Process Safety Management of Highly Hazardous Chemicals is a regulation promulgated by the U.S. Occupational Safety and Health Administration (OSHA). It defines and regulates a process safety management (PSM) program for plants using, storing, manufacturing, handling or carrying out on-site movement of hazardous materials above defined amount thresholds. Companies affected by the regulation usually build a compliant process safety management system and integrate it in their safety management system. Non-U.S. companies frequently choose on a voluntary basis to use the OSHA scheme in their business. The PSM regulation was the culmination of a push for more comprehensive regulation of facilities storing and/or processing hazardous materials, which began in the wake of the 1984 Bhopal disaster. The regulation was promulgated by OSHA in 1992 in fulfilment of requirements set in the 1990 amendments to the Clean Air Act. The EPA followed suit with a similar and complementary regulation in 1996.
Compliance Any U.S. facility that stores or uses a hazardous material above thresholds defined in section (a)(1) and Appendix A must comply with the PSM regulation. For individual chemical species listed in Appendix A, threshold quantities vary from as low as 100 lb (45 kg; e.g., methyl hydrazine, phosgene) to as much as 15,000 lb (6804 kg; e.g., ammonia solutions, methyl chloride). The threshold for flammable gases and liquids (the latter defined as having a flash point below 100 °F or 37.8 °C) is 10,000 lb (4536 kg).
Usually, these facilities are also subject to another, similar regulation issued by the Environmental Protection Agency (EPA), known as the Risk Management Program (RMP) rule (Title 40 CFR Part 68). The Center for Chemical Process Safety (CCPS) of the American Institute of Chemical Engineers (AIChE) publishes guidelines for building PSM systems that comply and exceed OSHA's expectations. These include for example guidelines on process safety documentation and implementing process safety management systems.
Process Safety Management elements The Process Safety Management program is divided into 14 "elements":
Employee participation Process safety information Process hazard analysis Operating procedures Training Contractors Pre-startup safety review Mechanical integrity Hot work permit Management of change Incident investigation Emergency planning and response Compliance audits Trade secrets All the elements are interlinked and interdependent. Every element either contributes information to other elements for the completion or utilizes information from other elements in order to be completed.
Employee participation Under PSM, employers must consult with employees and their representatives on the conduct and development of process hazard analyses and on the development of the other elements of process management, and they must provide to employees and their representatives access to process hazard analyses and to all other information required to be developed by the standard. Employee participation in process safety activities and processes helps the organization build a positive climate of collaboration across management and workers, which sustains in turn a strong process safety culture.
Process safety information Process safety information (PSI) refers to key documentation for identifying and understanding the hazards posed by the plant activities involving highly hazardous chemicals. In order to be in compliance with the OSHA PSM regulation, process safety information should include information pertaining to three areas: hazardous chemicals used or produced, technology of the process, and equipment in the process.[5] Information pertaining to the material hazards (which is usually collected in dedicated Material Safety Data Sheets [MSDS]) shall consist of at least:
Toxicity information Permissible exposure limits Physical data Reactivity data Corrosivity data Thermal and chemical stability data Hazardous effects of inadvertent mixing of different materials that could foreseeably occur Information pertaining to the technology of the process shall include at least:
A block flow diagram or simplified process flow diagram Process chemistry and its properties Maximum intended inventory Safety upper and lower limits for such items as temperatures, pressures, flows or compositions An evaluation of the consequences of deviations, including those affecting the safety and health of the employees Information pertaining to the equipment in the process should include the following:
Materials of construction Piping and instrumentation diagrams (P&IDs) Electrical classification Relief system design and design basis Ventilation system design Design codes and standards employed Material and energy balances Safety system (for example interlocks, detection and suppression systems) The employer shall document that equipment complies with "recognized and generally accepted good engineering practices" (RAGAGEP).
Process hazard analysis
A process hazard analysis (PHA) (or process hazard evaluation) is an exercise for the identification of hazards of a process facility and the qualitative or semi-quantitative assessment of the associated risk. A PHA 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 materials. A PHA is directed toward analyzing potential causes and consequences of fires, explosions, releases of toxic or flammable chemicals and major spills of hazardous chemicals, and it focuses on equipment, instrumentation, utilities, human actions, and external factors that might impact the process. This element has been called "the heart of the program", as it "impacts or interfaces with all of the other elements". PHA relies on availability and completeness of process safety information; it requires employee participation in order to be effective; it may impact operating procedure through its findings and recommendations; it must be embedded in any management-of-change process and any pre-start-up safety review. There are varieties of methodologies that can be used to conduct a PHA, including checklists, Preliminary Hazard Analysis (PreHA), Hazard Identification (HAZID) reviews, What-If reviews and SWIFT, Hazard and Operability (HAZOP) studies, Failure Mode and Effect Analysis (FMEA), etc.
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