Hazard overview
Hydrogen Sulfide is a colorless gas possessing the disagreeable odor associated with rotten eggs. Potential employee exposure to H2S can consist of: recycled drilling mud, water from sour crude wells, blowouts, refining operations, etc. It is occasionally encountered naturally as the result of the decay of organic waste. Sewage and swamp water, for example, typically contain dissolved hydrogen sulfide. We sometimes hear that such materials “smell like sulfur.” But elemental sulfur is an odorless solid; what is actually meant is that such materials smell like hydrogen sulfide. Some amount of hydrogen sulfide is almost always present in our atmosphere.
Health effects
Continued inhalation in an atmosphere containing hydrogen sulfide causes dizziness, the onset of a headache, eye irritations, difficulty breathing. One deep breath of pure hydrogen sulfide is fatal; breathing a concentration of 600 ppm (parts per million) by volume is fatal within 30 minutes. Since it possesses such a disagreeable odor, most people are initially aware of its presence. However, hydrogen sulfide also deadens the sense of smell rapidly. Thus individuals who remain in an atmosphere containing hydrogen sulfide become oblivious to its presence and may inhale dangerous or lethal amounts unknowingly. Low levels of exposure may cause one or more of the following systems with extended exposure.
• Skin irritation
• Eye irritation
• Fatigue
• Nausea
• Dizziness
• Irrational behavior
• Dryness in nose, throat
• Coughing
• Loss of consciousness or death
• A headache
• Loss of appetite
OSHA overview
Hydrogen Sulfide is available industrially, mainly as a liquid, in containers. It is primarily used in the chemical industry to produce other sulfur-containing compounds, but hydrogen sulfide is also used in the metallurgical industry. In the workplace, OSHA regulates the exposure of employees to hydrogen sulfide. OSHA stipulates a permissible exposure limit of 50 ppm by volume of hydrogen sulfide for no more than 10 minutes, But NIOSH allows only 10 ppm.
DOT overview
The Department of Transportation regulates Hydrogen Sulfide as a poisonous gas. Containers are labeled POISON GAS and FLAMMABLE GAS, and their transport vehicles are similarly placarded.
Permit-required confined space program
The employer will implement our confined space program when performing work in areas designated as a confined space. The permit-required confined space program will conform to the requirements of 29 CFR 1910.146.
This employer shall:
Implement the measures necessary to prevent unauthorized entry.
Identify and evaluate the hazards of permit spaces before employees enter them.
Pre-Entry requirements. Develop and implement the means, procedures, and practices necessary for safe permit space entry operations, including, but not limited to, the following:
o Specifying acceptable entry conditions.
o Isolating the permit space.
o Purging, inserting, flushing, or ventilating the permit space as necessary to eliminate or control atmospheric hazards.
o Provide pedestrian, vehicle, or other barriers as necessary to protect entrants from external hazards.
o Verify that conditions in the permit space are acceptable for entry throughout the duration of an authorized entry.
o Develop and utilize checklists based on this standard practice instruction and 29 CFR 1910.146.
Equipment requirements. Provide the following equipment at no cost to employees, maintain that equipment properly, and ensure that employees are trained in the proper use of the equipment:
Testing and monitoring equipment needed to determine if hazardous conditions exist or to verify that they do not exist.
Types of detection devices:
• Personal monitors – Portable electronic units designed to alert personnel when PEL exceeds the preset level of 20 PPM for 1910 or 10 PPM for
1926.
• Fixed monitors – In areas where H2S is present in high concentrations, a monitor system can be used to detect H2S and are designed to alert personnel when PEL exceeds the preset level of 20 PPM for 1910 or 10
PPM for 1926.
• Colorimetric tube detectors – Are generally used for screening purposes, however, used in conjunction with the proper respiratory protection they can be used to test atmosphere for safe entry or work.
Types of respiratory equipment:
• Escape units – are designed strictly for escape from H2S.
• Supplied air units – are generally used as a work unit. Such units must have a positive pressure feature and must be equipped with an escape cylinder, in case the air supply is interrupted.
• A self Contained Breathing Apparatus (SCBA) – can be used as a work unit and is the preferred standby and rescue procedure.
Ventilating equipment needed to obtain acceptable air quality entry conditions.
o Communications equipment necessary for communication between personnel involved in the entry operation.
o Personal protective equipment insofar as feasible engineering and work practice controls do not adequately protect employees.
o Lighting equipment needed to enable employees to see well enough to work safely and to exit the space quickly in an emergency.
o Barriers and shields as required to protect workers from pedestrian, and vehicular traffic.
o Ladders, needed for safe ingress and egress by authorized entrants.
o Rescue, Retrieval, and Emergency equipment needed to extract or treat injured personnel, except to the extent that the equipment and or service is provided by rescue services that are immediately available.
o Any other equipment necessary for safe entry into and rescue from permitted spaces at our facility.
o Principal equipment needed to conduct confined space operations. The below listed intrinsically safe equipment as a minimum will be maintained where required for confined space operations.
