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

Rationale

Incidents continue to occur in various industries that use highly hazardous chemicals which exhibit toxic, reactive, flammable, or even explosive properties, or may exhibit a combination of these properties. 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. This, in turn, creates the possibility of disaster. To help assure safe and healthy workplaces, OSHA has issued the Process Safety Management of Highly Hazardous Chemicals regulation which contains requirements for the management of hazards associated with processes using highly hazardous chemicals.

Definitions

Process:

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.

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.

Applicability and compliance

Any facility that stores or uses a defined "highly hazardous chemical" must comply with OSHA's Process Safety Management (PSM) regulations. (Threshold Quantity)

Guidance directive

In 1994, OSHA Directive CPL 02-02-045 provided compliance guidelines and enforcement procedures to supplement the 1992 PSM regulation.

In particular, Appendix B of Directive CPL-02-02 provides clarifications and interpretations of the PSM regulation. This appendix contains clarifications agreed to in a settlement agreement dated April 5, 1993, between OSHA, the United Steelworkers of America, the Oil, Chemical and Atomic Workers International Union, and the Building and Construction Trades Department of the AFL-CIO. The settlement agreement clarifications reflect modifications jointly and cooperatively agreed to by the above parties and by the Chemical Manufacturers Association, the American Petroleum Institute, the Dow Chemical Company, and the National Petroleum Refiners Association.

Any additional or revised clarifications and interpretations made to Directive CPL-02-02 after 1994 are to included in Appendix B of the Directive CPL-02-02,

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 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 identifying hazards in industrial facilities and quantifying their potential severity. Appendix D of the OSHA's PSM regulations endorses the use of the methods provided in that book.

References

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Related Articles

• Accidental release source terms
• Atmospheric dispersion modeling
• Hazard analysis
• Hazardous chemicals
• Process safety

Bibliography

• Trevor Kletz (1999). Hazop and Hazan, 4th Edition. Taylor & Francis. ISBN 0-85295-421-2. 
• Frank Lees (2005). Loss Prevention in the Process Industries, 3rd Edition. Elsevier. ISBN 0-7506-7555-1. 
• Trevor Kletz (1984). Cheaper Safer Plants, or Wealth and Safety at Work, 2nd Edition. I.Chem.E.. ISBN 0-85295-167-1. 
• Trevor Kletz (2001). An Engineer’s View of Human Error, 3rd Edition. I.Chem.E.. ISBN 0-85295-430-1.