for HrS reiief should include controls people outside facility boundaries.

5.1.3 RescueProcedures and practised For every site defined as an HrS area, a rescue pian should be developed plocedures and of the as a regular check of the effecii reness of the emergency together with the practice competence of the personnel involved.. The frequency of in the HSB Case' ,..q,rirud performance criteria for the drills should be established part in a rescue Where local medical facilities may be called upon to treat or play a for the procedu'e it shoulcl be confirmecl that personnei are awale of the requirements treatment of HrS Poisoning. part of the person The rescue proced.uresshould be based.on minimum action on the action of the sighting the victim, ie to raise the specific alarm. In other words a single The details of witness should. be sufficient to set the rescue proced.ures in actionto the information medevac, organising med.ical assistance, manpower assistance, point' ,"Jporrribie Supervisor should be left to be organised by a central spot provided they This will allow the witness to take immed.iate rescue action on the are equipped and trained to do so. Rescue procedures should contain the follorving: .

central reporting point

.

r€porting code

.

witness actions

.

r€Porting Point actions.

is permanently The central reporting point should. be situated in a location which alternatives. manned. and alJay. safe. ti ttti. is not possible. procedures shouid indicate points, a This point should be contactabie from the field r.ra dedicated manual call point reporting central d.ed.icatedemergency phone or a dedicated lacl.iochannel. This should be the focal point for cailing in resources, ie medical assistance, experienced manpowel, transport, nr.edevac,etc. be vested with This central reporting point should. have the requisite expertise level and higher'leveisto the authority to call in such l'esoLu'cesrvithout, having to refer of the The reporting code shouicl be sholt ancl precise, it shouid contain the location ' eg HoS caller..his name and a single catchwolcl to ind.icate the nature of the incident, \riCTIM' and possibly the number of pelsons involved' Witness actions: Before an)'resclle attempt tire witness should raise the alarm. is Thereafter. the witness could tr'-va linritecl fesctre attempt provided heishe

26

EP 95-0317Revision0 5 October1995

l l

5 Recovery equipped to do so, ie when he is wearing a BA set the witness could try to isolate the source of the leak.

.t I

-l

Becausepersonstend to rescueinstinctively they shoulcibe trained not to do s not properly equipped.Figure 5.1 beloq' lists first-aid actionsand provides further medical advice on rescueof an H"S vrctim.

I

_t

IF A WITNESS HAS NO BA SET AVAILABLE ATTEMPT TO ENTBR THE RISK AREA

I J I 'J I

'

THE WITNESS SHOULD NOT

The witness should evacuateto a safe area (eg upwrnd of the HoS source)and , sets when possible.Provided one BA set is available and the witness has given the alarm and is familiar with the use of the BA set, the witness should try to carr victim to an HoS-freearea and try to resuscitatehim. A single person attempti rescueneedsto be aware of the risks. If unable to remove the person and a secondBA set were available the witness couid.try to put this set on the vrctim.

-l

Figure 5.1 Medicaladvice

I

First Aid and Medical Advice HrS poisoning is a life threatening condition characterised by loss of consciousness and associated respiratory faiiure. Treatment must therefore be rapid to be effective. Remove the affected person to an HrS free area. If breathing has stopped apply artificial respiration and continue until a mechanicai resuscitator is available to support respiration or until the victim resumes breathing.

I I

Obtain medical attention immediately. If eye contamination is suspected flush the eyes with clean water for up to 10 minutes. Subsequent to the resuscitation procedures described, keep the victim under observation and treat symptomatically as indicated by the patient's condition. The possibility of delayed pulmonary oedema up to 24 honrs after exposure should not be overlooked.. If the victinc is moved to a medical facility, poisoning is supplied to the rnedical staff.

ensure that inforrnation

on HoS

Other points Harmful exposures only occur by inhalation. Intake via other routes is of no medical significance. The use of 4-dimethyl amino phenol as an antidote for the systemic toxic effects of HrS is not recommended. Experience has shown that, following successful resuscitation. recovery will usualiy be rapid and complete without the use of an antidote.

The reporting point should take all the necessaryactions as iaid down in the emelgencyprocedure,thereby relieving the personson site of ail organisational reporting matrers such that thet'can dedicatetheir efforts to rescuingthe endangered hfe.

E P 9 5 - 0 3 1 7R e v i s i o n0 5 O c t o b e r1 9 9 5

27

HSE ManualEP g5-0317Hydrogensurphide(HzS)in

5.2

operations

Firefighting

5.2.1 Hazards Pure HtS is a flammable gas. If burnt in the atmosphere it forms sulphur dioxide (refer to 3'2'3) and water. In concentrationsof 4.3 to 46.0 per cent by volume in the atmosphereit will readily burn upon ignition. In most situations Ho with other saseswhich mav be light oJh"u'oy.pure Hrs;;;h;#t which could be releasedfrom a rich surfinor soruiion is slighiry h;;;; than air.

5.2.2 Precautions In the event of a fire of HrS-containing material, it is usually better to let it burn under control until the sourcehas been isolaied rather than releasl Hrs to the atmosphere. @xposureto the resultant sor, should be avoided.)The;;ffi; equipment should be cooledand wherever possibieattempts mad.e to d.ispersethe sulphur dioxjde product of combustionby water sprays. The decision to allow a fire to continue will d.epend. on the circumstances.If the escape is small in volume and can be isolated easily then extinguishment could be the preferred course of action. A11approaches must be from an upwind direction by personnelwearing a self-contained. breathing apparatus.

5.2.3 Generalprocedures/guidelines The responsibilities for salvage/clean up and the proceduresfor breathing apparatus for firefighters are described in Ep g5-0ssi Fire Control and

Recoverv.

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EP 95-0317Revision0 5 October1995

I 6 Guidelinesfor the Preparationof H2s procedures

l

6

,I _l

Chapter 6 gives somespecificguidanceon the preparation of H"S procedur.esfor typical production, drilling and maintenanceactivities.

I -l I

GUIDELINES FORTHEPREPARATION OF HzS PROCEDURES

Proced.uresfor operationsinvolting HrS shoulclbe written for a specificlocatior conditions prevailing locally. The immediate health effects for people exposedto HrS depend primarily on tht concentrationof the HrS in the air. Precautionsand proceduresshould be basedon

I

r

;ilT#::;'ffi";::::::ffi*:l';""J.:ffi";.,"uu,.bedef

all facilities where HrS may be encountered.While no risks shall be taken it is

]

;m:ilt'Ji" ##Ti?$:'1fffitff;'Te

'

'

equipment than isreasonabrv

h'"3tumil3;i:;:;ff;n?T##ff;::ffi-":ffi"'ffiJlilff

.-

three main elements:

I

: ::;"j;il:ff';:H:i:,":n::." o

6.1

developing standing instructions for all normal activities.

Formulation of Work Procedures

The procedures should be based on the health risk assessment. The following elements related to personnel protection should be covered as a minimum. The requirements need to be defined for: .

work method

.

breathing apparatus

o

detection/monitoring

o

wind indication

.

escape routes

.

rescue plan

.

H:S warning signs.

equipment

Depending on the work scenario and HrS concentrations involved, the wearing of personal monitors, BA sets, escape sets, portable detectors the use of the buddy system, etc should be determined for the different stages of the job. It should be made clear and known who is authorised to conduct the general site introduction. A s1'sten should be set ttp to ensure that all site personnel have a valid HrS certificate. Numbers of staff on site at any given time shouid be kept to a minimum.

EP 95-0317Revision0 5 Octobertgg5

29

HSE Manual EP 95-0312HydrogenSurphide(Hzs)in operations A "r'ork programme should be agreecl and signecl by all parties involved., ie production, maintenance, drilling, contractot's, etc. The programme shoulcl include the for.mulation of special procedures in respect of Hrs hazar.dsdrring,

.

isolation

.

depressurising

.

boxing up

.

spading/Olinding)

o

flushing

o

drying

o

opening up

.

vessel entrv

o

line up

r

pr€ssure testing

o

draining

.

recommissioning

r

puf glng

.

despading/(deblinding)

All procedureswhich cover multifunctional departments should be authorised.by that authority which heads all those d.epartments,ie OperationsManager or Technical Manager or by all parties concerned.

6.2

Drilling and Well Operations

Specific HrS procedures covering Driliing Operations in aleas where HrS is likely to be encountered are documented in EP 95-0210 Driliing (sub-chapter 6.b) and ApI Rp 49 7)' It must be ensured. that such procedures tie-in well @@ef' with the existing local Emergency Contingency plans. Considering the danger and. the consequencesof exposure, when operating in an HrS environment, it is important to take note of the fotlowing key operational precautions which are adequately covered in the above d.ocument and inlne general sections of this manuat: I

o

all personnel on a driJling location where HrS is anticipated. shall have available to them a certified breathing apparatus r t

o

all BoP equipment and tubulars to be used in wells where HrS is expected.to be encountered, must compiy with metallurgical specifications suitable for sour service

'

effective fixed detection systems that activate audible and visual warning alarms must be installed at strategic locations on the well location only personnel trained. to work in an HoS environment may be deployed to work on well locations where HrS is expected.

' ' '

there must be an ag:'eed.HrS 'd.r'i11'plocedurewhich shali be carried out once a week or more frequently until personnel on site are conver.sant with it drills should be monitored. against known and agreed performance criteria.

The effectiveness of any H:S contingency pian can only be assured if all staff involved. in the operations are fully "*tu of the consequences of exposure to HrS. They must be familiar with the right steps to control a hazard.ous ",r".rt *ili " o"tJ"tial release of HrS and to recovel from the hazardou-ssituation should. the release actually occur. Effective training ancl competence assessment ale of vrtal importance to achieve this.

6.3

Production Operations

in Appendix VIII examplesof typical srep-b],-srepprocedules al.egiven (sphere removal,sampling).