Multi-gas monitors
Ventilation equipment
Rescue tripod/davit arm and winch system
Body harnesses
Extraction cable and lanyards
Air compressors (as required)
Supplied air respirators (as required)
Air purifying respirators (as required)
SCBA equipment (as required)
Emergency escape breathing apparatus (as required)
Radio communication system (as required)
Signage (as required)
Lock-out/tag-out equipment (as required)
Intrinsically safe lighting equipment
Personal protective clothing
Hearing protection equipment
Head protection equipment
Eye protection equipment
First aid kits
Timekeeping equipment
Hand tools
Escape ladders for depths of four feet or shoulder height
Procedures for atmospheric testing
Atmospheric testing for Hydrogen Sulfide Hazard Areas is required for two distinct purposes:
Evaluation of the hazards of the work area and verification that acceptable entry conditions for entry into that area exist.
Evaluation testing. the employer will ensure that the atmosphere is analyzed using equipment of sufficient sensitivity and specificity to identify and evaluate any hazardous atmospheres that may exist or arise. Evaluation and interpretation of these data, and development of the entry procedure, will be done by, or reviewed by, a technically qualified professional (e.g., OSHA consultation service, or certified industrial hygienist, registered safety engineer, certified safety professional, certified marine engineer, etc.) based on evaluation of all serious hazards. The internal atmosphere will be tested, with a calibrated direct-reading instrument, for the following conditions in the order given:
Verification testing. The atmosphere of a work area designated as a permit space which may contain a hazardous atmosphere will be tested for residues of all contaminants identified by evaluation testing using permit specified equipment to determine that residual concentrations at the time of testing and entry are within the range of acceptable entry conditions. Results of testing (i.e., actual concentration, etc.) will be recorded on the permit in the space provided adjacent to the stipulated acceptable entry condition. The atmosphere will be verified, with a calibrated direct-reading instrument, for the following conditions in the order given:
Duration of testing. Measurement of values for each atmospheric parameter will be made for at least the minimum response time of the test instrument specified by the manufacturer.
Testing stratified atmospheres. When monitoring for entries involving a descent into atmospheres that may be stratified, the atmospheric envelope will be tested a distance of approximately 4 feet (1.22 m) in the direction of travel and to each side. If a sampling probe is used, the entrant's rate of progress will be slowed to accommodate the sampling speed and detector response. The stratified atmosphere will be tested, with a calibrated direct-reading instrument, for the following conditions in the order given:
Mechanical integrity
Maintenance programs and schedules in processes where Hydrogen Sulfide is used will be reviewed to see if there are areas where "breakdown" maintenance is used rather than an on-going mechanical integrity program. Equipment used to process, store, or handle Hydrogen Sulfide needs to be designed, constructed, installed and maintained to minimize the risk of releases of such chemicals.
Elements of a mechanical integrity program include:
o Identification and categorization of equipment and instrumentation
o Inspections and tests
o Testing and inspection frequencies
o Development of maintenance procedures
o Training of maintenance personnel
o Establishment of criteria for acceptable test results, documentation of test and inspection results, and documentation of manufacturer recommendations as to mean time to failure for equipment and instrumentation.
The first safety priority - preventing a release. The first safety priority for any process our employees are involved will be to ensure that the process is operated and maintained as designed, and to keep the chemicals contained.
The second safety priority - controlling a release. The second safety priority will be to control the release of chemicals through engineering controls such as; venting to scrubbers, flares, or to surge or overflow tanks which are designed to receive such chemicals, etc. Also included are; fixed fire protection systems, water spray, or deluge systems, monitor guns, dikes, designed drainage systems, and other systems which would control or mitigate hazardous chemicals once an unwanted release occurs.
Work operations
Work operations in which Hydrogen Sulfide may be encountered involve welding, burning, cutting, brazing, grinding, and abrasive blasting, and general pipe fitting work.
The equipment and materials used to accomplish work operations are those normally associated with sandblasting and painting operations.
Employee crew size will vary and employee job responsibilities will be that of their craft.
Specific additional responsibilities will be:
o Superintendent/General Supervisor
o Monitors procedure to ensure compliance with this work practice.
o Supervisors
Ensures that the initial determination for potential Hydrogen Sulfide or toxic exposure has been accomplished before work begins.
Supervises the safe performance of work in accordance with this and other related work practices.
Assigns jobs only to qualified employees.
Monitoring and measurement procedures
Eight Hour Time Weighted Average (TWA) Evaluations. Where possible 8hr TWAs will be taken so that the average eight-hour exposure is based on a single eight-hour sample. Air samples will be taken in the employee’s breathing zone and by qualified personnel.
