OCE6 - Hydrogen sulphide

Health and Safety Executive

OCE Hydrogen sulphide

Offshore COSHH Control approach R essentials Respiratory protective equipment

This information will help offshore What this sheet covers dutyholders (owners, operators and This sheet describes good practice for work in areas where hydrogen contractors) to comply with the Control sulphide may arise. It covers the key points you need to follow to of Substances Hazardous to Health help reduce exposure to an acceptable level, as part of your COSHH Regulations 2002 (COSHH), as amended, to assessment. protect workers’ health. Hazards This guidance consolidates good control 3 Hydrogen sulphide (H2S) may be present in hydrocarbon process practice and reinforces existing knowledge systems, particularly when reservoirs begin to mature and water out. with additional information. 3 In addition to process plant, H2S may arise in well fluids, drilling muds, sewage, etc It will help you carry out COSHH 3 H2S is a very toxic, flammable gas. It is pungent (rotten egg odour) and assessments, review existing assessments, irritates the eyes, nose and throat. It rapidly destroys the sense of smell deliver training and in supervising activities and can cause unconsciousness and death. involving substances hazardous to health. 3 It is heavier than air and may accumulate in low-lying areas. 3 The workplace exposure limits (WELs), for H2S are 5 ppm (8-hour time- It is aimed at staff whose responsibilities weighted average (TWA)) and 10 ppm (15-minute TWA). include the management of substances Caution: Odour is unreliable as a means of detecting H2S. hazardous to health on offshore installations (eg occupational health Access specialists, COSHH assessors, supervisors etc). It is also useful for trade union and 3 Restrict access to areas where H2S is known or suspected. employee safety representatives. 3 Post H2S warning notices at points of access to Category 0 and Category 1 areas.

Following this guidance is not compulsory 3 Fit air direction and air movement indicators or windsocks in areas that rely on natural ventilation for H2S control. and you are free to take other action. But if you do follow this guidance, you will Equipment and procedures normally be doing enough to comply with the law. Health and safety inspectors seek Planning to secure compliance with the law and may 3 Label and colour-code plant and equipment that may contain H2S. refer to this guidance as illustrating good 3 Classify areas and decide the use of fixed/portable H2S detectors. practice. See below and Offshore Information sheet 6/2009 – see ‘Further information’. Also see essential information on the back 3 Prepare a contingency plan that covers H2S emergencies. of the sheet. 3 Mark up site plans with H2S and safe areas. Area classification n Category 0: H2S is present during normal operations, eg in vessels and confined spaces. n Category 1: H2S may be present during normal operations, eg mud tanks and shale shaker areas.

Hydrogen sulphide OCE6 Respiratory protective equipment

n Category 2: Area is normally free of H2S, but breach of containment or leaks may create risk: n Category 2A: Less than 500 ppm H2S in the process stream. n Category 2B: More than 500 ppm H2S in the process stream.

Control 3 Remove H2S through chemical treatment methods, eg H2S scavengers, use of biocides to prevent growth of sulphate reducing bacteria. 3 Isolate and depressurise enclosed systems before breaking containment. 3 Purge residues and ventilate to remove H2S. 3 Provide forced ventilation, eg on air blower where there is no through draught. 3 Respiratory protective equipment is normally required 3 Provide detection and alarms n Category 0 area: Portable/personal H S detectors 2 n Category 1 area: Fixed H S detectors and portable/personal H S 2 2 detectors for entry. n Category 2A area: Fixed hydrocarbon detectors and portable/

personal H2S detectors for breaking containment. n Category 2B area: Fixed H S detectors and portable/personal 2 detectors for breaking containment.

Emergency procedures 3 Store protective and emergency equipment in safe areas. 3 Provide positive pressure emergency breathing apparatus (BA) sets wherever there is a risk of H2S gas release. 3 Establish and train emergency rescue teams (ERT). Hold regular practices. 3 Include resuscitation of H2S victims in first aid training. 3 See Face fitting for emergency BA SPC 2000/5. Personal protective equipment (PPE) – see OCM3 3 Ensure that all items of PPE are compatible. 3 RPE will be required for work in all areas where H2S concentrations exceed the WEL.

Respiratory protective equipment (RPE) – see OCM4 3 Provide CE-marked positive pressure BA with an assigned protection factor of at least 40.

Maintenance, examination and testing Checking and maintenance 3 Before use, check the air lines for supplied-air BA. 3 Before each use, check that portable/personal gas monitors are fully charged and working properly. 3 Follow the planned maintenance regime (PMR) 3 Ensure that fixed H2S detectors and alarms are working properly and fail to the ‘alarm’ state. 3 Keep this information in your testing logbook.

Hydrogen sulphide OCE6 Respiratory protective equipment

Examination and testing – RPE Employee checklist 3 Examine and test RPE thoroughly at least monthly and for infrequently Is your portable/ used RPE at least three monthly. Replace worn parts. personal alarm fully 3 Check the airflow and air quality to air-fed RPE at least once every charged and working three months, or before use. Check in-line filters. properly? 3 Ensure that breathable air compressors take in clean air. Is your respirator working Records properly? Check it every 3 Keep records of all examinations and tests for at least five years time.

Look for signs of wear Cleaning and housekeeping and damage to 3 Clean the area after the task, or as specified in working procedures. equipment.

Personal decontamination and skin care If you find any problem, 3 Provide warm water, mild skin cleansers, nailbrushes, and soft paper, get it fixed. Don’t just fabric towels or hot air for drying. Avoid abrasive cleansers. carry on working.

Training and supervision Further information 3 Provide supervision – ensure that safe work procedures are followed. Respiratory protective 3 Explain the dangers of H2S. equipment at work: A practical 3 Supervise the use of control measures for H2S work. guide HSG53 (Third edition) 3 Training includes toolbox talks on: HSE Books 2005 n how to use the right safe working procedures; ISBN 978 0 7176 2904 6 n how to react to alarms and evacuate safely; www.hse.gov.uk/pubns/books/ n how to use RPE in particular correct donning procedures; hsg53.htm n check that it is working; and Workplace exposure limits EH40 n what to do if something goes wrong. www.hse.gov.uk/coshh/table1.pdf 3 Involve managers and supervisors in health and safety training Face fitting for emergency BA Essential information SPC 2000/05 HSE OCE0 Advice for managers Managing hydrogen sulphide OCM3 Personal protective equipment (PPE) detection offshore Offshore OCM4 Respiratory protective equipment (RPE) Information Sheet 6/2009 HSE OCM5 Emergency planning www.hse.gov.uk/offshore/ OCE14 if mercury is present infosheets/is6-2009.htm ORE1 if NORM is present. Fit testing of respiratory protective equipment facepieces OC 282/28 HSE

You can find the full Offshore COSHH essentials series at www.hse.gov.uk/coshh/index.htm

This guidance was developed by representatives from the UK offshore oil and gas industry and trade unions, with HSE.

© Crown copyright 2011 Published by the Health and Safety Executive 08/11