30

EP 95-0317RevisionO 5 October1995

!tK--ffiirurun***,.o'l

_t,

:t _t :l

l

6 Guidelinesfor the Preparationof H2s procedures

6.3.1Sampling Whereverpossiblestreamsshould be sampieddownstreamof the HrS removalpr.ocess. Sour stream samplingshould be minimised. Sampling should only be carried out by following approveclproceduresancl uncler a permit to work system. All sampling to be carried out by a minimum of two peopleof which one is always an observer. Samplepoints should be designedto minimise the volume of gas or liquid releasecl during the operations.A.ty releasesshould be remote from the person taking the sample,ensure that the concentrationof HrS in the atmosphereis below 15 ppm (the 15-minuteexposurelimit) and be directed to a restricted area. If this cannot be achieveda BA set should be worn. Samplepoints should be assessedindividually, based on the volume of HrS that coulcl be releasedwhen the sample is taken and the degreeof dispersion".rr-,*irrg worst conditions.In any casea BA set should be worn for sampling sour LPG where the purge is releasedcloseto the sample point. Even with all these precautionsthe operator should always remain upwind of the sample point.

'1 I

i

, I

Samplepoints should be colour-codedand plugged if not in regular use. They should be clearly identified with a notice which aiso specifiesif applicable that a BA set is compulsory. If it is not possible to have a short stub between the line and the sample point then the system should be vented or drained to a closedsystem. Samples should be analysedin a laboratory fume cupboard. To avoid atmospheric pollution, waste gas samples should be bubbied through 20 per cent MEA solution to absorbthe HoS (mono-ethanolamineMEA or di-ethanolamineDEA). AII samplesshould have a label marked 'DAITGERHoS', and should be transported in the back of an open vehicle or boat. In the laboratoriesthe samplesshould.be kept in a fume cupboard,with the extractor fan switched on if there for a short period.ancl outside the laboratory in a secure area if kept for an extended period.. Collectionvesselsmade of material resistant to HoS should be employedwhen sampling sour gas screams.

6.3.2 lsolation Equipment should be isolated in accordancewith 'the minimum mand.atorvisolation requirements'as iaid down in EP 95-0230Design and Engrneering. A doubleblock and bleed consistingof two separatebiock valves with or without a spectacieblind is recommendedfor all systems containing toxic fluids und.erpressure. Isoiation, depressurisationand purging of the main system followed.by iocal isolation is always preferred.This reducesthe number of isolations against high pr.essur-e or toxic material and the amount of valving needed.

EP 95-0317Revision0 5 October1995

31

S u l p h i d e( H z S )i n O p e r a t i o n s H S E M a n u a l E P 9 5 - 0 3 1 7H y d r o g e n

6.3.3 Depressurising Depressurisingof equipmentand processlines should be clonethrough the process vent/relief system to the flare. When this is not possibleand equipment has to be aII sourcesof ignition should be eliminated from the area where clepressurised, flammabie vapours may accumulate. Roacisshouldbe closedoff and signspostedto keep vehiclesand other potential sources of ignition away from the area. Attention should be paid to the wind direction in defining the extent of the possible hazard, in particular with the location of living quarters, workshops, control room or other areas where a number of peopleare continuouslypresent. Concentrationsof HoS vapours should be measuredcontinuously and the rate at which depressurisationtakes place is to be limited to ensure dispersionof the H2S vapours at safe concentrations(ie no risk of personalexposuresin excessof 10 ppm). Such an operation should not be carried out in calm wind conditions.

6.3.4 Flushingand draining Flushing can be done by circulating water or other suitable medium through the process Iines. Equipment can then be drained at the various low points to a safe place. With HrS bearing productsall personnelinvolved in the operation should use BA sets. Warning signs should be placed at various strategic locations around the working site to warn other personnelthat HrS products are being drained. When draining operationstake place through a closeddrain system, check that all drain points on other equipment have been closed and blinded before draining starts. This will ensure that the medium being drained cannot enter previously declared safe equipment or areas where peopleare at workWhen dr.aining operations have to take place into open gutters warning signs should be placedat the drain outlets and along the open gutters and HoS concentrations measured. The drained product should be diluted with large amounts of cold water. Check at various locationsalong the gutter that no HOT work takes place during the draining operations. Always work in teams of at least two men with the secondperson watching from a safe location.

6.3.5 Purging Irrespectiveof whether HOT work is planned on equipment or process lines it is always goodpractice to purge the systemsto be isolated u'ith nitrogen gas or other suitable inert medium. Any of the following methodscan be used: fill the process lines and equipment with watel', aftel which the water is drained and replaced by nitrogen Not recommended for corlosion-sensitive or cryogenic systems.

32

EP 95-0317Revision0 5 October1995

6 Guidelinesfor the Preparationof H2SProcedures r

purge eachsectionof line rvith nitrogen gasuntil the hydrocarbongas is sufficientiy diluted Test to below 10 per cent Lower ExplosiveLimit (LEL) and"ior10 ppm H"S but remember some detectorsrely on cataiytic combustionand do not work in nitrogen atmosphere.

o ,rl J I

I

I I

Venting the system during the purging operations must be done from various vent points in the system to ensure all sections of the system have been sufficiently purged" Repeatedlypressurising the entire system with nitrogen gas should ensure that the dead legs in the system get sufficiently diluted with nitrogen gas.

I

If pyrophoriciron is a possibility further precautionsas describedin 3.3.2shouid be taken.

:

For HOT work to take place on processlines the hydrocarboncontent should be less than 0.1 per cent by volume.

'l l a

pressurisethe entire system with nitrogen gas and vent to flare or atmospherea number of times (test as above).

Specialcare should be exercisedwhen declaring a system safe for HOT work when lower explosivelimit levels are being determined d.uring the relative cool hours of the night or morning. Processlines always contain minute amounts of hydrocarbon productswhich will releaseflammable vapours when heated up due to the ambient temperature rise or direct sun radiation. For further referencesee SSHC Guideline Gas Freeing and Cleaning of Oil Storage Tanks @ef. 9) and EP 95-0270 GeneralWorkplacePractices.

6.3.6 Vesselentry For full procedural guidelines on vessel or tank entry see EP 95-0270 General WorkplacePracticesand HSC Guideiinesfor Entry into Confined Spaces1992 (Ref.8). Further to the above guidelines the following precautions should also be taken: .

the first opening of any vessel should always be carried out by persons wearing full air supplied breathing apparatus with at least one person watching from a safe distance, ready to raise the alarm and don BA in the event of difficulty Once the first manhole is removed a check should be made of the internals for debris and H"S.

o

if debris is present then steps shouid be taken to keep air from it, usually by damping down Air supplied breathing apparatus should be worn until such time as the HoS is below 10 ppm and all of the debris is removed.Care should be exercisedas the HtS ppm level may rise whilst debris removal is taking place.

.

the initial entry into a confinedspaceshould aiways be made by a pelson attached by a safety line to the outside and wearing fuli air line supplied breathing apparatus

o

personalHrS detectorsshoulclbe worn at all times In the event of alarm the causeshould be identified and the level of H"S determined.Suitable action shouid then be taken to reducethe level below 10 ppm beforework resumes.

EP 95-0317Revision0 5 October1995

33

H S E M a n u a l E P 9 5 - 0 3 1 7H y d r o g e nS u l p h i d e( H z S )i n O p e r a t i o n s

6.4

MaintenanceOperations

The following are essentialelementswhen planning and executingmaintenancework in an HrS environment.A competentsupervisor shouid be placed in charge of the whole operation.He will liaise closelywith the Operating, Engineering or Maintenance department at all times. Detailed discussionsbetweendepartments are essential in the early planning stagesof the work. Such discussionsshould include: o

a clear definition of action parties and areas of responsibility

o

an appreciationof any operational constraints which can affect the plan eg Iive processlines or equipment in operation adjacentto the actual worksite, time constraints, the availability of flushing lines/equipment to a safe standard.

.

details of the product carried in the lines or equipment to be decommissioned eg HoS,pyrophoriciron, toxic hazards.

o

details of any other work taking place or planned in the vicinity, which might affect or be affectedby the planned work schedule.

Oncethe basic planning has been established,the supervisorshould carry out a site inspection with the personnel involved. This inspection should include: o

restrictions and any a survey of the surrounding area to establish access/egress sourcesofhazards

o

a check of any work taking place in the vicinity of the equipment being decommissioned

o

a check on the location of existing fire equipment and respiratory protection equipment and an assessmentof any additional equipment that may be required.

The working team assignedto the job should then be properiy informed as to the specificcircumstancesand requirements and be instructed and trained in the use of the necessaryequipment.

34

EP 95-0317Revision0 5 October1995

AppendixI Formationof H2Sby SulphateReducingBacteria(SRB)

I APPENDIX BACTERIA OF HZSBY SULPHATEREDUGING FORMATION

(sRB)

,

When the oxygen consumed by bacteria or by chemical interactions is greater than the oxygen input into the water, a iowering of the dissolved oxygen content will occur. In

,l"ili"l:'JJ:ii;l11;:litTtr;:i;r"'"TH?i::: :iffi::,i'*TJlffi their metabolicprocessesleading to the formation of HrS and other bacterial products.

j

:H:ffi::'#:1ff"::::l,T.""uitions

wi'onry becreate, rorsRB

following nutrients are present in the water:

. i

.-

.

a carbon enerry source,ie organicmatter such as oil or lower fatty acids (abundant in formation water)

.

sulphate (SOa,abund.antin seawater).

The temperature is another important factor which regulates SRB activity: growth rates are optimal within a temperature range of 20 to 30"C. At lower temperatu growth is reduced but is still evident at 5 to 10"C. Hazards associatedwith SRB activity are: Fornaation of HzS HzS is sparingly solublein water and will, therefore, move into the atmosphere.This could lead to lethal concentrationsof HoS directly abovethe water column and, consequently,to unsafe situations particularly in areas which have restricted ventilation. Forr''ation

of acid compounds

Anaerobic growth of bacteria in water results both in the production of HrS and acidic compounds.A drop in pH often occurs(a lowering of pH from 8.2 to 6.0 in a period of 15 hours is not unusual). The acid conditions created can contribute greatly to the rate of corrosionof metals and the disintegration of any concretethat comesinto contactwith the water.

