Process Safety Management (United States)

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Process Safety Management (PSM) is a regulation promulgated by the U.S. Occupational Safety and Health Administration (OSHA) in 1992.[1] It is intended to prevent or minimize the consequences of catastrophic releases of toxicity, reactive, flammable, or explosive "Highly Hazardous Chemicals" (HHCs) from processes.[2]

The PSM regulation intends to accomplish its goal by requiring a comprehensive management program integrating technologies, procedures, and management practices.


The primary motivation for the promulgation of the OSHA PSM regulation was to prevent the occurrence of such disasters as the one in 1984 at Bhopal, India which resulted in more than 2,000 deaths, as well as such incidents that occurred in four chemical plants within the United States of America during the period of 1989 to 1991 and which resulted in 51 deaths and 181 injured. While these incidents were highly publicized and drew national attention, many other less publicized hazardous chemical releases also occurred.[3]

Incidents still continue to occur in various industries that use highly hazardous chemicals. Regardless of the industry that uses these highly hazardous chemicals, there is a potential for an accidental release any time they are not properly controlled. To help assure safe and healthy workplaces, OSHA issued the PSM regulation which contains requirements for the management and control of the dangers associated with processes using highly hazardous chemicals.[4]



Any activity or combination of activities including any use, storage, manufacturing, handling or the on-site movement of Highly Hazardous Chemicals (HHCs). A process includes any separate vessels or any group of interconnected vessels which could be involved in a potential release of a Highly Hazardous Chemical.


The buildings, containers or equipment which contain a process.

Highly Hazardous Chemical:

Any substance having toxic, reactive, flammable, or explosive properties. A list of 137 such substances is included in Appendix B of the PSM regulation.

Threshold quantity:

The threshold quantity (TQ) of a HHC is that quantity at or above which the HHC has a potential for a catastrophic release. The list of HHCs in Appendix B of the PSM regulation includes the TQ of each listed HHC.

Catastrophic release:

A major uncontrolled release, fire, or explosion, involving one or more HHCs, that presents a serious danger to employees in the workplace.

Process hazard analysis:

A process hazard analysis (PHA) is an organized and systematic assessment of the potential hazards associated with an industrial process. It provides information intended to assist managers and employees in making decisions for improving safety and reducing the consequences of unwanted or unplanned releases of hazardous chemicals.[5]

Applicability and compliance

The PSM regulation applies to a any process facility which contains a threshold quantity or greater amount of a toxic or reactive HHC as specified in Appendix A of the regulation. It also applies to any facility containing 10,000 pounds or greater amounts of flammable liquids and gases and to the process activity of manufacturing explosives and pyrotechnics.

The regulation specifically exempts the following facilities from the PSM requirements:

  • Retail facilities
  • Oil or gas well drilling or servicing facilities
  • Normally unoccupied remote facilities.

Summary of requirements

The PSM regulation includes the following requirements:[2]

Process safety information: Develop a compilation of written process safety information including hazard information on HHCs as well as technology and equipment information on the applicable processes.

Employee involvement: In consultation with the employees, develop a written plan of action regarding employee participation in the conduct and development of process hazard analyses and on the development of other elements of process safety management.

Process hazard analysis: Process hazard analyses (PHAs) must be conducted as soon as possible for each applicable process. PHAs must be updated and revalidated at least every five years and be retained for the life of the process.

Operating procedures: Must develop clear and written instructions for safely conducting activities involving the applicable processes.

Employee training: Employees operating a covered process must be trained in the operating procedures and the training must emphasize specific safety and health hazards, emergency operations and safe work practices. Refresher training is required at least every three years.

Pre-startup safety review: Mandates a safety review for new process facilities and for significantly modified existing facilities to confirm that the construction and equipment are in accordance with design specifications; to assure that adequate safety, operating, maintenance and emergency procedures are in place; and to assure process operator training has been completed. Also, for new facilities, the PHA must be performed and recommendations resolved and implemented before startup.

Management of change: Must establish and implement written procedures to manage changes (except "replacements in kind") to applicable process facilities. Employees must be trained on the changes prior to start-up. Process safety information and operating procedures must be updated as necessary.

Incident investigation: Requires an investigation as soon as possible (but no later than 48 hours after) of incidents which resulted or could reasonably have resulted in catastrophic releases of hazardous chemicals. A written investigation report must be developed and retained for at least five years.

Emergency planning and response: Requires the development and implementation of an emergency action plan for handling releases.

Compliance audits: Requires certification that compliance with process safety requirements has been evaluated at least every three years. Also requires prompt response to any findings in the audit and documentation that deficiencies were corrected. The two most recent audit reports must be retained.

Similar regulation by U.S. Environmental Protection Agency

The U.S. Environmental Protection Agency‎ (EPA) has a Risk Management Program (RMP) regulation (Title 40 CFR Part 68) that is fairly similar to the OSHA's PSM regulation. The EPA has published a model RMP plan for an ammonia refrigeration facility[6] which provides excellent guidance on how to comply with either OSHA's PSM regulations or the EPA's RMP regulations.

The Center for Chemical Process Safety (CCPS) of the American Institute of Chemical Engineers (AIChE) has published a widely used book that explains various methods for conducting process hazard analyses (including methodology for a Hazard and Operability Study) in industrial facilities and quantifying their potential severity.[5] Appendix D of the OSHA's PSM regulations endorses the use of the methods provided in that book.

Other nations

For more information, see: Process safety.

Other nations in Europe, Asia and elsewhere have occupational health and safety entities and some have developed process safety guidance and/or regulations.[7][8][9][10][11]