Employers must complete a compilation of written process safety information before conducting any process hazard analysis required by the standard. The compilation of written process safety information, completed under the same schedule required for process hazard analyses, will help the employer and the employees involved in operating the process to identify and understand the hazards posed by those processes involving highly hazardous chemicals. Process safety information must include information on the hazards of the highly hazardous chemicals used or produced by the process, information on the technology of the process, and information on the equipment in the process.

Information on the hazards of the highly hazardous chemicals in the process shall consist of at least the following:

  • Toxicity

  • Permissible exposure limits

  • Physical data

  • Reactivity data

  • Corrosivity data

Thermal and chemical stability data, and hazardous effects of inadvertent mixing of different materials

Information on the technology of the process must include at least the following:

  • A block flow diagram or simplified process flow diagram

  • Process chemistry

  • Maximum intended inventory

  • Safe 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 employees

Where the original technical information no longer exists, such information may be developed in conjunction with the process hazard analysis in sufficient detail to support the analysis.


Information on the equipment in the process must include the following:

  • Materials of construction

  • Piping and instrument diagrams (P&lDs)

  • Electrical classification

  • Relief system design and design basis

  • Ventilation system design

  • Design codes and standards employed

  • Material and energy balances for processes built after May 26, 1992

  • Safety systems (e.g., interlocks, detection or suppression systems)

The employer shall document that equipment complies with recognized and generally accepted good engineering practices. For existing equipment designed and constructed in accordance with codes, standards, or practices that are no longer in general use, the employer shall determine and document that the equipment is designed, maintained, inspected, tested, and operated in a safe manner.

The compilation of the above described process safety information provides the basis for identifying and understanding the hazards of a process and is necessary in developing the process hazard analysis and may be necessary for complying with other provisions of PSM such as management of change and incident investigations.

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