Anhydrous ammonia

Scope

OSHA’s standard on anhydrous ammonia applies to the design, construction, location, installation, and operation of anhydrous ammonia systems including refrigerated ammonia storage systems. This standard does not apply to:

• Ammonia manufacturing plants.
• Refrigeration plants where ammonia is used solely as a refrigerant.

Regulatory citations

• 29 CFR 1910.111 — Storage and handling of anhydrous ammonia.
• Related regulation: 29 CFR 1910.119 — Process safety management of highly hazardous chemicals.
• Related regulation: 29 CFR 1910.120 — Hazardous waste operations and emergency response (HAZWOPER).

Key definitions

• Appurtenances: All devices such as pumps, compressors, safety relief devices, liquid-level gaging devices, valves and pressure gauges.
• Cylinder: A container of 1,000 pounds of water capacity or less constructed in accordance with Department of Transportation specifications.
• Code: The Boiler and Pressure Vessel Code, Section VIII, Unfired Pressure Vessels of the American Society of Mechanical Engineers (ASME) - 1968.
• Container: Includes all vessels, tanks, cylinders, or spheres used for transportation, storage, or application of anhydrous ammonia.
• DOT: U.S. Department of Transportation. 1910.111(a)(2)(vi)
• Design pressure: Identical to the term “Maximum Allowable Working Pressure” used in the Code.
• Farm vehicle (implement of husbandry): A vehicle for use on a farm on which is mounted a container of not over 1,200 gallons water capacity.
• Filling density: The percent ratio of the weight of the gas in a container to the weight of water at 60 deg. F. that the container will hold.
• Gas: Anhydrous ammonia in either the gaseous or liquefied state.
• Gas masks: Gas masks must be approved by the National Institute for Occupational Safety and Health (NIOSH) under 42 CFR part 84 for use with anhydrous ammonia.
• Capacity: Total volume of the container in standard U.S. gallons.
• DOT specifications: Regulations of the Department of Transportation published in 49 CFR Chapter I.
• Threshold quantity for Process Safety Management: 10,000 pounds in a process, as listed in 1910.119 Appendix A.

Summary of requirements

Employers must:

• Determine if the anhydrous ammonia system contains a covered process for OSHA’s PSM standard, 1910.119. If the ammonia process, including those for ammonia refrigeration, has 10,000 pounds or more in a process, as defined, then 1910.119 applies.
• Follow the storage, use, and transfer requirements of 1910.111, as applicable.
• Provide appropriate PPE for all workers exposed to anhydrous ammonia.
• Implement an emergency response plan.