1.1 Monitoringof SRB Activity The early onset of SRB activrty can be detected by measuring the HoS content of water from the suspect source. This is normaliy done in a iaboratory but a simpie qualitative test kit using lead acetate paper is available from HACH for use in the field.

1.2 ControlMethodsfor LimitingSRB Activity Several methods have been used to control SRB activity. One approach to reducing the activitl- of SRBs is by the use of biocides, chemicals rvhich porson the bacteria.

E P 9 5 - 0 3 1 7R e v i s i o n0 5 O c t o b e r1 9 9 5

35

HSE Manual EP 95-0317HydrogenSulphide(HzS)in Operations The effectiveness of conventional biocides fol tire control of SRB activity is reduced in many situations, due tci: .

the difficultf in achieving a homogeneous mix between the biocide and the stagnant water'

.

the environmental/ecological constraints As the use of biocides could lead to the discharge of unacceptably large volumes of toxic materials

.

the generally high cost of biocides

.

SRBs building up a resistance to individual biocides.

To overcome the resistance build up, dosing of alternative chemicals at intervals could be tried. For example a weekly switch between two or more compounds or shock doses every few weeks can be used. Chlorination is also a possibility but there are doubts about its suitability readily dissipates in stagnant water conditions.

as chlorine

A preferred alternative to the use of biocides or chlorine for controlling the activity of SRBs is aeration of the water. This method is particularly attractive in the offshore storage and separation of oil and water. Aeration of water volume in storage cells can be achieved by introducing (compressed) air into the stagnant water, thereby severely iimiting the growth of the anaerobic bacteria. A second method is by continuously changing the water thereby maintaining an appreciable level of dissolved oxygen in the water. If aeration of the water i's applied corrosion rates will probably be higher and this will have to be taken into account during the design stage (material selection) or in operation (corrosion inhibition). The use of germicidal ultraviolet light in the treatment of the water may be another option, but may not be fully effective if solid particles ale present. If SRBs are suspected or confirmed, a testing programme should be set up at the earliest practicable opportunity to evaluate the best control method.

1.3 Safetyin PotentialSRB Activity Areas Safety precautions must be taken in all aleas where SRB activity takes place and where the build .,p in H"S concentrations (above TLV 10 ppm) couid be potentially harmful to personnel. The same precautions should be taken as for normal H"S releases.

36

EP 95-0317Revisron0 5 October1995

".e

..:Jnl.ria;,&.ba

r..--....

Appendixll PhysicalPropertiesand Physiological Effectsof H2S

APPENDIX II PHYSICAL PROPERTIES AND PHYSIOLOGICAL EFFECTS oF HzS ll.1

PhysicalProperties

Table ll.1

'\-

Physicalpropertiesof HrS

Property

V al u e

Auto-ignition temperature

260"C

Boilingpoint

-60.2'C

Meltingpoint

-82.9"C

Criticaldensity

0.349g/ml

Criticalpressure

9 0 . 2 3b a r a b s .

Criticaltemperature

100.4'c

Density:gas 0'C 1 atm.

1.5392gll

Density:liquidat boilingpoint

0 . 9 9 3g / m l

Flammablelimitsin air

4.3 to 46% (by vol)

Freezingpointat 1 atm.

-85.5'C

Molecular weight

34.08

Solubility in water0"C, 1 atm.

0.6729/100ml water

Specificgravity15'C, 1 atm. (air= 1 )

1. 18 9 5

Vapourpressure-20"C

1 8 . 1b a ra b s .

ll.2 Characteristics

l" IH#*i:::rab1e

byitscharacteristic rotten.egg odour At

(above100ppm),H:S rapidly par:aiyses higherconcentrations the senseof smell. ODOIJRS}L{LL NOT THEREFOREBE USED AS A WARMNG MEASTIRE o

normaUy present as a gas and not as a liquid

.

soluble in both water and hydrocarbon liquids. Pools of water or sludge at the bottom of a tank may thus contain concentrations of H"S and if ag:tated or heated will release the gas pure HrS is heavier than air and can collect in los' iying areas. especialiy pits and sumps rvhich are closed-in and have poor ventilation. Horvever'. potentiall-"* fatal concentrations of H,,S (ie 500 to 1.000 ppm) in ail do not act like a heavrerthan-air gas

EP 95-0317 Revision 0 5 October

'1995

37

i

HSE Manual EP 95-0317HydrogenSulphide(HzS)in Operations .

is available it can burn when mixed with air and when an ignitiou sottrcer

.

it burns with a biue flame anclgives off sulphur dioxide (SOu),which aiso provides a health hazard (see3.2.3)

.

it can form pyrophoric iron sulphide on the internal surfacesof carbon steel equipment containingHrS. Pyrophoriciron sulphide can auto-ignite when coming into contact with air.

.

it is corrosive in the presenceof water

.

it causescracking and embrittlernent of metals under certain conditionsbut steelsof the correctquality which are resistant to these forms of attack can be used.

ll.3

PhysiologicalEffects

Table ll.2

effectof H2S Physiological

Concentrationin air 1 ppm

Effect Odourof rotteneggs can be clearlydetected

1 0p p m

Unpleasantodour.Possibleeye irritation.ACGIH recommendedThresholdLimit ValueTLV - TWA see 11.4.

15ppm

A C GIHT L V S TE Laveraqedover 15 mi nutessee 11.4.

20 ppm

Burningsensationin eyes and irritationof the respiratorytract afterone houror moreexposure.

50 ppm

Lossof senseof smellafter about 15 or more minutesexposure.Exposureover one hour may leadto headache,dizziness,and/orstaggering.Pulmonary oedemareportedfollowingextendedexposureto greaterthan 50 ppm. Exposure at 50 ppm or greatercan cause seriouseye irritationor damage.

1 0 0p p m

Coughing,eye irritation,loss of sense of smellafter 3 to 15 minutes.Altered pain in eyes,and drowsinessafter 15 to 20 minutes,followedby respiration, throatirritationafter one hour.Prolongedexposureresultsin a gradualincrease in the severityof these symptoms.

200 ppm

The senseof smellwill be lost rapidly,and it will irritatethe eyes and throat. Prolongedexposure(>20 to 30 minutes)may cause irreversiblepulmonary of fl ui di n the l ungs. o e d e m a ,i e accumul ati on

300ppm

Markedconjunctivitis and respiratorytract irritation.Concentration considered to l i fe or heal th. i mme d i a te ldangerous y

500 ppm

after shortexposure,breathingwill stop if not treatedquickly. Unconsciousness Dizziness,loss of sense of reasoningand balance.Victimsneed promptartificial (C P R )techni ques. resusci tati on v e n ti l a ti oann d /or cardi opul monary

700ppm

quickly.Breathingwill stop and deathwill resultif not rescued Unconscious promptly.Artificialventilationandiorcardiopulmonary (CPR)is resuscitation n e e d e di mmedi atel v.

> 1 0 0 0p p m

U n c o n s c i o usness at once.P ermanentbrai ndamageor deathmay resul t. Rescuepromptlyand applyartificialventilationand/orcardiopulmonary (C P R ). re s u s c i ta ti on

For fulthel details seeAPI RP 55 [Ref. 10).

38

EP 95-0317Revision0 5 October1995

.r?L"'

i

uiiliii*;!;;.*r*-.-,"

I

Effectsof H2S Appendixll PhysicalPropertiesand Physiological

ll.4 OccupationalExposureLimits The occupationalexposurelimits referred to below are thosepubiishedby ACGIH -1994 anclthis document is updated and published annually. Threshold Limit Values (TLVs) are guidelines used when referring to the airborne concentrationsof substances.They are called: Threshold Limit Value - Tirne Weighted Averages (TLV-TWA) The time-weighted averageconcentrationfor a nolmal eight-houl workday and a 40hour workweek, to which nearly all workers may be repeatedlyexposed,day after day, without adverse effect. Threshold Li-'it

Value - Short Terrn Exposure Lirnit (TLV-STEL)

The concentration to which workers can be exposedcontinuousiyfor a short peliod of time'r'ithout suffering from 1) irritation, 2) chronic or irreversible tissue damage,or 3) narcosisof sufficient degleeto increasethe likelihood of accidentalinjury, impair selfrescueor materially reduce work efficiency, and provided that the daily TLV-TWA is not exceeded.It is not a separateindependentexposurelimit, rather it supplementsthe time-weighted average (TWA) limit where there are recognisedacute effects from a substancewhose toxic effectsare primarily of a chronic nature. STELs are recommendedonly where toxic effectshave been reported from high sholt-term exposuresin either humans or animals. A STEL is defi.nedas a 15-minute time-weighted averageexposulewhich should not be exceededat any time during a workday even if the eight-hour time-weightedaverageis within the TLV. Exposures at the STEL should not be longer than 15 minutes and should not be repeated more than four times per day. There should be at least 60 minutes between successiveexposuresat the STEL. The current TLV-TWA is 10 pprn (L4 rnglrn3) and the TLV-STEL is L5 pprn (21 6g/mg) for L5 rninutes. These lirnits are based largely on the irritant properties of HrS. The graph overleaf Figure II.l gives an indication of the acute effectsof exposureto HrS. Exposure should be kept strictiy to levels belorvthese limits. Be aware that rvhere the sourceis rich in HoS, gas or liquid, the transition from lou' to very high exposure may be instantaneous.

E P 9 5 - 0 3 1 7R e v t s t o n0 5 O c t o b e r1 9 9 5

39

i

HSE Manual EP 95-0317HydrogenSulphide(HzS)in Operations F igur e l l .1

Ac u te e ffe c ts o f e x p o sure to H 2S

I

minor irritation o o

lt nv

c,

' '- ----T- I

; I

I I

I

I

II I I

I

l

i t

l

-

10


H2S Concentration ppm (volume)

" P o t e n t i a l l yl e t h a l f o r t h e m o s t v u l n e r a b l e p a r t o f t h e p o p u l a t t o n( 5 % ) R e m r n d e r : l h e s h a d e d a r e a s a r e o n l y a p p r o x r m a t i o n sa n d t h e g r a p h s h o u l d b e u s e d a s a g e n e r a l g u i d e h n eo n l y

40

EP 95-0317Revision0 5 October1995

*L

t

;;&b*b;.;..