Ceiling Evaluations. Where possible, measurements to determine employee ceiling exposure will be taken during periods of maximum expected airborne concentrations of Hydrogen Sulfide. Each measurement will consist of a fifteen (15) minute sample or series of consecutive samples totaling fifteen (15) minutes. Air samples will be taken in the employee’s breathing zone and by qualified personnel.
Peak And Above Ceiling Evaluations. Measurements to determine employee peak exposure will be taken during periods of maximum expected airborne concentrations of Hydrogen Sulfide. Each measurement will consist of a ten (10) minute sample or series of consecutive samples totaling ten (10) minutes. A minimum of three measurements will be taken on one work shift and the highest of all measurements taken will be assumed to be an estimate of the employee’s
exposure. Air samples will be taken in the employee’s breathing zone and by qualified personnel.
Sampling Methods. Sampling and analysis will be conducted in accordance with acceptable industrial hygiene practices. Sampling data will be maintained for the duration of employment of the affected employee plus 30 years.
Spill and leak procedures
Spill and leak procedures will largely depend on the capability and emergency procedures of the host employer. The employer will coordinate with the host employer to ensure adequate procedures are an in-place protection of all employees’ (host and contractor) and the surrounding area.
Persons not wearing protective equipment and clothing will be restricted from areas of spills or leaks until cleanup has been completed.
Emergency Containment. Hydrogen Sulfide exposure can be fatal. Only authorized and trained emergency response personnel should attempt containment. If you are not trained in the containment of Hydrogen Sulfide Gas, evacuate the area in accordance with established procedures If Hydrogen Sulfide is spilled or leaked the following steps, as a minimum should be taken.
Remove all ignition sources.
o Ventilate the area of the spill or leak to disperse the gas.
o If in gaseous form, stop the flow of gas. If the source of a leak is a cylinder and the leak cannot be stopped in place, remove the leaking cylinder to a safe place in the open air and repair the leak or allow the cylinder to empty.
o If in a liquid form allows vaporizing.
Emergency first aid procedures
In the event of an emergency, institute first aid procedures and send for first aid or medical assistance in accordance with local procedures.
Eye Exposure: Wash immediately with large amounts of water. Lifting the lower and upper lids occasionally, get medical attention as soon as possible.
Skin Exposure: Immediately flush with copious amounts of water. Remove any clothing contaminated, and flush exposed skin areas, get medical attention as soon as possible.
Respiratory Exposure: Get the victim to open, the fresh air immediately. If breathing has stopped performing CPR. Keep the victim warm and at rest. Get medical attention as soon as possible.
Rescue Considerations. Don’t become a second victim. Move the affected person from the hazardous area. If the exposed person has been overcome, initiate local emergency notification procedures. Understand the facility’s emergency rescue procedures and know the locations of rescue equipment before the need arises.
Protective clothing and personal protective equipment (PPE)
Where engineering controls, administrative controls, and job hazard analyses do not eliminate all job hazards; employees will (where appropriate) wear personal protective equipment (PPE).
These include items such as caps, hairnets, face shields, safety goggles, glasses, hearing protection, foot guards, gloves, etc. Supervisors will ensure that equipment selected will meet the following requirements:
o It will be appropriate for the particular hazard.
o It will be maintained in good condition.
o It will be properly stored when not in use, to prevent damage or loss.
o It will be kept clean, fully functional and sanitary.
Hazards associated with wear of protective clothing, PPE, personal clothing, and jewelry. Protective clothing and PPE can present additional safety hazards. Supervisors will ensure workers wear appropriate clothing and PPE. These items will be worn so as not create additional hazards.
o Personal clothing and jewelry. Personal clothing and jewelry will be monitored by the immediate supervisor. Clothing or jewelry that could become entangled in tools, equipment or machinery or of an excessively flammable nature will be prohibited.
o Documentation. PPE requirements will be documented on a “Protective Measures Determination” form and properly filed.
Tool selection, evaluation, and condition
The greatest hazards posed by tools usually result from misuse and/or improper maintenance. Tool selection sometimes is not considered a priority when arrangements are made to begin work. All employees will consider the following when selecting tools:
Is the tool correctly for the type work to be performed?
Are guards installed properly and in good condition?
Are grounding methods sufficient when working in wet conditions?
Does the tool create sparks or heat? Has this been considered when working with flammable substances?
Do impact tools such as chisels, wedges, or drift pins have mushroomed heads? The heads can shatter on impact, sending sharp fragments flying!
Are wooden handled tools loose or splintered? This can result in the heads flying off and striking the user/coworkers!
Are cutting tools sharp? Dull tools are more hazardous than sharp ones.
Is the tool used on the proper working surface? Tools used on dirty or wet working surfaces can create a multitude of hazards.
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