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. 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.thumb|380x380px|Fourteen elements of OSHA's process safety management program

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.

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.

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.

Training

Training relevant to PSM must include emphasis on the specific safety and health hazards of the process, emergency operations including shutdown, and other safe work practices that apply to the employee’s job tasks. The regulation distinguishes between two types of training relevant to PSM, i.e. initial training and refresher training. Training records must be kept and maintained.

OSHA's PSM includes special provisions for contractors and their employees to emphasize the importance of everyone taking care that they do nothing to endanger those working nearby who may work for another employer. The contracting party must obtain and evaluate the contractor's safety performance and programs, inform the contracted personnel of the relevant fire, explosion, or toxic release hazards, explain to them the applicable provisions of the emergency action plan, evaluate periodically their performance in fulfilling their obligations, and maintain a contract employee injury and illness log. The contracted company must ensure that its employees have sufficient relevant training for the contracted job, ensure that its employees are instructed in the relevant site process hazards and the applicable provisions of the emergency action plan, document that they have received and understood required training, keep a record of key information about the contracted employees on the job and the activities carried out, and ensure that each contracted employee follows the safety rules of the facility. not just those directly responsible for fluid containment, according to a wider asset integrity management strategy that includes systems such as active and passive fire protection, fire and gas detection, sources of emergency power, etc.

Hot work permit

Among several safety systems of work relevant to hazardous process plants, OSHA's PSM singles out the permit-to-work for hot work as arguably the most critical for the prevention of major process safety accidents. Hot work provides ignition sources to potential flammable vapors, which can cause fires and/or explosions. The permit must document that the fire prevention and protection requirements in OSHA regulations have been implemented prior to beginning the hot work operations. It must indicate the date(s) authorized for hot work and identify the object on which hot work is to be performed. The permit must be kept on file until completion of the hot work. Changes to a process must be thoroughly evaluated to fully assess their impact on employee safety and health and to determine needed changes to operating procedures. Written procedures to manage changes (except for “replacements in kind”) to process chemicals, technology, equipment, and procedures must be established and implemented. Minimum content of the documentation is:

  • The technical basis for the change.
  • Impact of the change on safety and health.
  • Modifications to operating procedures.
  • Necessary time period for the change.
  • Authorization requirements.

Employees who operate a process and maintenance and contract employees whose job tasks will be affected by a change in the process must be informed of, and trained in, the change. Accordingly, thorough internal investigation of incidents to identify the chain of events and causes is crucial to OSHA's PSM. Investigation must be initiated as promptly as possible, not later than 48 hours following the incident. OSHA establishes requirements for the investigation team selection and the content of the investigation report, which has to conclude with a series of relevant lessons learnt in the form of recommendations. These shall be tracked and closed out accordingly. Additionally, robust emergency management helps an organization safeguard its public image in case of accidents.

Compliance audits

Similar to incident investigation, audits are an important tool an organization can use to assess whether its process safety management system is in place and it is effectively applied throughout its ranks. Emphasis is given in the regulation to the fact that trade secrets may in principle restrict circulation of key information in several ambits of process safety management, such as process safety information, compliance audits, operating procedures, process hazard analysis, incident investigation, etc. The regulation makes it compulsory for organizations to release the information to the respective parties, irrespective of whether it is protected by trade secrecy. Nothing in PSM, however, precludes the employer from requiring those persons to enter into confidentiality agreements not to disclose the information.