.*q!&.-.

:.

I I

i

Appendixlll H2SCorrosion

III APPENDIX HrSCORROSION

il

I

lll.1 Types of Corrosion Damage When d.issolvedin water H"S forms a weak acid which is corrosiveto steel. In the reactionbetweensteel and H"S: Fe + HzS -) FeS + 2H atoms. Normally these atoms react to iron sulphide is formed, together with h5'clrogen form hydrogen gas: 2H)H2 but this reaction is sloweddown in the presenceof HoS, and the resulting hydrogen atoms migrate into the metal. Two types of corrosiondamageoccur.These are loss of wall thickness and hydrogen damage.

lll.1.1Loss of wall thickness a

Generalcorrosion The formation of iron sulphide, a corrosionproduct under the right conditionscan slow down further corrosion.If iron sulphide scalesare adherent, tight and dense,the generalcorrosionrate is expectedto be low. Pitting corrosion

\-.

If the iron sulphide scales break dcwn locally the exposed fresh metal areas may actively corrode leading to a severe form of corrosion pitting. High concentrations o chloride ions, elemental sulphur, settled solids and oxygen are among the known cz of iron sulphide scale breakdown. Carbon dioxide can also severely increase both general and pitting corrosion.

lll.1.2Hydrogendamage Sulphidestress cracking (SSC) The hydrogenatoms embrittle the steel. At locationswith high stress and a susceptible microstructure this leads to cracking of the steel and sudden failure. Hydrogeninduced cracking(HlC) The hvdrogen atoms diffuse to inclusions in the steel, mostly MnS, and AloO, where they combineto form gaseous(molecular)hydrogen.The resulting pressule results in the formation of cracks.mainly palallcl to the steel'swall. One or more surfacesof the 'blister' formation. HIC can occur in the absenceof applied steel may bulge outwards in stress.

EP 95-0317Revision0 5 October1995

41

HSE Manual EP g5-0317 HydrogenSurphide(HzS) in operations stress-orientatedhydrogeninduced cracking (SoHtc) The presenceof a t'ensiiestressin the u'all oi'a vesselor'lripehnemaclefi.omsusceptible steei may result in throughrvalltinking of incliviciuai HIC cr.acksthr.oughan embrittlement mechanismtermed soHiC. The incliviclualcr.aclisofren appear.asa stackedarray through the vesseror.pipelinewail. Corrosion resistant alloys stainless steels,nickel-baseclalloys ancl titanium alloys are used to a limited extent in production operations'Thesematerials are also susceptibleto weight loss corrosionin the forms of general and localisedcorrosion( pitting ancicrevicecorrosion)as well as stress corrosioncracking (scc) anclhycrrogeoembrittlement.

lll.2 Protection Protection of the equipment should be consiciered. cluring engineering design and from the outset of production operations ancl not left until corrosion is d.etected.. Various design and operational steps can be unciertaken to limit (or at best eliminate) sulphide corrosion and the ensuing hydrogen embrittlement, namely: Pitting corrosion Traces of air should' be kept out, d.amage of sulphide layer avoided. Inhibition with oiVinhibitor system when corrosion monitoring shows the corrosion rate to be unacceptably high' The use of so-called HrS ,u-ri.trrrt steel refers to resistance to cracking (see III'4) and has nothing to do with resistance to pitting corrosion. some stainless steels and, at high tempei'atures, some nickel alloys can be used.to hand1e very corrosive sour conditions. copper base alloys may und.ergo accelerated.weight loss corrosion in soul oilfield environment, particular.ly *h"ru oxygen is present. SSC Plant should be constructed. fi'om steel which complies with NACE guid.eline MR-0 1-75 (Ref' 11)' Main requirement is control of the steei.s hard.ness to 22Rockwell C max. There is no established protection for a piant which d.oesnot comply with NACE and which handles sour streams. such a situation rvould constitute a clefinite safety hazard.

Htc All .olled steel p'oducts lihe p'esstr'e 'essels and seam-rveld.ed. pipe sho'ld comply with DEP 31'40'20'31-Gen @ef. 12), rvhich limits the suiphur concentration in the steel to 0'003 per cent and requires the steel to pass a qualificatron test. Forg:ngs ancl seamless pipe are normally less susceptible to III-C than eq.ripment made from plate, however., there have been occurrences of HIC in seamless pipl within the gr.oup.For seamless linepipe it is normal to specifi' IIIC testing. Fo'. seamiess piping in p'ocess plant, where monitoring of HIc damage is possibie. it is normai to specif-v" Lu*iroum sulphur content of 0.01 rvt pel cent in the steel. In contr"astwith SSC, HIC can be monito'ecl with trlr,'.asonicinspection techniques because it develops mol.e slowi1'. horve'er'. suclclen failure fi.om HIC has occurr.ed., Exposure of eqtripment to conciitions ri-hich could possibll' cause HIC is oniy allowed in exceptional cases' and onlv rvhen stirtable monitoring ancl inspection progl.ammes are implemented.

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Appendixlll H2SCorrosion \\Tren conditions permit. an internal organic coating ls an acceptable defence (Ibr I not for SSC). Inhibitors ale not accepted as an established defence againstHIC. In general. drying is the best defence agarnst all risks stated above. Removal of the H solve materials problems by chemical scavenging or absorption is not a practical method.

lll.3 Definitionof Sour Serice

'

\-

The definition of sour service(of equipment) is historically linked to the amount of which can causeSSC.The NACE guidelineMR-0I-75 states that SSC is considerec possiblewhen the partial H"S gas pressure (= mol% x total pressure)exceeds0.05 (0.0034bar). Liquids in equilibrium with such gas are also consideredto be sour. Systemswith a total pressule less than 65 psi for gas systems or 265 psi for oil sys are thereforeconsideredoutside the scopeof this document.For tubing and casing, more susceptiblegradesof steel are allowed for temperatures above80"C. For HIC there is no international standard. The present SIPM policy is that HiC cr occurin water-containingliquids in equilibrium with partial HrS gas plessures exceeding0.05 psi, as above,but without any exemptionsfor lower pressuresor hig temperature becauseof lack of evidenceto this effect.

lll.4 Common Pitfallswith Materials in Sour Service The name'HoS-resistant steel' refers to resistance to sulphicle stress cracking (SSC) only and the use of such steel gives no protection at all against pitting corrosion. The NACE guideline does not address the risk of HIC and compliance with MR-0I-75 gives no protection against HIC. MR-O7-75 addresses SSC only. It gives no guidance on synergistic chloride ion/sulphide ion stress corrosion cracking of stainless steels and some nickel-based alloys. 'magic There are no bullets' (why can't we add an inhibitor'?) to save equipment in sour' service which was not designed for it. Monitoring and inspection plogrammes cannot reduce the risk of SSC in equipment which does not comply with NACE. Cracking can develop too fast for this. I

'\-

References: NACE Standard MR-01-75 Gef. 11) DEP 31.40.20.31-GenLine Pipe fol use in oil and gas operations under sour conditions. (Ref. 12) P i p i n g C l a s s e sD E P 3 1 . 3 8 . 0 1 . 1 5 - G e n( R e f . 1 3 )

lll.5 Maintenance SparePartsSour ServiceEquipment Use of spare palts and replacement mateliais must be subiect Loextra plecautions. A control system must be in folce. ensur'rng that spare palts and materjals for repail and maintenance of sour system al'e n-rantifacttrredto the NACE specified materials specification. T h i s o f t e n r e q u i r e s a d e d i c a t e c lm a t e l i a l s i n v e n t o r y c o n t l o l s v s t e m . N , i a i n t c n a n c ea n c l materiais supply,'staff must be rnaciefulh- awal'e of the special r:eqtrilements fol sour' selr..iceequipment.

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AppendixlV Pyrophoric lron Sulphide

IV APPENDIX R O NS U L P H I D E PYROPHORIC lV.1 Formation

'

Iron .sulphide is formed when st,eelcomes into contact,with HrS in the absence of oxygen. When formed as a corrosion product in this way it is usualiy very finely divrder and oxidises rapidly on exposure to the oxygen in air. This generates a lot of heat and pyrophoric iron sulphide can auto-ignite. This can cause an explosion or fire if hydrocarbons together with air are present. The chemical reactions are complex but ca be simplified to (chemically unbalancecl): FeO+HrS)Fe*S*+H2O FeS + Oz J

\--

Fe*O* + SO2 + Heat

Even if hydrocarbons are not present, the exothermic oxidation of pyrophoric iron sulphicle can generate enough heat to clamage the equipment. Pyrophoric iron sulphide can form even at vely low H"S concentrations (<0.1 ppm) as long as the partial pressure of HoS exceeds the partial pressure of oxygen in the environment. The amounts formed will of course be reduced if the internal surfaces are cleaned regularly and kept relatively free of iron oxide by remoting the water produced during the reaction. Iron sulphides formed at high temperatures are more reactive (oxidatively) than iron sulphides formed at low temperatures.

lV.2 Handling Pyrophoric lron Sulphide !V.2.1Openingup to atmosphere

\*

Great care should be taken when opening up equipment to the atmosphere. Oxygen wi react w-ith the pyrophoric debris in an envilonment which is not yet hydrocarbon-free and thereby cause an explosion and file but even when hydrocarbons are removed the pyrophoric debris can stalt burning spontaneousiy. One should rernernber that in pyrophoric matter, combustible material and ignition source are combined and will react in the plesence of oxygen. Removal of hydrocarbons by. eg nitrogen pulgrng of gas systems rvili remove the dange of explosion but not necessarily the dangel of file. Dampening down n'ith water will retard the reaction and allow safe removal of the debris. This mai'be the only practical method in large installations. eg storage tanks. I certain applications however the introduction of water is not permissible, in sour systems from a corrosion point of view. and in cryogenic sy'stems due to the risk of process freezing. The best way to deactivate the clepositsrs to follow the nitlogen purge with a mixtnle c 5 per cent oxygen in nitlogen rvhich allorvs controlled oxiclation.

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i

HSE Manual EP 95-0317HydrogenSulphide(HzS)in operations

l V. 2 . 2 R e m o v al / c o n t ai n m e n t E a c h c a s es h o u l d b e j u d g e d o n i t s o r v n r n e r i t s . b u t m o s t i m l r o l t a p t i s t h a t n g i g n i t i o n takes piace. Although the intt'oduction of watel fol clampening clown may be prohibitect in view of possible corrosion. this may stiii be a feasible option in certain par.ts of a plant. The trse of water may be prohibited in a launcher because of its inclination but it is possible to dampen down a receiver (whele after all any clebris is received) because of its declination. Special attention should in this case be paid to wetting of collection trays. Vent and flares in sour service should be pulged at all times cluring normal operations to prevent introduction of oxygen and special measures shotrld be taken wherever this purge is interrupted ol discontinued. When a plant is shutdown for a longer period the vent ancl flare lines shoulcl be purged. and blinded off. Vent and flale iines rvhich had been nitrogen pulged ancl spaded off have been observed to glow cherry red after a spoot had been removed. for modifications. Special care should be taken while opening up fixed or floating loof oil storage tanks. Mixing of siudge with the crude oil and flushing q'ith water will at least avoid. a hydrocalbon air mixtur.e rvith the pyrophoric debris. For equipment temporarily out of operation (centrifugal compressor) a continuous pur.ge under slight overyressure may. grve adequate protection.

lV.2.3Transportation,storageand disposal it is important that any pyrophoric debris remains wet, preferably submerged. in water, throughout the period of storage and tlansportation fi'om the worksite to the designated. safe area for its disposal. Transportation should be in a watertight metal container. The container used.for tlansporting the pyrophoric debris should be cleariy identified ancl must never be transported together with flammabie materials. It is also good practice to pack equipment, such as filter elements rvhich may contain pyropholic clebris in plastic bags to keep oxygen away. One way of disposal is to durnp the pyrophoric debris in a dedicated safe location exposing it to the atmosphere and oxid.ising it. Note: One of the products of this oxidation is SOo which also pr.ovides a health hazar.d.. refer to 3.2.3.

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AppendixV H2SDispersion

A P P E N D I XV H Z SD I S P E R S I O N 'TRC Table V.1 gives the results of clispersioncaictriations performed using the Dispersion'model within the FRED Version ?.1suite of pt'ograms. The TRC Dispersion moclelis in fact an integrated suite of models. The program takes the initial release conditions ancl,if necessary, atrtomatically makes the transitron fi'om jet dispersion to Gaussian (btroyzrnt)ol hear,l gas dispersion. Table V.1 indicates the clistancesfi'om source to H,S concentlations of 200 ppm and 10 ppm for leaks from three hoie sizes and two containment pressul'es.other assumptions are: 1.

Release is continuous, holizontal and in the clirection of the wind.

2.

Reiease height is 3m

3.

Wind speed is 3m/s (at 10m stanclalcl meteolological herght)

4.

Neutral conditions

5.

Surface roughness is 0.03m (fair'ly level grass plains or deselt)

6.

70 per cent humiciity. ambient temperatule 15"C

7.

Parent medium is methane. 99 per cent methane. 1 per cent HrS

8.

Sample time of 10 min FRED calculates using 10 min, the results are simiiar fol a 15-minute sample time used in II.4, Occupationai Exposure Limits)

These conditions have been albitlariiy chosen. The table is an exarnple only, each specific case must be modelled separately. The results may then be used to assess the feasibility of HrS in concentrations of 10 ppm, 200 ppm, etc reaching aleas of conceln beyond the ciassified 'HoS Risk Alea'. Table V.1

Examplesof 1 per cent HrS in methane,dispersion distances Pressure 5 barg

Pressure 50 barq

H o l e d i a m e t e r( m m )

Dis t anc e( m e tre s )rn dir ec t ionof j e t to dis oer s et o .

200ppmH2S

1' O nrn " n YF'

F - ^l Q

A 6 A

JOU

I

I

' A

ZIU

Note Basedon one per cent H.S in methane T h i s t a b l e i s a n e x a m p l e o n l y . e a c h s p e c i f i cc a s e m u s t b e m o d e l l e ds e p a r a t e l v

. r. l i s t , o f s r . r i r s l q L i e nvte r s i o n s o f T h e s e c a l c t t l a t l o n si r a v e l r e e n l ' r i n o n I l n E l ) r , e ' r ' s i c )" r. 1 I r R , E D .o t ' o t h e t ' n r o c 1 , ' i sr.l r a v g € ' l r c l a t ec l i f l ' c l e n tr e r s t r l t sl.r o w e \ - e rt h e o l c i e l ' o f m a g n r . t u c i e shotrldbe similar'.

Rr)vrsror

17

&.. ^

U.i..---AppendixVl H2SDetection

VI APPENDIX HrS DETECTION systems vl.1 FixedDetection/Monitoring V|.1.1General of sensors permanently installed at fixed Hrs detection is achieved by havrng a system to the atmosphere or accumulate. Portable locations where HrS is most likely io exit is They mal.be used in locations where it sensors are used for alerting the ind.ivrdual. facilities back-up can also provicle the required not practical to install fixed"sensors, and in the event of fixed system failure' of possible leak sources in an HoS-containing section It is very d.ifficutt to define all the that in practice to position Hrs detectors such a process, and therefore it is not possibie the include .o.,r.". Further complications they will detect leaks from each iossibie of the speed's,plant geometry and the density range of possible wind. direction, and outdoor' provrde aclequate reliability, especially in an rereased.carrier gas. Moreover, to testing' calibration and maintenance' situation, such systems require r"gt'lar ground level systems shoulcl be instalied above sensors for the detection and monitoring -containing pipeline such as Hos (ie a minimum of 1.2 m) except in special situations and HrS ulg loi necessariJy:heavier than air trenches. Hazard.ous concenti'atior* of They concentration' ihe Hrs b'eathing zone sensor.sat ground. rever may not incricate etc' can also be easily contaminated by splashing, flow it may be practical to install pressure or In some cases, for example a pipeline' due to a rupture. trips to give warning of a serious release detection systems make an important Despite the foregoing limitations, HrS an Hos-containing plant' DEP 32'80'10'10 contribution to the safety measu'es on (Refl 14) provides a methodology to select the (Instrumentation protective Functions) are trvo appl'oaches which are normally appr.opr.iatelevel of safeguarcling- There 10)' "ppft"a. Refer to API Guide RP 55 G'ef'

source v1.1.2Sensorsof leak detectionfrom single from a single source where the HoS concentration A sensor is installed to detect,ieakage trign probabihc.v of a leak' It is generaliy in the fluid is high and./or there is a relatively design measure to minimise the appired on equipment for which an alternative to d.irect it to a safe location, is not readily probablity and/or quantity of a rerease, o-rbe wired into a shutdown logic' availabie. A detection system may also

V1.1.3H2Sarea monitoringsystems

into plant a.eas from any source and Detectors ar.einstalied to detect H"s d.ispersecl in N'lonitoring systems a'e generaliy applied thus also covers the less likely .or,i.".. u,here the installation of individual detectors enclosed process builcl.ingsand in areas jr.rstifiecl.eg sightgiasses. control valves, d'ain for each potentiar sour.cecannot be points. etc.

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i

HSE Manual EP 95-0317HydrogenSulphide(HzS)in Operations Upon cietectionof H2S at a concentration of 10 ppm or grczrler'.thc sJ/sLemsshould sound a unique alarm and register a visrrzrlalarm in the main conLlc.rl room. The monitoling system should also be capable of displaying an alarm fi'om any of the inclividual sensor'locations and indicate the alea affected. Consicleration should aiso be given to providrng both an audio and visual alalm in the building or' location wher.e the HrS is detected. Guidance on the location of sensors in open areas is provided in EP 950230 Design and Engineering. For further infolmation on design and selection of fixecl HrS detection s-r'stemsfor driliing locations refel to EP 95-0210 Drilling.

Vl.2 PersonalH2SMonitors In selecting a personal HoS monitor the foliowing points should be considerecl: Intrinsic safety The equipment must be certified safe to use in potentialty flammable atmospheres, including hydrogen/air mixtules. where appropriate. Operability The equipment should be light, easy to handle and straightforward to operate by one pelson. Robust construction should ensure continuous operabiiity and intrinsic safety. Measuring range This should cover 0 to 50 ppm and instruments are availabie with a continuous readout. Alarm level This is normally preset by the manufacturer at either one or two different levels (warning and evacuation levels). It is recommendecl that units are purchased which alarm at 10 ppm. Alarm signal Monitors g:vrng an audible aiarm. \trhele high noise levels may mask the aud.ible signal an extension ear plug is recommendecl. Accuracy The accuracy of H,S personal monitor.'-"i-qtypicaliy +l- LS per. cent. Humidity The monitor shor,rldbe capable of functioning within the limits of its accuracy in humidities ranging from 10 to g5 pel cent. It should function at gleater than g5 per. cent humiclity if watel is kept off the sensol heacl ancl rviil tenci to lesilond at lower H"S levels. ie the 10 ppm alarm could be activateci at lorvel ievel-q.The unit shoulcl r..i.,rr, ,o no|mal readings fot'H:'-q when retttlneci to lorver'humiditl,' conditiops. The const].ncrion of the housing shoulci not allorv slrlash rvater. fol examl-rleririn rvater. to penetr.ate the sensol'. Tem peratu re Tire monitol shortld normally be calrable of'f uncttonnlg o\/el'a I'ange of 0 ro 50'C. \\:6er.e the eqtripment i-" r'eqtrit'edfor ttse in sub-zelo tempelatules. the mantifacttrr.er./sr.rppliel

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AppendixVl H2SDetection should be contacted because trnits porvered by special lithium batteries are available 50"C. It sbould be noted that lorn'temperatut'es which function ovel' a range of -40'C t,r.r seriously impede the speed of response. The effects of temperatttre should be confirmecl with the equipment manufactuler.

Batterycheck The monitor should be fitted rvith a check device to indicate the power level in the battery. The battery should be capable of operating fol a minimum of 10h. Alarm response time The monitor should be capable of aialming at the 10 ppm level within 15 secondsof the sensor being exposed to that levei and within 3 secondsat the 50 ppm level. Interfering compounds Substances such as hydrocarbons, mercaptans and SOo shor.ridnot advelsely influence the detector system within the range of 0 to 50 ppm of H"S.

Monitor calibrationand functionalcapability A reliable field calibration kit and function test capability shouid be provided by the equipment manufacturer. This should be used to verify the monitor at least onceper day or shift. Fail-safefeatures Care should be used when selectingspecificHoS monitoring units to determine whether' the system is equipped with internal fail-safe checksthat will sound the alarm or trigger a warning light if there is a defectin the monitor. Service The availability of service and spare parts should be of plimary considerationwhen selectinga palticular system. Product information on commerciall5'available detectionand monitoring equipment can be obtainedfrom SIEP on reouest.

V l . 3 H r S D e t e c t o rT u b e s ( M a n u a lS a m p l i n g ) The detector should be acculate in pelfolmance for the range of concentration requiled and simple to operate. The detectol usuali1,-incorporates a hancl-opelated aspilating pump, with a colour metric detectol tube that plovides an integral scale reading gladuated in ppm HrS. A type of cletectol that leqniles lefelence to glaphs or charts is n o t r e c o m m e n d e da n c l s h o u l d n o t b e u s e c l .

Vl.4Testingand Calibration Electronicsystems (fixed) shall be veriiied fol acclllacl'.speeclof Ali H-S detectionsvstelr-qancleqtrrpn'rent l ' e s i ) o n s ea n d o p e l a t i o n r j e f f i c l e n c vn s l l c l ' n l a n u f a c t u i ' e r " sr ' € ' c o m m e n c l a t r oInn. a c l c h t r o n . s e n r i c o n d t t c t o it'r ' p e o f s c n s o l s s i - r a l l r e e x i l o s e c lt o a r - rH , S t e s t m i x t t r l e a t i r f i ' e q u e n r ' 1o' f at least once evel'\' tu.o ntonths.

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51

l

lI I

HSE Manual EP 95-0317HydrogenSulphide(HzS)in Operations Portable systems A 1'eliablefield caiibration kit shor"rldbe provicled by the eclttipment manufacturer. This should be used to verify the monitors at least once a da1'ol shift and always before initial use. Detector tubes The pump used with the detector tubes should be checked for leakage before use according to the manufacturer's instructions. A stock control system should be in place to ensule that adequate supplies are maintained and that the tubes are in date. Procedural coverage All velification and maintenance activities on the detection equipment shall be carried out and recolded throughout its life time as per manufactttreL's instructions. Procedural coverage must be transparent to all parties invoived. Fol exampie it would include the initiation of maintenance if equipment fails verification. The records must be traceable and auCitable and should form the basis of the performance indicators to be deveioped for each individual element of the gas detection system as well as for condition based maintenance. The periodic evaluation of equipment perfolmance wilI serve to raise awareness of its reliability, availabiiity, performance and maintainability. A maintenance management system plovides a convenient environment to achieve all of the above.

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AppendixVll RespiratoryProtectiveEquipment

VII APPENDIX RESPIRATORY PROTECTIVE EQUIPMENT Vll.1 General It should be noted that full face masks do not seal ploperly on beards or with the wearing of spectacles, with the result that positive pl:essure can be lost, thus permit,ting ingress of contaminated air from the surroundings. For breathing apparatus @A) it should be checked that every bottle is full prior to use. The contents, especially for a iarge non-portable bottle, may not be what is written on it. Confirmatoly air quality check-sshould be applied to bottles which are not filled and transported under full company control. Both pl'essure/demandand positive plessure systems ale avaiiabie. For use in an HoS atmosphere oniy a positive plessure system is recommended. The main types of respirator are described below. More detaiis can be found in the SSC guide 'Hydrogen Sulphide', Section 7 (Ref. 1).

Vll.z Self-Contained BreathingApparatus(BA) This self-contained breathing apparatus consists of compressed air cylinder/cylinders calried on the wearer's back. Air is supplied to the fuli face mask via a flexible hose through a plessure reduction and demand valve. The system can be obtained either in the 'demand' or'positive pressure' mode. In the positive pressure mode the possibility of pulling in toxic vapour alound the seal of the face mask is minimised. Cylinders of 1200, 1800 and 2400 litres are readily available from the manufacturers. The amount of ail remaining in the cyiinder(s) is easily checked by the wearer by means of a pressure gauge fitted to an extension tube attached to the front harness and by an audible low pressure alarm. This type of equipment in the 'positive pressule' mode is recommended for use in H"S contaminated environments up to a maximum of 2 per cent (20,000 ppm)

Hrs' Vll.3 GompressedAirline BreathingApparatus These sets consist of a full face mask attached to either a remote set of cylinders containing compressed air or to a compressor. The bank of remote cylinders or the compressor should never be left unattended whilst users ale connected. The face mask is connected to the bank of compresseclail cylinders or the compressor via a flexible hose and pressure regulator. The hose should be of a construction capabie of withstanding chemical attack and ki.nking under pressur-e.In the case of the compressor it may be necessary to include a filter downstream of the compressor to remove any contaminants. The compressed air hose breathing apparatus with a remote set of cylinders is recommended for use in an l{'S contaminated envilonment up to a m a x i m u m o f 2 p e r c e n t ( 2 0 . 0 0 0p p m ) H r S . The supply dilectly from a compressor is less reliable and thelefore not recommended.

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HSE Manual EP 95-0317HydrogenSulphide(HzS)in Operations

V l l . 4 C a s c a d eA i r B r e a t h i n gS y s t e m This equipment. used typically on drilling rigs. combines the complessed airline system of VII.3 with the self-contained breathing apparatus of'WI.2 by providing with the latter a possibil:ty of connecting into a compresseclarrline supply. The self-contained bleathing appalatus set ailows the pelson to leave the hazard area when necessarv.

Vll.s EscapeBA Sets An auxiliary self contained air supply as desclibed in VII.2 but rated fol less than 15 minutes is suitable only for escape or self rescue use. Gas mask canister type breathing and demand type (negative pressule) equipment as described below are not recommended for use for the l'easons grven in VII.6.

Vll.6 ChemicalCanisterRespirators These respirators consist of a full face mask connected to a canister by means of a flexible tube. The canister contains an adsolbent material selected for the specific toxic gas, in this case HoS, which it removes from the inhaled air'. The canister of adsorbent is for one time use only and must be discarded after use, regardless of how short the usage was. While breathing in, a negative pressure is developed inside the face mask and, if a poor face seal exists, HrS could enter the mask. As these respirators have no independent air supply they must not be used in atmospheres where the oxygen content is less than 21 per cent vol. The nominal protection factor of this type of equipment is from 50 to 400 (eg with a 500 ppm HrS atmosphere, protection factor 50, wearer breathes l0 ppm HzS). The length of time of adequate protection varies according to the exposure time and the concentration of HrS. There is no indication of remaining adsorbent capacity or point of saturation. There is also a limited shelf life for chemical canisters. Because of the problems outlined above, the use of chemical canister respirators is not recomnrended for service in HrS environrnents and due to their low protection factor these chernical canister respirators should not be used in drilling or workover operations. It is important to distinguish between the various types of such chemical adsorbent respirators which are on the market as some offer insufficient margin of safety. The key points are: '

they must have a full face mask

.

the canistel must contain sufficient adsorbenf The canisters which strap to the beit are generally large enough. Cartridges which fit directll' to the mask usually contain rnuch less adsorbent.

Although air-supplied escape sets ale lecommended, chemical cartridge respirator-s may be considered, on a lirnited, carefulll' selected basis, for emergency escape pur?oses, providing the following are observed: . use only in H"S concentrations of less than 200 ppm .

use only full face mask designs

.

r'eliably establish that cluantit5' and cairacitv of aclsorbent is sufficient fol purpose

o

set up a r.'egularmaintenance pl'ogramme to ensLu'ethe integlity of the masks

54

EP 95-0317Revisron0 5 October1995

AppendixVll RespiratoryProtectiveEquipment set tlp a tl'alntng pr.'ograntmeto ensule proper use and maintenance of the respirators set up administration to ensure canisters/cartriciges are discarcleclwhen the exnir.v date on them is reached or if they have been usecl (ie seal broken).

V l l . 7 C a r ea n d M a i n t e n a n c eo f B A E q u i p m e n t Breathing apparatus in its entilety shouid be checkeclat least monthly ancl details of the inspection and any maintenance recorded. A11work on bleathing apparatus rn,hich includes maintenance, inspection and cylinder refilling shoulci only be carrieci out by technicians competent in such work. The competencies should be clear'ly defined and checkecl.The responsibiiities for carrl"ing out the work should also be clearly defined. The quaiity of breathing air shoulcl be regularly checked. Problems of poor visibility and freezing of exhaiation valves may be encounterecl when using self contained breathing apparattts in sub-zero temperatures. Fult face pieces shouid be designed so that the incoming fresh air sweeps over the inside of the eyepiecesto reduce misting. Anti-misting compounds may be used.to coat the insicie of the eyepieces to reduce misting at room temperatures ancl d.own to temperatures approaching 0oC. Full face pieces are available rvith inner masks that clirect exhaied air through exhalation valves and, when properly fitted. are more likely to provide adequate visibility at low temperatures. At very low temperatures the exhalation valve may collect moisture and either freeze open, allowing the wearer to breathe contaminated air, or freeze closed.thereby preventing normal exhalation. Dry ail suitabie for respiration should. be used.with selfcontained and compressed ail line breathing apparatus. The clew point of the breathed. gas should be appropriate to the ambient temperatures (preferably not exceeding -b0 oC at atmospheric pressure). High plessure connections on self-contained breathing apparatus may leak because of metal contraction at low temperatules but the only penalty is likely to be outwar.cl leakage. For further details see: '

SSHC Guidelines 1989 - Personal Plotection Equipment Guicle G,ef. 15)

o

standards for breathing air qtrality

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- American

ANSI CGA G-7.1 i11ef. i6)

British

BS 4275.Sect.5.6.3. 1,I974 (Ref.17)

Australian

AS 1716App.E 19S4@ef. 18)

Gelman

DIN 318E(Ref.19)

} F

33

s u l p h i d e( H z S )i n o p e r a t i o n s H S E M a n u a l E P 9 5 - 0 3 1 7H y d r o g e n for personnelin H2Sareas levelsof protection Table vll.1 Recommended R ecommendedP rotecti on l evel - w here H 2S concentrationis known not to exceed200 P P m

R ecommendedprote ct ion level - where H2S concentration is known to exceed 200 pPm

Type of s i tu a ti o n

E x a mp l e s

V is i ts , ins p e c ti o n s

Ou ts rd ev i s i to rs , ma n a g e me nat u d i ts, engineers,draftsmen on fieldvisit. M a i n te n a n c e supervisorinsPecting worksite

Moni tor

Moni tor. Escapeset carried or cl oseto hand

B*

2

Norm a l operations

Operatorchecking i n s tru m e nre t a d i n gs, stoppingistarting p u m p s ,b u t e x c l u di ng any livework such as s a mp l i n go r ta n k dipping

Moni tor

Moni tor. Escapeset carried or cl oseto hand

B.

?

Work out of rangeof ' H2 S -l i v e '

Moni tor P a i n ti n gw e l d e dl i n es in pipe track,road re p a i rstre , n c hd i g gi ng, repairinglightfittings

Moni tor. Escapeset carried or close to hand

B'

No.

I

equ i p m e n t, pip i n g e , tc 4

W o rk sn e a r 'H2S-live' equ i p me n t, pip i n g ,e tc but u n l i k e l y to disturb them

W o rk l i k e l y to disturb ' H2 S -l i v e ' equrpment, p i p i n ge, t c

56

Any work nearflanged Moni tor. Escapeset carriedor p i p i n gp, u m p s , vessels,comPressors, cl oseto hand etc in which H2Scontainingfluidscan escapethrough flanges,seals,vents or breathervalvesinto th e i mme d i a te atmosphere

B'

Moni tor. Escapeset with mask at readY

c*

Moni tor. TestingnewlY c o mmi s s i o n ero d tati ng E scapeset carri edor M o d i fY i ng c l o s et o h a n d e q u i p me n t. pipingwhere stresses could be transmittedto . d j u s t i ng l i v ep i p i n g A a n dc a l i b r a t i n g ' w e t ' of c o m p o n e n ts i n s tru m e n ts

B'

Moni tor. Escapeset with mask at ready.

C+E

A t l eastone standbyw i th B .A . SET

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AppendixVil RespiratoryprotectiveEquipment Table vlt'1 Recommendedlevelsof protection for personnelin H2s areas(continued) No.

fa

Type of situation S am plin ga n d dipping

Ex a m p l e s T a k i n gg a s o r l i q u i ds ampl es D i p p i n ga ta n k

Recommendedprotection level (for all H2S concentrations) Moni tor B.A.set - mask fitted At leastone standbywith B.A. set

F+E'

7

Openinglive equipm e n t

T u rn i n ga s p a d e ,re m o vi ngbl ank Moni tor F+2E* to allowgas test B.A. set - mask fitted M a k i n ga g a s te s t At leasttwo standbywith B.A. set (at leastone if fully depressurised)

I

Leaking equipm en t

O p e ra ti o n ai nl v e s ti g a ti on of l eak. Op e ra to irs o l a ti n gl e a k i ng e q u i p me n t

Entryintolow lyingarea

IU

'1 4 t l

Note:

Moni tor B.A. set - mask fitted At leasttwo standbywith B.A. set

Wo rk o n ta n k b u n d so r in pi pe trenchesand culverts

Moni tor Escapeset if gas test shows H2S free Mask fittedif not gas tested Accessto tanksvia bundledarea At leastone standbywith B.A. set rntry into trntryIntovessels,tanks, I I Monitor I vesselor other b u i l d i n g so r c o mp a rtments Escapesetpermissible onlyonce space c o n ta i n i n gp ro c e s se q u i pment I isolated,gas I confined freed and air flow w h i c hm a y c o n ta i nH 2 S i n the establ i shed. atmosphere B.A. set - mask fitted At leasttwo standbywith B.A. set (at l eastone i f i sol atedand gas i freed) | Entryinto Arrivalat unmannedplatformor Monitor suspected productionfacilitywhere integrity B.A. set mask fitted unmonitored of H2S detectionsvstemsis in At leasttwo standbywith B.A.set area doubt

F+ 2E .

B+E* OR F+ E

B+E* OR F+ E

F+ 2E *

'H2S

concentration' refersto concentration of hydrogensulphidein the atmosphere. For liquidstreamstake concentration in equilibriumgas at atmosphericpressure. Escapesets to be used only if the enduranceis sufficient for the lengthof the escaperoute. ' F or ex plan a ti o n o f p ro te c ti o n l e v e lc l a s s i f i catton, see Tabl e4.3.

EP 95-0317 Revision 0 5 October 1995

57

AppendixVlll TypicalProcedures

APPENDIX VIII TYPICALPROCEDURES V l l l . 1S p h e r eR e m o v a l A sphele removal exercise in an H"S risk area lequiles three persons as a minimum. Two actually carrying out the job and the third observing from a safe position away from the launcher. As a minimum, four sets of self-contained breathing apparatus mus be prepared, function tested and declaled fit for usage. One for each of the two persons carrying out the loading, one for the observer anci one spare kept with the observer in r safe area. Portable continuous H,S monitols must be checked priol to commencement r work as must the personal HtS detector worn b1'the observer.

\-

1.

The previously checked self-contained breathing apparatus is donned by the three persons. Face masks left off.

2.

The portable continuous H,,S monitors are positioned around the receiver and turned on.

3.

HrS accessrestriction notices a1'eplaced at all necessary points.

4.

A11downwind work is halted and personnel cleared.

5.

The observer takes up his upwind position, ensuring unobstructed watch of the two carryrng out the work.

6.

Close the upstleam valves of the sphere receiver in-coming line.

7.

Close the downstream valves of the sphere receiver in-coming line.

8.

Open the line to vent betrveen the double block valves on the sphere receiver incoming line.

9.

Commence the gradual depressurising of the sphere receiver via the depressuring line to flare or vent. Check pressure on the gauges on the sphere receiver.

10. Once fully depressurised close off the depressurising valve. \!,

11. The two persons carrying out the work should now put on their breathing apparatus face masks havrng first opened the supply from the cylinder and then tested the face seal. 12. Open the drain valve and flush with r,vaterfrom a separate top connection. Alternatively purge rvith nitrogen to flare or vent. 13. Stop flushing, open door'. remove debris with a (non-meta1lic) rake and transport wetted debris in the dedicated container. Be aware of the effect of pyrophoric iron suiphide. 14. Remove sphere. 15. Close the receir-et'door'.ciose the dlar.n vall'e and ciose the flush connection. 16. Ciose the iine to vent between the cloublebiock valves on sphele receiver inlet line. lT.

Open the clorvnstream valves on the inle.t to the sphele leceiver.

1E. SlowiStrel)r'essttt'isethe lecervel' anci ciri';e out vu'atervapour with gas to the vent or flat'e -qvstent.Leali checks on the ciool seal must be made thloughout the r e l ) r ' e s s lui s n t i o n .

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59

i

HSE Manual EP 95-0317HydrogenSulphide(HzS)in operations 19. Two pelsons carrying or-rt, the work move to a szr{'eulea ancl may then r.emoveface m asks. 20. The sphere receiver should be ieft r'eacll'fol the next sirhering operation ciepenclent o n l o c a l O p c o ' sp r o c e d u r e s . 21. Remove all equipment usecl on the iob and clispc.rsc, of cleblis in accord.ancewith waste mana gement procedur.es.

Vlll.2ProcessStreamSampling Vlll.2.1Introduction This guideline deals with the sampling of sour product: '

AII accessways to the sampling point should have HrS warning notices posted..

'

AII equipment necessary for the sampling mtrst be thoroughiy checked.and positioned ready for the samphng to take place.

'

If pressurised sample cyiinders ale to be used, the cylinder must have a valid. pressure test certificate and be stowed/transported in a purpose-built secure container with ventilation holes. Prior to the sampiing taking place the control room supentsor must be informed.

'

AII safety equipment being used must be function-tested prior to usage.

'

The sampler should be equipped with a self-contained breathing apparaLus.

'

An observer positions himself upwind in a safe unobstructed area from which he has a clear r-iew of the sampler at all times.

.

Work in the downwind locations is stopped immediately prior to samplittg taking place.

.

The sampler must work from an upwind position even if he has a self-contained breathing apparatus on.

'

On completion of sampling, the sample containers must be clearly identified and should have an HoS warning label attacheci. The container with the sample should not be tlansporred in an enciosedvehicle. A carrier must be given warning for the transportation of samples containing HrS.

Vlll.z.zGuidelinesfor takinga pressurisedsample The schematic in Figure VIII.l shows a typical layout for pressurised. sample taking. The pipework eithel side of the quick couphng trni.onsis ieft in situ rvhen permanent sampling points ale established. The pressule cylindel containing the sample is transported to and from the labor.atorl'. The sampli.ng cylinder (or sampie bomb) may arrive at the sampling location either. pressurised (inert gas, ie N2) or under a slight vacuum. When a liquid sample is taken and vapour break or,rtis to be kept to a minirnum then the pressurised (inert gas) methocl can be used. The paltially evactrated cylindel can be usecl for gas samples.

60

EP 95-0317Revrsion 0 5 October1995

AppendixVlll TypicalProcedures 1.

Priol to conltecting the pressure cy-lindel to the sampling pipework the quick coupiing seal rings should be inspected. If any signs of deteriolation are er,rclent then a replacement seal shoulcl be fitted.

2.

Connect the cylinder to the sampiing pipervork by tightening the quick coupiings. Oor iiquid samples the disk T must be at the top of the veltically mounted cylinder).

3.

Close valves C and F

4.

Fully open valves D, E, A and H slorvl)'. (If liquicl, valve H remains closecl).

5.

Slowly open valve B. Check the cluick unions for leaks. Fuliy open valve B. The cylinder is now under sampie conditions.

Vlll.2.3For a gas sample 6.

Slowly open valve G allowing flow through the cyiinder. (The return line downstream of valve H returns to a palt of the process which is at a lower pressure than the sampling point). Once a suitable through flow has been alloweci (for purging, etc).

7.

Close valves H, G, E, D, A and B.

8.

Slowly open valve F, thereby venting the pipework between valves E and G.

9.

Slowly open valve C, thereby venting the pipework between valves D and B.

The cylinder quick couplings can now be undone and the cylincler prepared for transportation. Both sides of all quick couplings should be closed off.

Vlll.z.4For a liquid sample For liquid sample points valve F shouid be routed to a part of the process with a lower pressure than the sample point. Valve C should also route the same way. 6.

\/alve F should be slowly opened and as soon as a small amount of liquid passes, valve F is closed.

7.

Close valves D. E. B and A.

8.

Slowly open valve F and depressurise between valves E and G.

9.

Likervise slowly open valve C and deplessurise betrveen valves D and B.

The cyltnder couplings can be undone and the cyiinder plepared fol transportation. l..iote: It is essential that the cylindel is in a vertical position with the disc T at the top. Disc T indrcates which end of the cyiinder has the internal ullage tube. The space above the tube allows fol expansion of the hquid. Prior to using a pressure cyiindel for liquid sampling, rock the cyiinder gentiy to ancl flo. If a rattling sound comes from within the cylinder reject it, thi-s noise most probably' indicates that the ullage tube has detached fr,'omthe cyiinder top. It could be extremely dangerous to use a cylinder rvithout the ullage tube. Expansion of the enciosedliquid could cause the cvlinder ro burst.

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61

HSEManua|EP95-03lTHydrogenSulphide(HzS)inoperations Fol fulthel

.

details see:

API RP 44' (Ret' 20)' sarnpiing Petloleum Reservoit'Fir-rrcls

.AnalysisofoilFielciWater.sAPIRPa5CRef.2l). (schematic) arrangement FigureVlll.1 Typicalgassampling To Process

To ClosedDrain

62

EP 95-0317Revrston0 5 October1995

AppendixlX Exampres of H2s Area cfassification Systemsin Use

APPENDIXIX EXAMPLESOF HZSAREA CLASSIFICATION SYSTEMSIN

USE

To iilustlate how opcos have actuaiiy implementecl the guiclelines given in chalrter.(i two examples are briefly descr.ibeclbelow.

lX.1 ShellExpro shell Expro have established five ciiffer.ent ar.eas as far as Hos hazar.ds ar.econce'necr, reference Hydrogen sulphide Gtriclance by UESE/14 @"f. ;;;. ' H2S-0 areas - he.e HoS will be encounte'ecl during normal oper.ations. ' H2S-1 areas - hele thele Itlay be a Presenceof HoS uncler.normal oper.atrng conditions' II,S'1 area-scan be macle safe fo. r,oor'fing by the application of iaicl down procedures: this cannot be achieveclfor..H.'S-O areas. ' H2S-2 areas - these ar.enolmall-r'HrS-free but may be contamrnateclby a -svstem malfunction, leakage ol olrening of enclosecllines or equipment. There ale two types of H"S-2 aleas. Majol and IVIinor. In an H2S-2 Major area a release would carry a risk of serior,s, irrle.rersible effects, which in practice means an Hts concentration in air exceeciing 200 ppm. i1 an H2s-2 Minor u."" the potentiaj Hos concentration would never exceed 200 ppm ancl the "i=. therefore only carries tir. '.irf" of minor (reversible) effects. Non-H2S areas - these are always fi'ee of H"S rvhich in practice means that the concentlation in air cannot exceecl5 ppm by iny reasonable mechanism.

lx.z PDO PDo distinguishes,as far as accidentalreleases a'e concerned(which excluciesplannecl exposule)'between three diffelent categoriesof onshole pr.oductionfacilities: Sweet, Low Risk Sour and' High Risk So...?"cilities, refelencereport TR/00 yg4by TSE/11 Gef' 23)' The basis for the classificationis that no person should intentionally be expo-ced to a concentrationof HrS of 10 ppm in air or more u,ithout ppE being worn. Facilitl'specificreleasescenarioshave been cleveiopecl but in all casesassessedto date the dominant factor in detelmining H=s concentratron in air ^isL the U ^ r vu concentration \ - ' r r u s r r r ' r c t L r u ru r l H.,s of in the procgss str.eam. .

Sweet area An area is ciassified a.ssrveet rvhen no process stream in that a'ea has an H"S concentration that exceed-q50 ppm. This is commensurate rvith ";;;.;;'" potential concentration in ail of ies.sthan 10 ppm based on estimatecl clilution following a release.

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63

i

.-

-.

-:---

-.--*,-!4..J-

S u l p h i d e( H z S )i n O p e r a t i o n s H S EM a n u a t E p 9 5 - 0 3 1 7H y d r o g e n .

Lovv Risli Sour if a concentration above 50 ppm but below A faciiiry is classifiectas Low Risk Soul which could give rise to a maximum 500 ppm HrS is present in the process stream. concentratj.onin air of 200 PPm'

.

High Risk Sour 500 ppm HrS'which could A facility with process stream containing above the vicinity of the leak, requires a potentially expose a person to above 2Ooppm in potential leaks. If the results show that cletaileclassessment of the clispersion fro.r, 200 ppm in air at a point two metres there is a creclible risk of exposure to above classified as High Risk Sour' from the release sour.ce,the facihry wili be

specifu detection systems (fixed or Based.on these area classifications, both Opcos pro."dttres ancl warning notices along the portable), PPE, entry, work and emergun.y guidelines provided in this document'

64

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Glossary

GLOSSARY A g l o s s a r y o f c o m m o n i y u s e d t e r r r r si n H S E i s g i v e n i n b o t h E P g S - 0 1 0 0H S E Management Systems and EP 9i)-i)300C)vervie',vHazarcis anci Effects Management Process.

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65

References

REFERENCES 1 2 3 4 5 6

Hydrogen Sulphide, SSC.December1936. DEP 32'31'20'1l-Gen, The instrumentation of fire and gas cletection s1'stems,SIPM. ISo 3864,safetl' colours and Safety Signs, ISo, 1gE4. BS 5378.Safetl'signs and colours, BSI. BS 1553,Specification for graphical sl,mbols for general engineering, BSI. safety signs and colour cocling, ssc, september19g1.

7

RP 49 Recommended Practices for Safe Drilling of Wells Containing Hydrogen Sulphide, ApI. April 19g7.

8

Guidelines for Entry into Confinecl Spaces, SSHC.ApriJ 1gg2.

I

Gas-freeing and cleaning of oil storage Tanks, ssHC, April lggg (anci AddendumApril 1992).

10 RP 55. Recomrnended Practices for Conclucting Oil and Gas producing ancl Gas Processing Plant Operations Involving H,vdrogen Sulphide, ApI, Febr.uary1995. 11 MR-01-75,Material Requirements for SSC resistant metallic materials for oilfield equipment, NACE, 19g4. L2 DEP 37'40.20.31-Gen, Line Pipe for use in oil and gas operations under sour conditions. SIPM. 13 DEP 31.38.01.15-Gen, Ep piping classes,sIpM. 74 DEP 32.80.10.10-Gen, Instrurnentation - protection Functions, SIPM. 15 Personal Protective Equipment Guicle section 6.8 Re spiratory Prote ctive Equipment, SSHC,June 1ggg. 16

AIJSI cGA G'7 '1, Compressed Gas Association Comrnodity Specification G7.1 Breathing Air Grade D, A\ISi.

1 7 BS 4275:1974, Recornmenclations for the selection. use and maintenance of respiratory protective equiprnent. BSI. 18

AS 1776,Respiratory Protective Devices, Standard.s Association of Australia, 1984.

1 9 DII'I 3188,Compressed air for respiratory equipment, safetl- requirements and testing, DIN. September1gE4.

2 0 RP 44, Recommended Practice for Sampling Petroleum Reservoir Fluids, API, January 1gGG.

2T R'P45'Recommended Practice for Anall,sis of Oil-Field Waters. Seconcl 22

Edition, API, November'r g6E(Reiss'eclJuly lgs 1). H1'drogen sulphiclc Guicla'ce. trESE/14. shell Expro

LT\.

2 3 TP'/001194. Sweet. Low Risk Sour and High Rish sour by TStr/11,pDO.

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67

HydrogenSulphideSafetyTraining Course Duration:

Twenty four Hours (3 Days)

Intended for:

Trainers instructing perconnel working in an offshore or onshore environment where the presence of Hydrogen Sulfide is known or suspected.

Aim:

To give pensons the necessarT skills to impart the nece$sary information to provide students with the skills necessary to work in an HzS environment

Objectives:

Upon completion of this course, the attendee should be able to: 1. Describe the physical properties and hazards of H2S and S()2. 2. Show an understanding of proper work procedures while working in the presence of IIzS. 3. Show an understanding of HzS detection and monitoring. 4. Show an understanding of the contingency plan. 5. Show an understanding of basic rescue in an H2S environment 6. Safely don and starf up Self Contained Breathing Apparafus

(scBA). 7. Understand and explain an Air Loop (Cascade)system. 8. Passa wriften test Contenfi

A. Introduction and Registration B. Aims and Objectives

S::iffi:"lffiu*o orHzs and soz E. F. G. H. I.

Hazards of HzS, Symptoms of Exposure Respiratory Profection Moniforing & Detection Safety Procedures & Contingency Plan Rescue Techniques - basic

ii 3:ffiffi# fff#:.1h"s

anAirLoop sysrem.

L. Written Test Approvals:

Association of Risk Management, Maersk Oil, Qatargas, Rasgas

As English is the predominant language used during emergencies, the attendees must be able to understand spoken English. It is the responsibility fhe sponsoring company fo ensure that the attendee is physically fit