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be aware!Standards for professionals,

H2S HYDROGEN SULPHIDE

“A WAY OF LIVING”

H S E W

H2S (HYDROGEN SULPHIDE)

H2S (hydrogen sulphide) can occur in process fluids in drilling, production and processing facilities during the production of oil and natural gas. H2S is extremely poisonous and harmful to the environment. Therefore always inquire if the installation where you are going to work contains H2S classi-fied areas. If you are required to enter a H2S classified area as part of your normal work you should be trained to a level of competence commen-surate with the risks involved.

SAFETY H2S - HYDROGEN SULPHIDE

The properties of H2S

• Is a colourless gas• Has a ‘rotten eggs’ odour• Can be smelled at low concentrations (from 0.02 ppm onwards)• Is heavier than air• Forms an acid when dissolved in water• Is combustible• Can form an explosive mixture with air• Is extremely toxic to bodily systems


Dangers associated with exposure to H2S vapour

• Irritates the eyes and bronchial tubes• Can cause damage to the eyes and bronchial tubes• If serious the damage can lead to death

The exposure limit for H2S is 5 ppm over an average of 8 hours.In the case of exposure, immediately call a doctor or an ambulance.



H2S conc. (ppm) (possible) consequences

> 0.02 • “rotten egg” smell 5 • exposure limit (average over 8 hours) 10 • evacuation limit 100 • numbing of the olfactory nerves in 3 to 15 minutes • stinging of eyes and throat • risk of pulmonary oedema 200 • acute numbing of olfactory nerves • stinging of eyes and throat • risk of pulmonary oedema 500 • impairment of mental abilities • loss of sense of balance • numbing of respiratory organs in 30 to 45 min. • lethal after 30 to 60 min. 700 • rapid loss of consciousness (max. 15 min.) • breathing stops • lethal after 12 to 15 min. 1000 • immediate loss of consciousness


H2S conc. (ppm) (possible) consequences

700 • rapid loss of consciousness (max. 15 min.) • breathing stops • lethal after 12 to 15 min.

1000 • immediate loss of consciousness • acute numbing of breathing • “knock down effect” • lethal within 3 min.

Definition of H2S Zones / Classified Area Requirements

H2S-0 Zone / Areas• H2S present during normal operations• Cannot be made H2S free• Warning Notices: skull-and-crossbones symbol; wording advising; area classification; entry procedures• Entry: Work Control Certificate-Permit• Protection: positive pressure self-contained breathing apparatus, or positive pressure airline breathing apparatus with independent escape air supply• All staff involved in the work should be fully trained



H2S-1 Zone / Areas• H2S may occur during normal operations• Can be made safe for working • Warning Notices: skull-and-crossbones symbol; wording advising; area classification; entry procedures• Entry: Work Control Certificate-Permit• Before entry/during work: reduce the H2S concentration to as low a level as possible by ventilation and other means• Protection: portable and personal monitoring equipment• All staff involved in the work should be fully trained



H2S-2 Zone / Areas• Normally free of H2S• Possible contamination: system malfunction, leakage, opening of an enclosed line or equipment• Warning Notices: skull-and-crossbones symbol; wording advising; area classification; entry procedures• Alarm systems present• Before entry: portable monitor (testing the atmosphere) • Protection: portable and personal monitoring equipment• All staff involved in the work should be fully trained



H2S-2 Major Zone / Areas - additional info/requirements• Releases > 500 ppm• Risk of serious irreversible health effects• Entry control system (sign-in/sign-out)

H2S-2 Minor Zone / Areas - additional info/requirements• Releases < 500 ppm• Risk of minor reversible health effects


Training and CompetenceIf entering H2S classified areas is part of your normal work you should be trained to a level of competence commensurate with the risks involved.

Before starting to work at an H2S siteYou have to• Have permission from the person responsible for the site to enter the site• Be familiar with the hazards of H2S• Have had training in H2S• Keep a tested H2S detector in the vicinity of the breathing zone• Have an escape mask/RPE if applicable• Have determined the easiest escape route for oneself


In case of an H2S alarm• Stop all work• Leave the area immediately• Put on the escape mask• Report the incident immediately• Report to the person responsible for the area• Follow further instructions

Do not attempt any rescue actions if you do not have respiratory equip-ment or when you are alone.

Shell staff has specialist training with respect to the control of H2S or to emergency response during a release.

If you have any questions or need further information, you can always contact the Shell person in charge.


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