Hydrogen Sulfide (H2S) Conditions
Hydrogen Sulfide (H2S) gas is very corrosive and causes metals to become brittle. Therefore, employers need to take special precautions when choosing equipment when they may reasonably expect to encounter H2S. This may include appropriate H2S trimming of equipment in accordance with National Association of Corrosion Engineers (NACE) Standards. All well-drilling sites should be classified according to areas of potential and/or actual exposure to H2S. The recommendations and employee instruction will vary depending on the type of area.
No Hazard Condition
Any well that will not penetrate a known Hydrogen Sulfide formation would be categorized as a No Hazard Area. Special Hydrogen Sulfide equipment is not required.
API Condition I - Low Hazard
Work locations where atmospheric concentrations of H2S are less than 10ppm. Recommended for Area: Hydrogen Sulfide warning sign with green flag warning device present. Keep all safety equipment in adequate working order. Store the equipment in accessible locations.
API Condition II - Medium Hazard
Work locations where atmospheric concentrations of H2S are greater than 10ppm and less than 30ppm. Recommended for Area: Legible Hydrogen Sulfide warning sign with yellow flag warning device present. Keep a safe distance from dangerous locations if not working to decrease danger. Pay attention to audible and visual alarm systems. Follow the guidance of the operator representative. Keep all safety equipment in adequate working order. Store the equipment in accessible locations. An oxygen resuscitator. A properly calibrated, metered hydrogen sulfide detection instrument.
API Condition III - High Hazard
Work locations where atmospheric concentrations of H2S are greater than 30ppm. Recommended for Area: Post legible Hydrogen Sulfide warning sign with red flag warning device. Post signs 500 feet from the location on each road leading to the location, warning of the hydrogen sulfide hazard. Check all Hydrogen Sulfide safety equipment to ensure readiness before each tour change. Establish a means of communication or instruction for emergency procedures and maintain them on location, along with contact information of persons to be informed in case of emergencies. Ensure usability of two exits at each location. Do not permit employees on location without hydrogen Sulfide safety training. (Employees may be permitted on location for specific Hydrogen Sulfide training purposes that does not include general rig training.) Pay attention to audible and visual alarm systems. Store the equipment in accessible locations. Two Hydrogen Sulfide detectors should be present (one should be a properly calibrated, metered detection instrument, and the other should be a pump type with detector tubes. The maximum permissible exposure limit (PEL) is 20 ppm. Respiratory protection would be required if periodic testing indicates employee exposures to H2S at concentrations above the PEL. See OSHA Standard Respiratory Protection, [29 CFR 1910.134]). Oxygen resuscitator. Three wind socks and streamers. Two NIOSH/MSHA 30-minute, self-contained breathing apparatus for emergency escape from the contaminated area only.