Process Safety Management of Highly Hazardous Chemicals - Part 2
By Jerry Lacatena
Further to Part 1, this brief article continues highlighting Process
Safety Management (PSM) requirements to minimize the possibility of
unexpected or accidental releases of toxic, reactive, or hazardous
chemicals listed in the OSHA PSM standard 1910.119, and to prevent
potential disasters from occurring. It focuses on the elements of PSM, and
information is largely obtained from the source documentation. Refer to
OSHA 1910.119 for details. This subject is also covered under the US Clean
Air Act amendments enacted in 1990.
The basic elements that the OSHA standard requires employers to do are
- Develop/maintain written safety information identifying workplace
chemical and process hazards, equipment, and technology used in the
- Perform a workplace hazard assessment. This includes, as
appropriate, identification of potential sources of accidental
releases, identification of any previous release within the facility
that had a potential for catastrophic consequences in the workplace,
and estimation of workplace effects of releases.
- Consult with the workforce on the development and conduct of
hazard assessments and the development of chemical accident prevention
- Establish a system to respond to the workplace hazard assessment
- Periodically review the workplace hazard assessment and response
- Develop/implement written operating procedures for the process,
including startup, normal operation, shutdown, upsets, etc.
- Provide written safety/operating information for the workforce and
training in operating procedures, emphasizing hazards, and safe
- Ensure contractor staff are provided with appropriate information
- Train workforce in emergency response procedures.
- Establish a quality assurance program to ensure that initial
process-related equipment are installed as designed.
- Establish maintenance systems for critical process-related
equipment, including written procedures, training, appropriate
inspections, testing, etc., to ensure mechanical integrity.
- Conduct pre-startup safety reviews of newly installed or modified
- Establish/implement written procedures managing change to process
chemicals, technology, equipment, and facilities.
- