ADNOC-COPV4!10!2010 - COP on Safe Handling & Working With Hydrogen Sulphide

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RECORD OF REVISION Revision No.

Date

Section/Page

Reason

Copyright The copyright and all other rights of a like nature in this document are vested in Abu Dhabi National Oil Company (ADNOC), Abu Dhabi, United Arab Emirates. This document is issued as part of the Manual of HSE Codes of Practice (the “Manual”) and as guidance to ADNOC, ADNOC Group Companies and independent operators engaged in the Abu Dhabi oil & gas industries. Any of these parties may give copies of the entire Manual or selected parts thereof to their contractors implementing HSE standards in order to qualify for award of contracts or for the execution of awarded contracts. Such copies should carry a statement that they are reproduced by permission of ADNOC, and an explanatory note on the manner in which the Manual is to be used. Disclaimer No liability whatsoever in contract, tort or otherwise is accepted by ADNOC or any of its Group Companies, their respective shareholders, directors, officers and employees whether or not involved in the preparation of the Manual for any consequences whatsoever resulting directly or indirectly from reliance on or from the use of the Manual or for any error or omission therein even if such error or omission is caused by a failure to exercise reasonable care. All administrative queries should be directed to the Manual of HSE Codes of Practice Administrator in:

Environment Health & Safety Division, Supreme Petroleum Council Abu Dhabi National Oil Company, P.O. Box : 898, Abu Dhabi, United Arab Emirates. Telephone : (9712) 6023782 Fax: (9712) 6668089 Internet site: www.adnoc.ae E-mail:[email protected]

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CONTENTS

Page

i. 

PURPOSE ......................................................................................................... 5 

ii. 

DEFINITIONS .................................................................................................... 5 

iii. 

EXISTING LAWS............................................................................................. 11 

1 

INTRODUCTION ............................................................................................. 12 

2 

PREVENTION.................................................................................................. 14 

2.1 

Site Selection................................................................................................... 14 

2.2 

Classification of Hydrogen Sulphide Areas ..................................................... 14 

2.3 

Definition and Size of Red and Yellow Zones ................................................. 16 

2.4 

Access Control to Classified Areas ................................................................. 18 

2.5 

Layout and Design........................................................................................... 19 

3 

DETECTION .................................................................................................... 22 

3.1 

Personal Alarms .............................................................................................. 22 

3.2 

Fixed Detectors................................................................................................ 22 

3.3 

Detector response times.................................................................................. 23 

3.4 

Hydrogen Sulphide Alarms.............................................................................. 24 

3.5 

Hydrogen Sulphide Exposure Monitoring........................................................ 24 

4 

CONTROL ....................................................................................................... 25 

4.1 

Permit to Work ................................................................................................. 25 

4.2 

Activities Requiring Breathing Apparatus ........................................................ 25 

4.3 

Surveys............................................................................................................ 26 

4.4 

Start Up............................................................................................................ 26 

4.5 

Worker Competency........................................................................................ 27 

5 

MITIGATION.................................................................................................... 28 

6 

EVACUATION, RECOVERY & RESCUE ....................................................... 29 

6.1 

Emergency Plans and Procedures.................................................................. 29 

6.2 

Escape Routes in Yellow and Red Zones....................................................... 29 

7 

EDUCATION & TRAINING ............................................................................. 30 

7.1 

Training for All Personnel ................................................................................ 30 

7.2 

Hydrogen Sulphide Competency..................................................................... 31 

7.3 

Working with air lines....................................................................................... 33  Document No. ADNOC-COPV4-10

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7.4 

Training of Emergency Response Teams ....................................................... 33 

7.5 

Hydrogen Sulphide Trainers............................................................................ 34 

8 

ENFORCEMENT ............................................................................................. 35 

9 

PERSONAL PROTECTIVE EQUIPMENT ...................................................... 36 

9.1 

General Requirements .................................................................................... 36 

9.2 

Emergency Escape Masks .............................................................................. 36 

9.3 

Self Contained Breathing Apparatus ............................................................... 36 

9.4 

Air-line Fed Breathing Apparatus .................................................................... 37 

9.5 

Fit Testing ........................................................................................................ 37 

9.6 

Facial Hair........................................................................................................ 38 

9.7 

Eye-Glasses .................................................................................................... 39 

10 

COMPETENCY................................................................................................ 40 

11 

TOXIC GAS REFUGES................................................................................... 41 

11.1  Design of toxic gas refuges ............................................................................. 41  11.2  Offshore installations ....................................................................................... 42  12 

EMERGENCY PLANNING ZONES ................................................................ 43 

13 

ASSESSMENT OF THE IMPACT OF HYDROGEN SULPHIDE ................... 44 

14 

REFERENCES ................................................................................................ 45 

APPENDIX I PROPERTIES OF HYDROGEN SULPHIDE

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i.

PURPOSE This Code of Practice addresses the requirements for safe handling and working with hydrogen sulphide. The purpose of this document is to ensure that risks to people from hydrogen sulphide as a result of ADNOC Group operations are prevented, controlled and mitigated so that the risk to people is as low as reasonably practicable (ALARP).

ii.

DEFINITIONS Accident

An event or chain of events which has caused fatality, injury, illness and/or damage (loss) to assets, the environment, company reputation or third parties..

ACGIH

American Conference of Governmental Industrial Hygienists – the authority which supplies TLV®s and STEL®s to be used by ADNOC Group companies as specified by the ADNOC COP V3.01, Framework of Occupational Health Risk Management.

ADNOC

Abu Dhabi National Oil Company.

AEGL

Acute exposure guideline levels are published by the US Environmental Protection Agency to assist in Emergency Planning. See appendix 1

Best Practice Note

Safe Handling and Working With Hydrogen Sulphide – Best Practice Note. See Reference [1].

Buddy System

A person assigned to assist someone who is working in a hazardous activity such as working in a hydrogen sulphide area whose duties include remaining alert to hazards, giving of alarms, keeping rescue lines clear, cross-checking that the correct procedures are being followed and similar activities. The buddy should be protected to the same degree as the person he is assisting.

Bump Test

A short exposure to a test gas which demonstrates that the sensor and alarm are operational, without carrying out a calibration Document No. ADNOC-COPV4-10

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Cascade system

Facility to allow self-contained breathing apparatus to tie-in into an air supply manifold to allow extended work in a Red Zone.

Contractor

Any person or company employed under contract (irrespective of period of contract or employment).

Competence

The ability to perform a particular job in compliance with performance standards. Will usually require the necessary blend of skills, training and experience.

DTL

Dangerous Toxic Load, defined in Ch 13

Emergency Escape Mask

Breathing apparatus which allows escape from a toxic gas classified area in an emergency, regarded in this COP as a positive pressure, selfcontained breathing air type

Green Zone

Area where hydrogen sulphide risk is low – See Section 2.2

Hazard

Potential source of harm. Source, situation, or act with a potential to cause harm. Note: in the context of international standards, the potential harm may relate to human injury, damage to the environment, damage to property, damage to reputation, or a combination of these.

HSE Management System

The company structure, responsibilities, practices, procedures, processes and resources for implementing health, safety and environmental management. HSEMS, ADNOC-COPV1-09.

HSEIA

Health, Safety and Environmental Impact Assessment – A systematic process identifying HSE impacts. A demonstration required for ADNOC Group Company sites to demonstrate that health, safety and environmental issues have been adequately dealt with.

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HSECES

HSE Critical Equipment And Systems – Part of an installation and such of its structures, plant equipment and systems (including computer programmes) or any part thereof, failure of which could cause or contribute substantially to; or a purpose which is to limit the effect of a major accident or any accident with severe or catastrophic consequences as defined in the ADNOC Group Guideline on HSE Risk Management [Ref: 12]. See ADNOC Code of Practice Volume 6 [Ref: 11]

Incident

An event or chain of events which has caused or could have caused fatality, injury, illness and/or damage (loss) to assets, the environment, company reputation or third parties.

Injury

Physical harm or damage to a person resulting from traumatic contact between the body of the person and an outside agency, or from exposure to environmental factors.

Personal Hydrogen Sulphide Detector

Device which must be worn by all personnel entering hydrogen sulphide classified areas, which will alarm if the hydrogen sulphide concentration reaches the STEL®.

Personal Hydrogen Sulphide Monitor

Device which can be used to confirm compliance with the eight-hour TWA TLV® limit, which integrates total personal hydrogen sulphide dose over an eight hour period.

PPE

Personal protective equipment

Probit

A statistical measure which relates probability of fatality or injury to time and concentration see Appendix I

Red Zone

Area where hydrogen sulphide risk is high – see Section 2.2

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Risk

The measure of the likelihood of occurrence of an undesirable event and of the potential adverse consequence, which this event may have upon people, assets, the environment, or economic measures and reputation of the company.

Safe Haven

Protected location designed to allow people to shelter in the event of an accident, sometimes referred to as a Temporary Refuge Shelter. Protection is provided against toxic gas and smoke ingress, fire and explosion blast, in some cases also explosion projectiles.

SCBA

Self-contained breathing apparatus, regarded in this Cop as positive pressure type. Breathing apparatus that can be used without other support, so that the user is mobile. Often supplied with a cascade mode that allows tie-in to a remote air supply via a supply manifold.

SIL

Safety integrity level, a measure of the degree of risk reduction provided by a safety measure. Defined in standard IEC 61508, Functional Safety.

SLOD

Significant Likelihood of Death – DTL at which there is a probability of fatality.

SLOT

Specified Level Of Toxicity

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STEL®

Short term exposure limit – a 15-minute TWA exposure that should not be exceeded at any time during the work day, even if the 8-hr TWA is within the TLV®-TWA. The TLV®-STEL® is the concentration to which it is believed that workers can be exposed continuously for a short period of time without suffering from (1) irritation, (2) chronic or irreversible tissue damage, (3) dose-ratedependent toxic effects, or (4) narcosis of sufficient degree to increase the likelihood of accident, injury, impaired self-rescue, or materially reduced work efficiency. The ACGIH recommended STEL for hydrogen sulphide is 5ppm. Compliance with the TLV®-STEL® will not necessarily protect against these effects if the daily TLV®-TWA is exceeded. The STEL® is a registered trademark of the ACGIH. See Appendix I

TLV®

Threshold limit value – TLV®s refer to airborne concentrations of chemical substances and represent conditions under which it is believed that nearly all workers may be repeatedly exposed, day after day, over a working lifetime, without adverse health effects. The ACGIH recommendation for the hydrogen sulphide TLV® is 1ppm average over 8 hours. The TLV® is a registered trade mark of the ACGIH.

Toxic Gas Warning Level

Gas concentration threshold at which an alarm device shall give a warning and shall serve to bring personnel to the muster point

Toxic Gas Alarm Level

Gas concentration threshold at which an alarm device shall give a warning and shall serve to trigger personnel evacuation.

Toxic gas refuge (TGR)

Protected location designed to allow people to shelter in the event of a hydrogen sulphide leak.

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TWA

Time-weighted average exposure. The TLV®TWA concentration for a conventional 8-hr workday and 40-hr workweek, to which it is believed that nearly all workers may be repeatedly exposed, day after day, over a working lifetime, without adverse health effects. For hydrogen sulphide the ACGIH recommended TLV®-TWA is 1 ppm averaged over eight hours. This could be made up of 2ppm for 4 hours and zero for the remaining four hours. However, exposures above the TLV®-TWA up to the TWA-STEL® should be less than 15 minutes, should occur no more than four times per day, and there should be at least 60 minutes between successive exposures in this range.

Yellow Zone

Area where hydrogen sulphide risk is medium – see Section 2.2

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iii.

EXISTING LAWS Current legislation of relevance to the subject of this Code of Practice is: •

Federal Law No. 8, 1980, Regulation of Labour Relations and Order Issued in Implementation Thereof.

The following ADNOC Codes of Practice are generally relevant to the safe handling and working with hydrogen sulphide: •

COP V1.02 – Health, Safety and Environmental Impact (HSEIA) Requirements;

•

COP V3.01 – Framework of Occupational Health Risk Management;

•

COP V4.01 – Framework of Occupational Safety Risk Management;

•

COP V4.04 – Personnel Protective Equipment;

•

COP V4.05 – Non-routine Operations;

•

COP V5.02 – Crisis and Emergency Management.

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1

INTRODUCTION Hydrogen sulphide is a colourless gas commonly associated with ADNOC Group Company oil and gas operations. It is highly toxic causing fatality after as little as ten seconds’ exposure to high concentrations. It has been responsible for the death of many people worldwide, including many cases where people have been overcome attempting to rescue colleagues. This Code of Practice has been developed following a number of fatal accidents in Abu Dhabi oil and gas industries involving hydrogen sulphide. It incorporates the conclusions of the ADNOC Group Company Workshop – H2S – A Silent Killer. This Code Of Practice provides regulations to allow ADNOC Group Companies to adopt a consistent and safe approach to handling and working with hydrogen sulphide. It applies to all ADNOC Group Company facilities and operations with the potential for exposure of people to concentrations of hydrogen sulphide above the TLV® or for acute exposure which could be lethal or injurious. This COP makes a clear distinction between TLV®-TWA and TLV®-STEL values which are intended for worker protection against chronic health effects, and therefore require monitoring and release reduction engineering at the work site, but does not require alarms and toxic gas warning and alarm levels, which are intended to protect against acute injurious exposure, and therefore require alarms and retreat or evacuation from the workplace. This COP applies to all ADNOC Group Company operations and activities where there is a hydrogen sulphide hazard to people. It includes, but is not limited to, onshore plant, pipelines, offshore platforms, and drilling and servicing of wells. These requirements must be taken into account for all stages of the facility lifecycle whenever such a hydrogen sulphide hazard exists. They also apply to ADNOC Group company operations where potential personnel exposure to hydrogen sulphide is of an intermittent nature such as when a vessel where there is normally no hydrogen sulphide hazard is alongside a platform handling hydrocarbons containing hydrogen sulphide. This Code of Practice outlines: •

Prevention of personnel exposure by appropriate site selection and layout, and by equipment selection, design and integrity monitoring. It also includes a hydrogen sulphide area classification scheme (Section 2).

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•

Detection of dangerous levels of hydrogen sulphide, including requirements for personal hydrogen sulphide detectors and for fixed detection systems and alarm settings. (Section 3);

•

Control of activities that can potentially lead to a release of hydrogen sulphide. This includes such diverse operations as confined space entries and boarding an offshore installation where hydrogen sulphide may be present. It covers requirements for permit to work systems, activities for which breathing apparatus is specifically required, surveys for occupational health compliance and start-up controls (Section 4);

•

Mitigation of the effects of hydrogen sulphide releases, including risks arising from fires involving hydrogen sulphide which can generate sulphur dioxide, a highly toxic combustion product (Section 5).

•

Evacuation Recovery and Rescue requirements in the event of a hydrogen sulphide release, including the development of emergency response plans and testing through exercises (Section 6).

•

Education and Training requirements to ensure that all personnel on site including contractors, temporary workers and visitors are aware of the hydrogen sulphide hazards to which they can be exposed, are able to carry out their work with due attention to those hazards and know what to do in the event of an emergency involving hydrogen sulphide. It lists training requirements for different personnel groups including hydrogen sulphide trainers. (Section 7);

•

Enforcement arrangements detailing group company authority and responsibility (Section 8);

•

Personal Protective Equipment requirements and usage covering the different types of PPE and including facial hair requirements and fit testing (Section 9);

•

Competency requirements including use of hydrogen sulphide competency certificates (Section 10);

•

Toxic Gas Refuges and their use in an emergency, including the requirement to determine if installation of a TGR would reduce risks to as low as reasonably practicable (Section 11);

•

Emergency Planning Zone requirements (Section 12); and

•

QRA use for site selection, development of emergency plans and for analysis potential risk reduction measures (Section 13). Appendix I includes reference data on the physical and toxic properties of hydrogen sulphide. Document No. ADNOC-COPV4-10

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2

PREVENTION

2.1

SITE SELECTION New facilities (defined for the purposes of Section 2.1 as facilities where front end engineering design has not commenced at first issue of this COP) must be sited sufficiently far from public locations, including housing and roads so as not to exceed either the individual risk or the societal risk as stated in the ADNOC Code Of Practice Volume 5 – Risk Assessment And Control of Major Accident Hazards [Ref: 12]. This applies even where the new facility is to be constructed on an existing group company site. For onshore sites, worker accommodation, such as construction camps, and places where off-duty workers may be present must be sited so as not to exceed, even temporarily, either the individual risk requirement or the societal risk as stated in the ADNOC Code Of Practice Volume 5 – Risk Assessment And Control of Major Accident Hazards [Ref: 12]. The risk from all relevant facilities, both new and existing, must be considered. Compliance with these requirements must be demonstrated using QRA/dispersion calculations in the HSEIA, and should take into account the anticipated duration of exposure. For further details refer to Section 13 of this COP. For offshore facilities, including relevant vessels, accommodation, muster points, lifeboat embarkation points must be sited to reduce the risk to all personnel to as low as reasonably practicable taking into account Sections 6 and 11 of this Code of Practice and as stated in the ADNOC Code of Practice on HSEIAs [Ref: 2].

2.2

CLASSIFICATION OF HYDROGEN SULPHIDE AREAS Locations where a hydrogen sulphide hazard exists must be classified according to the potential threat from hydrogen sulphide based on the precautions needed to allow people a good chance to escape in the event of an accidental release of hydrogen sulphide:

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Zone Red

Hazard High

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Description Areas where potential exists for exposure to such high concentrations of hydrogen sulphide that fatality may occur due to relatively short exposure (minutes). Definition of the size of the red zone is given in section 2.3

Yellow

Medium

Green

Low

Unclassified

None

Entry Requirements SCBA set or air line set to be worn and in use on entry and at all times when H2S is present, alternatively for older plant, BA Set or positive pressure escape set to be carried at all times. Personal hydrogen sulphide detector worn at all times provided risk is shown to be acceptable (see text 2.4). Access control or personnel tracking. Authorised and trained personnel only. Hydrogen sulphide competency certificate required for entry to Red Zone. Emergency Escape Mask (carried) and personal detector (worn) Hydrogen sulphide competency certificate required for entry to Yellow Zone

Areas outside the red zone where potential exists for exposure which may be injurious to personnel after relatively short exposure (minutes). See section 2.3 for the approach to calculating the extent of the yellow zone. Group companies may choose to define the entire process area of a plant or well area as a yellow zone, for convenience in controlling access and checking that persons entering are properly equipped and trained. Areas outside the yellow zone where personnel would be able to No restriction safely evacuate in the event of an accidental release without the need for PPE, but where exposure above the TLV® is possible. Exposure to hydrogen sulphide above the TLV® not credible. No restriction

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Group Companies must classify all parts of all facilities, including laboratories, offshore platforms and remote locations where hydrogen sulphide may be handled according to the above scheme and must control access as detailed below. Sub-sea pipelines do not need to be considered, except at terminations on platforms and shore. Cross-country pipelines only need to be considered at valve stations, pigging stations, compressor stations and the like. Any change to a facility which results in a change in status of a location to a more hazardous zone, e.g. the introduction of sour fluids into equipment that normally handles lower hazard fluids, cannot be made until reclassification of the relevant area has been made. The above classification represents a mandatory minimum requirement. Areas may be classified as Red or Yellow Zones even when they are technically a less hazardous zone to simplify the application of controls and the usage of PPE. For example, an entire facility can be defined as a Yellow Zone, even where one area might technically be a Green Zone. 2.3

DEFINITION AND SIZE OF RED AND YELLOW ZONES The purpose of defining hydrogen sulphide classified areas is to ensure that safety measures taken provide a level of safety such that the risk level is acceptable or in the low tolerable region and risk ALARP can be demonstrated. One principle used for determining the presence and amount/size of hydrogen sulphide is that of “time to protect”. Special protection is required in an area where there is insufficient time to self-evacuate or to don emergency breathing apparatus in the case of a hydrogen sulphide release. Such a principle, if applied to the largest accidents, such as pipe ruptures, leads to very large red zones. A probabilistic approach is therefore preferred, in which classified areas are defined in terms of the level of risk of there being insufficient time to don emergency protective equipment is in the acceptable or lower part of tolerability region. A red zone is considered to exist if there is a possibility of hydrogen sulphide release which could be rapidly lethal. This is defined as a location where: •

There is a possibility of release of hydrogen sulphide from a pressurised source through a 10 mm hole which will give a concentration of =/ >1000 ppm at a distance of 1 m from the hole.

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There is a possibility of a release from a vent or safety valve which will give a concentration of =/>1000 ppm at a distance of 1 m from the hole.

A yellow zone is considered to exist if there is a possibility of hydrogen sulphide release which could be rapidly injurious. This is defined as a location where: •

There is a possibility of release of hydrogen sulphide from a pressurised source through a 10 mm hole which will give a concentration of =/>50 ppm and < 1000 ppm at a distance of 1 m from the hole.

•

There is a possibility of a release from a vent or safety valve or similar low pressure source which will give a concentration of =/>50 ppm and < 1000 ppm at a distance of 1 m from the hole.

For onshore and new offshore installations the size of the red zone is defined as the area where the location specific risk from hydrogen sulphide releases is greater than 10-5 per year, taking into account the frequency of releases, jet and plume dispersion, the geometry of gas jets, the possibility of jet impingement on the ground, structures, piping or equipment, wind speed and atmospheric stability, and the duration of release,. For onshore and new offshore installations the mandatory minimum size of the yellow zone is defined as the area where the possibility of concentrations of gas exceeding 50 ppm is greater than 5×10-4 per year *, taking into account the frequency of releases, jet and plume dispersion, the geometry of gas jets, the possibility of jet impingement on the ground, structures, piping or equipment, wind speed and atmospheric stability. For existing offshore installations, The size of the Red Zone is defined as the area where the location specific risk from hydrogen sulphide releases (*equivalent to a toxic gas concentration of 1000ppm) is greater than 10-4 per year, taking into account the frequency of releases, jet and plume dispersion, the geometry of gas jets, the possibility of jet impingement on the ground, structures, piping or equipment, wind speed and atmospheric stability and the duration of the release. For existing offshore installations the mandatory minimum size of the yellow zone is defined as the area where the possibility of concentrations of gas exceeding 50 ppm is greater than 5x10-3 per year, taking into account the frequency of releases, jet and plume dispersion, the geometry of gas jets, the possibility of jet impingement on the ground, structures, piping or equipment, wind speed and atmospheric stability.

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ACCESS CONTROL TO CLASSIFIED AREAS Entry to Red Zone areas must be controlled and secure to prevent unauthorised persons accidentally wandering into the area. Access to Red Zones shall be limited to personnel holding a valid certificate for hydrogen sulphide competency as detailed in Section 7.2. A system must be in place for personnel to register in / out when entering or leaving Red Zones, or a wireless personnel tracking system used, so that it is possible to establish who is present in the event of an emergency. Personnel entering Red Zones must have a personal portable hydrogen sulphide detector which will alert them if the hydrogen sulphide level rises to the Toxic gas warning level, and that the emergency escape mask shall be donned immediately on alarm. Best practice in the red zone is to wear and use breathing apparatus at all times. This requires appropriate design of the plant facilities (see section 2.5). For existing plants, where this can be justified on an ALARP basis, protection may be provided to personnel in Red Zones wearing breathing apparatus or carrying it ready for rapid use at all times. The types of breathing apparatus which are suitable is discussed in Ch.9. When carrying out work involving opening of equipment containing hydrogen sulphide, positive pressure breathing apparatus must be worn and in use. Where registration of entry /exit to a Red Zone is not reasonably practicable, for example where entry into a Red Zone is by helicopter landing on a platform which is a Red Zone in entirety, then Group Companies may establish an alternative system that fulfils the intent of the registration system: controlling entry to authorised persons only and determining who is present in the event of an emergency. Many offshore personnel tracking systems will already fulfil this requirement. As such Helicopters are not permitted to land in Red Zone. There must always be at least two independent escape routes out of a Red Zone. In order to simplify access controls, one of the escape routes can be designated for emergency exit only, and entrance to the Red Zone via that route prohibited. The escape/entry routes shall be decided based on the prevailing wind direction and other relevant locational considerations. All personnel entering Yellow Zones must have all necessary PPE to facilitate escape in an emergency as detailed in Sections 3, 6 and 11. Personnel entering Yellow Zones must have a personal portable hydrogen sulphide detector which will alert them if the hydrogen sulphide level rises to the Toxic gas warning level, and that the emergency escape mask shall be donned immediately on alarm.

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The demarcation between Green and Yellow Zones must be clearly established by the use of floor markings and pictographic warning signs. (If the boundary of the yellow zone is defined as the process area security gate, markings may be made just at the gate(s)). For access to sour gas fields or wells, the access point shall be along the access road(s), at the edge of the field if the entire field is regarded as a yellow zone, or at the road approach to the individual well or well cluster. Warning signage shall be placed at this location. If the access point is not manned, telephone numbers to the field control centre shall be displayed on a sign, and procedures shall require that persons approaching the well or entering the field a) have proper PPE and b) inform the control centre.

2.5

LAYOUT AND DESIGN This section applies to all new facilities (defined for the purposes of Section 2.3 as facilities where front end engineering design has not commenced at first issue of this COP) and, where reasonably practicable, to modifications to existing facilities. Facilities with Yellow or Red Zones must be designed and laid out to: •

Minimise the size of Red Zones;

•

Allow simple segregation of the site into Red and Yellow Zones;

•

Plants shall be designed for minimum intervention requirements, so that operator and maintenance team visits to the red zone are minimised.

•

Plants shall be designed to facilitate air line working in the red zone

•

As far as possible working at height or on elevated platforms in the red zone should be avoided by design.

•

Avoid venting of fluid containing > 5ppm hydrogen sulphide direct to atmosphere for any reason. Such gases should be routed to a suitable acid gas recovery system or flare;

•

Where breaking of containment is required to take equipment out of service for maintenance or other reason, the level of isolation from hazardous fluids must be a minimum of provable double-block and bleed for temporary isolations lasting less than a shift and full positive isolation for longer isolations. Note that short term isolation is required to allow swinging of a spectacle plate or inserting a spade to achieve Document No. ADNOC-COPV4-10

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positive isolation. Refer to [Ref 2] for further details. Ensure that such equipment can be fully purged prior to opening and that facilities are present to allow control of any residual pyrophoric hazards; •

Selection of metallic materials of construction must conform with ISO 15156 or better. (If better, the improvement must be documented by test results following ISO or NACE International standards). Deviations or changes must be subject to a management of change review process;

•

Flares and associated sterile areas must be designed to avoid exposure of any personnel to hydrogen sulphide beyond STEL® / TLV® limits in the event of flame out. Flares handling material containing hydrogen sulphide must be designed to avoid exposure of personnel to sulphur dioxide combustion products beyond the STEL®/TLV®;

•

Avoid placing equipment in confined spaces, pits, or low lying areas where hydrogen sulphide could build up and where entry may be required from time to time e.g. for maintenance, sampling etc. Where it is not reasonably practicable to avoid such arrangements, facilities must be provided to avoid the need for man entry into the confined space on a regular basis.

•

Provide a fixed hydrogen sulphide gas detection system in accordance with Section 3;

•

Primary access to all elevated platforms where planned access (i.e. access to carry out scheduled activities including maintenance) or escape under air may be required must be provided by staircase as opposed to vertical ladder. Secondary escape may be provided by vertical ladder where the provision of a secondary staircase is not reasonably practicable. In such cases the vertical ladder shall be designed to allow safe and efficient escape wearing self contained breathing apparatus;

•

Fail safe downhole safety valves must be provided on all new wells where the well fluid contains more than 0.05 mole percent hydrogen sulphide;

•

Devices whose primary purpose is to detect, control or mitigate hydrogen sulphide hazards must be defined as HSE Critical Equipment or Systems (HSECES’s) so that maintenance and testing can be properly controlled and verified. For further details see the ADNOC Code of Practice: Verification of Technical Integrity [Ref: 11];

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•

Demonstrate that the sectionalisation of plant by ESD valves and the time required for emergency blowdown of plant sections is such as to reduce risks to people to as low as reasonably practicable;

•

Demonstrate that the sectionalisation of pipelines reduces risks to people to as low as reasonably practicable.

•

Office, canteen and accommodation areas should preferably lie outside the yellow zone. This should be achieved by design of well, process and safety systems. Where this proves impossible, one or more rapidly accessible toxic gas refuges must be provided.

Compliance with these design and layout points must be demonstrated in the HSEIA. All the above must be considered as potential measures to reduce risks to ALARP levels for existing facilities. For existing plant, where back fitting of some measures may be difficult, the quantified ALARP principle shall be applied quantitatively to determine reasonable levels of practicability. Precautions to be taken for facilities abandonment, well abandonment shall also be considered in HSEIA based on ALAP principles.

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3

DETECTION

3.1

PERSONAL ALARMS Personnel, including temporary workers and visitors entering Yellow or Red zones must be provided with personal hydrogen sulphide detectors which will alarm in the event of exposure to hydrogen sulphide concentrations at or exceeding the toxic gas warning level of 10 ppm. Personal hydrogen sulphide detectors must have the following minimum specification: •

Cannot be switched off either deliberately or accidentally;

•

Alarm at the toxic gas warning level in such a way as to be recognisable under all foreseeable conditions including in high noise areas;

A system must be in place to ensure that personal hydrogen sulphide detectors are properly maintained. Devices must be tested and calibrated as per the manufacturer’s recommendations or more frequently or whenever the sensor is exposed to high concentrations of H2S, if this is determined necessary for reliable operation. Bump testing is permissible for routine testing on a frequent basis, but actual calibration testing shall also be made at an interval in accordance with manufacturer’s recommendations.

Some personal detectors are able to provide TWA® total dose and STEL® event recording. Some have a resolution down to 0.1 ppm, making them useful as chronic exposure monitoring device, in addition to providing accidental exposure warning. Note that most personal alarms and monitors on the market in 2010 with fixed alarm levels are not set to 10 ppm. 3.2

FIXED DETECTORS All sites with Yellow or Red zones must evaluate their requirement for a fixed hydrogen sulphide detection system in accordance with the performance needed to meet ADNOC risk Criteria and accordingly provide, operate and maintain the system which will reduce risks to ALARP level. Group companies must define the purpose of the fixed detection system, e.g. to warn of a toxic gas release passing from a plant area to a non-plant area, or to detect toxic gas passing beyond the boundary fence. The fixed detector Document No. ADNOC-COPV4-10

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system must then be designed so that it fulfills the intended purpose, with reliability sufficient to meet the risk and ALARP criteria. Alarms from fixed detectors must be set at the toxic gas warning level of 10 ppm for warning and at the toxic gas emergency level of 15 ppm for immediate evacuation. The detectors must be designed and placed so as to minimize the frequency of nuisance alarms and to provide a high probability of detection in an actual emergency. Hydrogen sulphide alarms shall be operable during the entire period of plant operation or where this cannot be done as for example during steaming out; the area shall be evacuated up to a predetermined safe distance, or to a distance determined to be safe by the use of portable hydrogen sulphide detectors. The possibility of change in wind speed, wind direction, and of release size must be taken into account. For plants in remote areas with minimum manning and for remote wells and manifolds, fixed gas detection networks shall be designed to ensure detection and alarming sufficient to: •

Guarantee detection and alarming for releases which threaten persons in the any local operator room, with a reliability sufficient to meet the risk and ALARP criteria.

•

Guarantee detection and alarming of releases which could threaten persons approaching the area along approved routes with a reliability sufficient to meet the risk and ALARP criteria.

•

Guarantee alarming at the central control room and emergency centre for any releases which could be a threat to the public, with a reliability sufficient to meet the risk and ALARP criteria.

For work teams in the field, provision of fixed detection systems will often be impractical. For these cases, detection shall be provided in the form of mobile detectors and personal alarm monitors. The detection needs to be backed up by means of a portable wind sock (for example attached to a small mast or vehicle) because the origin of the release will often be unknown to the work team, and may be remote. 3.3

DETECTOR RESPONSE TIMES The response time for alarm systems is an important parameter. Many of the worst releases can be over in a few minutes. Typical response times for electrochemical and MOS hydrogen sulphide detectors are 30 seconds up to 2 Document No. ADNOC-COPV4-10

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minutes. Some newer MOS sensors based on newer technology have response times as fast as 10 seconds, and optical point detectors can have response times down to 1 sec. The response time for open path detectors depends on the path length, but can be as short as 1 sec for paths of a few meters, and 10 sec for paths up to 100 meters. Since emergency shutdown and evacuation alarm times depend very much on detection times, companies must take response times into account when selecting detectors. Response time should be minimized, consistent with reliability and reasonable (ALARP level) cost. 3.4

HYDROGEN SULPHIDE ALARMS Confirmed releases of hydrogen sulphide shall be alarmed with a continuous high-pitch tone and flashing beacon audible / visible at all relevant locations. Alarms shall be compliant with EN ISO 7731 and EN ISO 11428 [Ref: 13 and 14]. The audible alarm signal be a continuous high pitch siren tone and a flashing blue light.

3.5

HYDROGEN SULPHIDE EXPOSURE MONITORING Hydrogen sulphide surveys are required to ensure that persons are not exposed to continuing or intermittent injurious levels of hydrogen sulphide Initial scoping studies for finding potential areas of hydrogen sulphide exposure can conveniently be carried out using hand held electronic monitors, these are available with sensitivities in the ppb region, but for TWA measurement purposes, instruments which measure down to the 0.1 ppm level are more suitable, and more readily available as standard industrial equipment. Instruments with a probe are often more convenient for identifying the source of small releases from valves or rotating equipment. Once the hydrogen sulphide survey has been defined, the survey can be carried out using dosimetry badges, absorption tubes, or personal recording monitors.

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4

CONTROL

4.1

PERMIT TO WORK All facilities where a hydrogen sulphide hazard exists must operate a PermitTo-Work system. Permits-To-Work in Yellow and Red zones must not be issued without pre-work site inspection, which must include as a minimum: determination of potential for release, a task risk assessment (TRA), correct isolation, appropriate controls/PPE, buddy system and requirements for continuing detection. All lockouts, interlock removal, including the movement of locked valves and similar operations undertaken in Yellow and Red Zones must be controlled by permit and verified using the buddy system.

4.2

ACTIVITIES REQUIRING BREATHING APPARATUS Air-line fed positive pressure supplied air breathing apparatus must be used for all prolonged operations where there is a risk that personnel may be exposed to hydrogen sulphide concentrations above the TLV® as a result of equipment failure or human error during the operation but not limited to or unavoidable release. This includes all of the following operations whenever such a hydrogen sulphide risk could exist: •

Breaking of containment, including swinging spectacles or inserting spades;

•

Taking samples, including product quality activities where the possibility of dangerous levels of hydrogen sulphide exist;

•

Confined space entry; and

•

Local venting of equipment, including instruments during calibration or testing, where personnel are so close to the vent that they could be exposed to concentrations above the STEL®.

•

Drilling activities on rig floor, flaring, BOP, Mud tanks, shale-shakers etc wherever the H2S levels exceed STEL®.

Positive pressure breathing apparatus must be used for these activities. Selfcontained breathing apparatus (SCBA) may be used when the task involved is very short, for example sample taking. Generally air-line breathing apparatus is preferred.

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Design to avoid continuing exposure to hydrogen sulphide must be preferred to the use of breathing apparatus wherever this is practicable. Further details of breathing apparatus requirements are given in Section 9. 4.3

SURVEYS Where not already carried out, Group Companies must carry out surveys of operations such as sampling and venting to determine the need for breathing apparatus and any limitations on the time personnel can be present to avoid exceeding the allowable time-weighted average dose. These surveys should take into account hydrogen sulphide concentration arising from unavoidable emissions during the operation together with background emissions from such sources as leaking valve stems or local venting. Where it is necessary for personnel to wear breathing apparatus to avoid exceeding the STEL® (5 ppm for 15 minutes) or the time-weighted average concentration (average of 1 ppm for 8 hours), Group Companies must repair or replace equipment, modify the operation to be carried out, or take other appropriate steps to avoid the need for breathing apparatus wherever this is reasonably practicable.

4.4

START UP ADNOC Group Companies must ensure that there is independent verification of readiness before introduction or reintroduction of substances containing greater than 500 ppm hydrogen sulphide in the vapour phase after let down to atmospheric pressure. This applies both to initial commissioning and start-up and to start-up following a shutdown where breaking of containment, introduction of lockouts or overrides, or other activities have occurred which, if not properly reinstated, could compromise the ability to prevent, control or mitigate hydrogen sulphide hazards. In this context, an independent verifier must be familiar with the plant, but must not be part of or report to the individual or team who are responsible for commissioning, starting up or reinstating the plant.. The scope of the verifier must include checking of all relevant items such as: •

Correct position of isolations, including spades;

•

Reinstatement of overrides; and

•

Successful completion of leak testing where relevant;

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WORKER COMPETENCY All personnel involved with operations involving materials containing hydrogen sulphide must be competent to perform the activities required of them. Personnel working in Green, Yellow or Red Zones must have the level of competency for those Zones; training requirements are given in Section 7, whilst specific competency requirements are given in Section 10.

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MITIGATION Where evolution of hydrogen sulphide from an accidental spill of liquid with the potential to harm people is foreseeable, then the following must be provided unless demonstrated to be not reasonably practicable: •

Secondary containment; and

•

A means to limit the evolution of hydrogen sulphide, such as blanketing with foam.

Hydrogen sulphide is a reactive gas which is susceptible to explosion when mixed with air. Appropriate provisions for explosion prevention and consequence mitigation shall be taken, such as rapid ESD, and explosion protection measures. ADNOC group companies storing solid sulphur shall determine the possibility of hydrogen sulphide being released from solid sulphur, in the case of both properly specified product and off spec production. If injurious concentrations can be generated, appropriate ventilation shall be provided as well as appropriate personal protective equipment.

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6

EVACUATION, RECOVERY & RESCUE

6.1

EMERGENCY PLANS AND PROCEDURES The general requirements for the development and testing of emergency plans and procedures at group Company facilities are given in the ADNOC COP V5.02 Crisis and Emergency Management [Ref 3]. Where a hydrogen sulphide hazard exists, the emergency plans and procedures must take into account the nature and extent of those hazards, especially:

6.2

•

Any need to alert the public or third parties of a hydrogen sulphide hazard beyond the boundary fence;

•

The control of visitors, temporary workers and contractors, including contractors under the supervision of a third party, any of whom may have limited knowledge of Arabic or English;

•

The need for trained rescue teams to retrieve personnel overcome by hydrogen sulphide;

•

The existence and nature of Green, Yellow and Red zones and how access between them is controlled;

•

The requirement for a toxic gas refuge where personnel can seek shelter whilst a gas cloud disperses (see Section 11);

•

Any special requirements for personnel on air-lines in the event of either a nearby hydrogen sulphide release or other type of emergency elsewhere on the facility; and

•

The time required to don emergency escape mask or breathing apparatus.

ESCAPE ROUTES IN YELLOW AND RED ZONES All escape routes on facilities where a hydrogen sulphide hazard exists must be passable by personnel wearing self-contained breathing apparatus. Escape routes shall be identified and marked (see COP V5-02). For fixed installations a means of emergency communication to the control room/emergency centre shall be provided.

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7

EDUCATION & TRAINING

7.1

TRAINING FOR ALL PERSONNEL All personnel, including temporary workers who will not always be accompanied, entering a site that has a hydrogen sulphide hazard must be trained to understand: •

Hazards of hydrogen sulphide;

•

The meaning of the zone designation;

•

The requirements for entering a Yellow or Red Zone;

•

The understanding of warning signs related to hydrogen sulphide;

•

Recognising and reporting a hydrogen sulphide leak;

•

Use of personal hydrogen sulphide detectors;

•

The meaning and types of alarms, both general and from personal hydrogen sulphide detectors;

•

Actions to be taken in the event of an emergency;

•

Escape routes and importance of moving crosswind; and

•

What to do if a colleague is overcome by toxic gas.

Accompanied visitors must receive a briefing on the hazards of hydrogen sulphide, the use of emergency escape masks and escape procedure. This training must be site specific. This is in addition to other training that may be required for personnel to work safely. Personnel must undergo refresher training on a yearly basis. Training records must be maintained by the Group Company and audited annually.

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Visitors who are accompanied by a Group Company Employee at all times must be appraised of: •

Hazards of hydrogen sulphide;

•

Use of personal hydrogen sulphide detectors

•

The meaning and types of alarms, both general and from personal hydrogen sulphide detectors; and

•

What to do in an emergency involving hydrogen sulphide.

Personnel who work at more than one site where hydrogen sulphide hazards exist, but whose duties are such that they will never enter Hydrogen Sulphide classified zones need only receive instruction in site specific issues as part of the formal site induction training and do not need to repeat the full hydrogen sulphide training at each new site. Such personnel must never enter hydrogen sulphide classified zones. 7.2

HYDROGEN SULPHIDE COMPETENCY Valid hydrogen sulphide competency certificates are required for all personnel: •

Entering Red or Yellow Zones; and

•

Working with breathing apparatus as a result of hydrogen sulphide hazards.

This is in addition to other entry requirements listed in Section 2.2. Group Company HSE departments can, at their discretion, issue such a certificate to anyone graduating from a hydrogen sulphide competency course that includes the following elements in addition to the topics noted in Section 7.1: •

Requirements for and reasons behind facial hair restrictions;

•

Requirements for entering Yellow Zones

•

Requirements for entering / leaving Red Zones including register in / out procedure and interface with the Permit-To-Work system;

•

Operational controls applicable for Red Zones (see Section 4); Document No. ADNOC-COPV4-10

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•

Understand the buddy system and the duties of a buddy (remain alert, give alarm, keep any rescue lines clear);

•

Consequences of not adhering to procedures;

•

Use of PPE required by operational controls, which must include both self-contained breathing apparatus, emergency escape mask and airline fed breathing apparatus;

•

Recognition of alarms and response;

•

Use of PPE in an emergency;

Before graduation and issue of a Hydrogen Sulphide Competency Certificate, personnel attending a hydrogen sulphide competency course must: •

Demonstrate understanding of the course topics;

•

Demonstrate the ability to correctly don an emergency escape mask within 20 seconds and SCBA in 45 seconds.

•

Demonstrate correct use of breathing apparatus; and

•

Demonstrate correct operation and use of air-line fed breathing apparatus.

The time period of 20 seconds to don an emergency escape mask (prechecked and ready for use condition), is based on tests carried out which indicate that this can readily be achieved. Hydrogen Sulphide Competency Certificates will be valid for 12 months, after which refresher training is required. Group Company HSE departments must audit third party hydrogen sulphide competency training providers before beginning to issue certificates and at least once per 12 months thereafter to ensure that training standards are maintained.

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WORKING WITH AIR LINES Personnel who will be working under air line supply must be tested for fitness. They must also demonstrate competency in:

7.4

•

Understanding of air line supplies

•

The importance of keeping lines free and untangled

•

The importance of having a person standing by to assist in case of difficulties

•

The ability to check connections and air supply

•

The ability to change over connections safely

•

Emergency air supply in case of air line failure

•

The procedure for escape

TRAINING OF EMERGENCY RESPONSE TEAMS Personnel in teams who will be responding to hydrogen sulphide emergencies must be trained in: •

Methods of rescuing personnel overcome by hydrogen sulphide;

•

The use of equipment they may be using for emergency response;

•

How to make the area safe e.g. performing isolations;

•

Means of communication; and

•

Treatment for personnel exposed to hydrogen sulphide.

Personnel must be able to demonstrate their competency in these subjects in a practical test before being allowed to take up their duties in an emergency response team. This is in addition to any other training which may be required for them to fulfil their function.

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HYDROGEN SULPHIDE TRAINERS All trainers providing hydrogen sulphide training for emergency response teams, hydrogen sulphide competency or for personnel working on a hydrogen sulphide site must be able to demonstrate working experience on sites where a hydrogen sulphide hazard exists and with the various forms of breathing apparatus and other PPE in which they will be training others. The competency of the hydrogen sulphide trainers must be subject to audit before a Group Company can issue a Hydrogen Sulphide Competency Certificate to graduates of that trainer. Trainer qualification shall be in accordance with ANSI/ASSE Z390.1-2006, Accepted Practices For Hydrogen Sulphide (H2S) Training Programs.

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ENFORCEMENT It is the responsibility of senior management to have oversight of compliance with this COP. Implementation of the requirements of this COP shall commence immediately on its issuance to the extent reasonably practical. Full implementation shall be ensured by the end of year 2013. Personnel who do not adhere to the requirements of this COP are not only putting their own lives at risk, but also those of their colleagues, emergency service and others working on and off site. Offenders shall be subject to disciplinary action up to and including removal from site. Personnel removed from any ADNOC Group Company facility for violation of this COP shall be prohibited from entering all ADNOC Group Company facilities. Organisations or groups carrying out design work, contractors or individual personnel who repeatedly fail to meet the requirements of this Code of Practice must not be considered for future projects, contracts or employment across the ADNOC Group of companies. Strict compliance with the requirements of this Code of Practice must be monitored. Audits of operational sites where a hydrogen sulphide hazard exists must be carried out as often as necessary to ensure continued compliance and at a maximum interval of 12 months.

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9

PERSONAL PROTECTIVE EQUIPMENT

9.1

GENERAL REQUIREMENTS The sections below detail the minimum mandatory requirements for personal protective equipment. Other restrictions may also apply, such as the ability to work safely in an area which may contain flammable gas.

9.2

EMERGENCY ESCAPE MASKS Hydrogen sulphide at emergency levels can cause difficulty in vision and short term blindness. Escape sets must be of full-face positive pressure or positive pressure hood type with an air supply of at least 10 minutes. The protection offered by a given respirator is contingent upon (1) the respirator user adhering to complete program requirements (such as the ones required by OSHA in 29CFR1910.134), (2) the use of NIOSH-certified respirators in their approved configuration, and (3) individual fit testing to rule out those respirators that cannot achieve a good fit on individual workers’. Hydrogen sulphide can cause severe irritation of the eyes and temporary blindness. For this reason, hood type escape masks are preferred. Goggles may be of some use, but only if they are put on before exposure to H2S because the goggles themselves can fill with gas. Full face mask types or hood types with positive pressure air supply are freed from gas as air is passed from the storage bottle to the mask.

9.3

SELF CONTAINED BREATHING APPARATUS Self-contained breathing apparatus (SCBA) must only be used for short tasks such as sampling, emergency response, for rescue activities and for entering and leaving Red zones. Where work activities longer than a few minutes require breathing apparatus, units must be capable of transfer to an air-line fed mode (cascade system) which must be used during the work. This is because of the finite capacity of self-contained apparatus compared to the extended capacity when air-line fed. Sufficient SCBA sets of appropriate capacity must be ready and available at all times to allow response to identified emergencies, in addition to those sets in use by personnel working in Red Zones, or engaged in activities which require breathing apparatus. The number, location and condition of the sets must be subject to yearly audit. The appropriateness of these arrangements must be

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verified by drills or exercises as often as necessary to ensure that SCBA sets will be readily available in an emergency. 9.4

AIR-LINE FED BREATHING APPARATUS Air-line fed positive pressure breathing apparatus must be used where there is a risk of hydrogen sulphide above the STEL® or when working in Red zones. Where this is impractical, work may be carried out using positive pressure escape sets which are worn and ready to be quickly donned, provided that this can be demonstrated to be acceptable on an ALARP basis. Air line fed positive pressure breathing apparatus is required to be used in all cases when equipment is being opened, if the equipment contains, or has a reasonable chance of containing, hydrogen sulphide. (Use of SCBA is allowed for very short operations, such as taking a single sample). Filter masks are not considered to provide adequate protection for use in Red Zones. Air shall be provided in compressed air bottles and cascaded to the breathing apparatus through a manifold. There shall be an alarm set to warn of low air supply pressure and it must be monitored at all times whilst the system is in use. Air line fed breathing apparatus must include a personal air reserve cylinder which can be used for escape in the case of air line supply failure. The bottles shall be refilled by a dedicated compressor located at a location free of hydrogen sulphide or other contaminant, and shall not have cross connection to any other air or gas system.

9.5

FIT TESTING All personnel who are required to use respiratory protection for hydrogen sulphide atmospheres, including use of an emergency escape mask during an emergency must pass a fit test for all face mask types they may be using. The fit test must: •

Be carried out by a competent person;

•

Quantitatively measure the fit factor (the ratio of substance concentrations outside the face mask, to those inside), which must be greater than 2000:1 to register a pass [Ref: 4];

A further fit test must be repeated and passed whenever: Document No. ADNOC-COPV4-10

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•

There is any change to the person which might compromise the integrity of the face mask such as from, facial hair, glasses, significant dental work or dentures, weight change and facial scarring;

•

There is any change to the mask style, size, material or manufacturer; or

•

Deemed necessary by the Group Company to ensure employee safety.

To be competent, the fit test operator should have adequate knowledge and have received adequate instruction and training in the following areas:

9.6

•

Regulations and Guidance

•

The Purpose and Applicability of Fit Testing

•

Procedures for Selection of Adequate and Suitable RPE

•

Fit Factors and Protection Factors

•

Examination Procedures for RPE, Identification of Maintenance Problems

•

Correct Donning Procedures and Pre-Use Fit Checks

•

Qualitative and Quantitative Face-Fit Testing

•

Sampling from the Face piece

•

Diagnostic Checks on Equipment

•

Correct Fit Testing Procedures, Purpose of the Fit Testing Exercises

•

Problem Solving

•

Capabilities and Limitations of the Fit Testing Equipment

•

Interpretation of Results

FACIAL HAIR ADNOC companies shall decide whether to allow personnel to have significant facial hair. If so, they shall provide appropriate breathing or escape apparatus Many types of respiratory protection, including many emergency escape masks, are incompatible with significant facial hair. If these types of breathing Document No. ADNOC-COPV4-10

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apparatus are used, personnel who may need to use respiratory protection in the course of their work or for escape in an emergency must not have facial hair that prevents tight-fitting of the mask provided. Compliance with the company facial hair requirement, where applicable, for all such employees, and contractors must be verified when the person first arrives on site and as often as necessary to ensure continued compliance. No person can be allowed to carry out duties or enter areas that require use of respiratory protection, who cannot pass the fit test specified in Section 9.5. At the Group Company’s option, personnel with facial hair may be given alternative respiratory protection which is compatible with their level of facial hair, provided the apparatus is suitable for the conditions under which it is to be used. However, the fit test specified in Section 9.5 must be carried out and passed before they can be allowed to enter zones or carry out activities that either require or potentially require use of the respiratory protection. Persons who will be working regularly in red zones, such as operators and maintenance personnel must not have facial hair which could cause inadequate sealing of breathing apparatus face-pieces or hoods. For accompanied visitors, if they have significant facial hair, appropriate (hood type) emergency escape masks shall be provided. 9.7

EYE-GLASSES (PRESCRIPTION GLASSES) Wearing eye-glasses can be incompatible with some forms of respiratory protection. Personnel who may need to wear respiratory protection and who normally wear glasses, either must be provided with suitable respiratory protection which is compatible with wearing eye-glasses, or must be given suitable respiratory protection containing prescription lenses. If neither of these is practicable, such personnel must not carry out activities which may require the use of respiratory protection, including for emergency escape.

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COMPETENCY ADNOC Group companies must verify that all personnel, including contractors, and temporary workers as well as employees, requiring Hydrogen Sulphide Competency Certificates have a valid certificate before they can be allowed to commence those duties for which the certificate is required. Expired certificates must be confiscated and destroyed. Correct certification must be verified on commencement of duties and at yearly intervals to confirm that refresher training has been carried out. Where verification cannot be obtained then retraining will be necessary before a new certificate can be issued. Specific competency requirements must be demonstrated at the completion of training for: •

Hydrogen sulphide competency (Section 7.2);

•

Emergency response team training (Section 7.3); and

•

Hydrogen sulphide trainers (Section 7.4)

•

Fit testing (section 9.5)

Refer to the specific parts of Section 7 for further details. Anyone unable to provide a practical demonstration of their competency must not be allowed to perform the respective roles.

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TOXIC GAS REFUGES Toxic gas refuges are protected locations where people can take shelter during a toxic gas release. Sites handling hydrogen sulphide and not already having designated safe havens shall evaluate whether the installation of a TGR is a reasonably practicable risk reduction measure. Some potential releases of hydrogen sulphide can travel many kilometres before dispersing to safe levels. In such cases one or more TGR may be required remote from the potential releases of hydrogen sulphide and for the benefit of third party populations. This possibility must be included in the evaluation. On offshore installations, the ability to safely leave the TGR / Safe Haven and evacuate the installation, for example following ignition of a sour gas release, must be considered as part of the TGR/Safe Haven evaluation and specification. An example of a typical TGR would be a pressurised building equipped with airlock doors which close automatically on either detection of hydrogen sulphide approaching the building or detection in the ventilation inlets.

11.1

DESIGN OF TOXIC GAS REFUGES Toxic gas refuges should be designed for purpose. In many cases where there is a possibility of hydrogen sulphide release, the release will either be at a small rate, or will be short lived, because the hydrogen sulphide inventory in equipment is limited. In other cases, such as close to sour gas or sour oil wells, or close to gas pipelines, gas releases may last for hours or days. For short lived toxic gas releases, an effective toxic gas refuge can be made by: •

Providing toxic gas detectors in the air intake, and arranging automatic shut off of the air conditioning and ventilation

•

Providing dampers in the air intakes which are automatically closed in the case of toxic gas detection

•

Eliminating small single room ventilation

•

Providing split unit air conditioning for individual rooms where centralised air conditioning is impractical

•

Sealing/locking closed all windows Document No. ADNOC-COPV4-10

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•

Providing two sets of doors so that the door inter-space functions as an air lock / weather lock.

•

Keeping the doors closed, or providing automatic door closing on toxic gas detection

•

Checking the ceiling and floor for possible routes of gas ingress, and sealing any leaks

For places where there is a potential for long duration toxic gas releases, all of the above steps must be taken, and in addition, the following steps are to be taken:

11.2

•

Check all potential ingress, by testing refuge leak tightness, and seal any leaks.

•

Provide a positive pressure safe air supply, either by providing bottled compressed air, or providing a filtered air intake of sufficient capacity.

•

Providing an evacuation or rescue strategy for the case of refuge engulfment for an extended period.

OFFSHORE INSTALLATIONS Offshore installations will require a temporary safe refuge (TSR) or Safe haven. The measures described above in section 11.1 will be needed. However, for offshore installations, protection against fire and explosion will generally be needed also. These provisions are outside the scope of this COP. For small platforms such as well head platforms, provision of a toxic gas refuge can be extremely difficult, or practically impossible. The risks to personnel on these platforms must be reduced to acceptable or ALARP levels by other means, such as reducing exposure and providing good emergency shutdown. Provision of rapid escape to attending boats, with boats preferably moored upwind (where possible) are additional means. Risk to boat crews from hydrogen sulphide shall be considered in QRA’s. In difficult cases, some of the techniques described in section 11.1 can be applied to service boats.

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EMERGENCY PLANNING ZONES The extent of hydrogen sulphide hazard zones for emergency planning purposes both off-site and on-site should be determined based on distances to the Acute Exposure Guideline Levels (AEGL) as published by the US EPA [Ref: 5] taking into account the anticipated duration of personnel exposure. The key AEGLs are: AEGL-1 The airborne concentration (expressed as parts per million (ppm) or mg/m3 of a substance at or above which it is predicted that the general population, including “susceptible” but excluding “hyper-susceptible” individuals, could experience notable discomfort. Airborne concentrations below AEGL-1 represent exposure levels that could produce mild odor, taste, or other sensory irritations. AEGL-2 The airborne concentration (expressed as ppm or mg/m3) of a substance at or above which it is predicted that the general population, including “susceptible” but excluding “hyper-susceptible” individuals, could experience irreversible or other serious, long-lasting effects or impaired ability to escape. Airborne concentrations below the AEGL-2 but at or above AEGL-1 represent exposure that may cause notable discomfort. AEGL-3 The airborne concentration (expressed as ppm or mg/m3) of a substance at or above which it is predicted that the general population, including “susceptible” but excluding “hyper-susceptible” individuals, could experience life-threatening effects or death. Airborne concentrations below the AEGL-3 but at or above AEGL-2 represent exposure that may cause irreversible or other serious, longlasting effects or impaired ability to escape. Examples of susceptible persons are old persons and small children. The AEGL values will therefore be conservative for the healthy working population. The current published AEGL values are given in Appendix I. In order to determine the size of the emergency planning zones, gas release and dispersion calculations are needed to determine the duration length, width and concentration of hydrogen sulphide plumes. These calculations shall take into account the inventory and corresponding duration of possible releases, and the reasonable worst cases of wind speed (1.5 m/s) and atmospheric stability (stability category F). Calculations should be made using a computer program which has been validated for the purpose, for the conditions, and for the type of releases which could occur. Document No. ADNOC-COPV4-10

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ASSESSMENT OF THE IMPACT OF HYDROGEN SULPHIDE When people are exposed to hydrogen sulphide the impact will depend on both the concentration of the gas in air and the duration of the exposure. Any calculations of the potential impact of hydrogen sulphide releases must take into account both these factors. Therefore, when QRA type calculations are undertaken to assess the hazards of hydrogen sulphide, including optimising protective features or in performing an ALARP analysis, the impact on humans must be assessed using a toxic load of the form: TL = ∫Cn.dt Where: TL = toxic load C=

concentration of hydrogen sulphide in air, which may vary as a function of time;

t =

time

n=

toxicological exponent

Units are usually ppm for concentration and minutes for exposure time. Units of mg/m3 and seconds are also given in some sources. Units for the toxic load will depend on the units used for concentration and time. It is important to check the units in use for any calculation. Values for n and the method of determining the impact of specific toxic loads published by the UK HSE [Ref: 6] or TNO [Ref: 7] are recommended.

Dangerous Toxic Loads (DTL) are specified in terms of SLOD (significant likelihood of death) and SLOT (specified level of toxicity) values which have been given by UK HSE. Probit, SLOT and SLOD values shall be used for calculation of toxic release in QRA.

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REFERENCES 1.

Safe Handling and Working with Hydrogen Sulphide – Best Practice Note, ADNOC-COPV4-11.

2.

ADNOC COP V1.02 – Health, Safety and Environmental Impact (HSEIA) Requirements, 2005.

3.

ADNOC COP V5.02 – Crisis And Emergency Management

4.

Control Of Substances Hazardous To Health, 4th Edition, 2002, Approved Code of Practice and Guidance, UK HSE.

5.

National Advisory Committee for Acute Exposure Guideline Levels for Hazardous Substances, US EPA, 1995.

6.

United Kingdom Health and http://www.hse.gov.uk/hid/haztox.htm

7.

Methods for the Determination of Possible Damage to People and Objects Resulting from Releases of Hazardous Materials, TNO “Green Book,” CPR 16E, The Hague, Netherlands, 1992

8.

Threshold Limit Values for Chemical Substances and Physical Agents, ACGIH®, 2010 – ISBN 978-1-607260-19-6.

9.

HPA Compendium of Chemical Hazards, Hydrogen Sulphide, UK Health Protection Agency 2009

10.

Hydrogen Sulfide, Oil and Gas, and People’s Health, Lana Skrtic, Master of Science Dissertation, Energy and Resources Group, University of California, Berkeley, 2006.

11.

Verification Of Technical Integrity, ADNOC Code Of Practice, Volume 601, October 2004.

12.

ADNOC Code Of Practice Volume 5 – Risk Assessment And Control of Major Accident Hazards, version 02, August 2009.

13.

EN ISO 7731, Ergonomics - Danger Signals for Public and Work Areas, Auditory Signals 2008

14.

EN ISO 11428 Ergonomics - Danger Signals for Public and Work Areas, Visual signals 2008

15.

ADNOC COPV1-09 on HSE Management System

16.

API RP 55 : Recommended Practice for Oil and Gas Producing and Gas Processing Plant Operations Involving Hydrogen Sulfide

17.

API RP 49: Recommended Practice for Drilling and Well Servicing Operations Involving Hydrogen Sulfide.

Safety

executive

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APPENDIX I

Properties of Hydrogen Sulphide

Hydrogen sulphide is a colourless flammable gas, which burns with a paleblue flame forming sulphur dioxide and water vapour. It has a very offensive odour similar to that of rotten eggs, which can be detected at concentrations between 0.0002 to 0.3 ppm. The chemical and physical properties are as follows:

Molecular Formula

H2 S

Molecular Weight

34.08

UN Number

1053

CAS Number

7783-06-4

Specific Gravity

1.19 [air = 1.0]

Boiling Point

-60.33 oC

Explosive Limits, by volume in air

46% upper

Auto-Ignition Temperature

260 oC

Solubility @ 20 o C

0.5 gm H2S in 100 ml water. Soluble in water. aqueous solutions of hydrogen sulphide are not stable.

4.3% lower

4 

NFPA 704 Code

0

4

GHS / CLP Classification

Signal Word Hazard statements

Danger

Danger Extremely Flammable Gas

Fatal if inhaled

Very flammable - F+

Very Toxic – T+

CHIP Classifications

Risk

R12

Extremely

Safety

S16

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flammable

Phrases

sources of ignition

Phrases

R26

Very toxic by inhalation

S36

Wear suitable protective clothing

R50

Very toxic to aquatic organisms

S38

In case of insufficient ventilation, wear suitable respiratory equipment.

S45

In case of accident or if you feel unwell, seek medical advice immediately

Data is from the UK HSE and Oxford University.

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Health effects based on the three most detailed studies / reports (ACGIH [Ref: 8], UK Health Protection Agency [Ref: 9] and Skrtic [Ref: 10]) are summarised below:

Concentration, ppm 0.0057 0.003 – 0.02 0.01

Exposure Patterns

Reported Effects

Chronic/community Eye and nasal symptoms, coughs, headaches and/or migraines Acute

Detectable odour

Chronic/community Neurophysiological abnormalities

0.1 – 1

Not reported

Abnormal balance with closed eyes, delayed verbal recall, impaired colour discrimination, decreased grip strength

0.2

Not reported

Detectable odour

Chronic

Nuisance due to odour

1-5

Not reported

Abnormal balance with open and closed eyes, delayed verbal recall, impaired colour discrimination, decreased grip strength, abnormal simple and choice reaction time, abnormal digit symbol and trailmaking

2–8

Chronic/community Malaise, irritability, headaches, insomnia, nausea, throat irritation, shortness of breath, eye irritation, diarrhea, and weight loss

0.25 – 0.30

10

Short term [10mins]

Eye irritation, chemical changes in blood and muscle tissue

>30

Chronic

Fatigue, paralysis of olfactory systems

50

Not reported

Eye and respiratory irritation

50 - 100

Chronic

Eye irritation ranging from painful conjunctivitis, sensitivity to light, tearing, clouding of vision to permanent scarring of the cornea

150 - 200

Not reported

Olfactory nerve paralysis

200

Not reported

Respiratory and other mucous membrane irritations

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Concentration, ppm

Exposure Patterns

Reported Effects

Not reported

Damage to organs and nervous system, depression of cellular metabolism

Chronic

Possible pulmonary oedema

Not reported

Pulmonary oedema with risk of death

Short term [30 mins]

Systemic symptoms

500 – 1000

Acute

Stimulation of respiratory system leading to rapid breathing, followed by cessation of breathing

750

Acute

Unconsciousness, death

1000

Acute

Collapse, respiratory paralysis followed by death

750 – 1000

Acute

Abrupt physical collapse, with the possibility of recovery if victim is removed from area; if not fatal respiratory paralysis

1000 – 2000

Not reported

Immediate collapse with respiratory paralysis

Acute

Death

250

320 – 530 500

5000

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Published toxicological data parameters for hydrogen sulphide as of July 2010 is summarised below. It is recommended that Group Companies consult the source in each case for further information before use.

Description

Value

Occupational Health Related TWA Limit STEL®

1 ppm over 8 hours 5 ppm for 15 minutes

QRA Use UK HSE - n, Toxic load exponent2 - Probit A parameter - Probit B parameter - SLOT value - SLOD value

4 -30.8 1.16 2 × 1012 ppm4.min 1.5 × 1013 ppm4.min

TNO Probit - n, Toxic load exponent2 - Probit A parameter - Probit B parameter

1.9 -10.87 1.0

Emergency Planning Use AEGL 1 (10 minutes) – no effect AEGL 2 (10 minutes) – disabling AEGL 3 (10 minutes) – lethal AEGL 1 (30 minutes) – no effect AEGL 2 (30 minutes) – disabling AEGL 3 (30 minutes) – lethal AEGL 1 (1 hour) – no effect AEGL 2 (1 hour) – disabling AEGL 3 (1 hour) – lethal

0.75 ppm 41 ppm 76 ppm 0.51 ppm 35 ppm 59 ppm 0.51 ppm 27 ppm 50 ppm

Note 1: Note 2:

Reference1

[8] [8]

[6]

[7]

[5] [5] [5] [5] [5] [5] [5] [5] [5]

Refer to Section 14 Refer to Section 13.1. The corresponding probit values must be used whenever this particular exponent is selected. i.e. do not use the TNO exponent with HSE probit parameters.

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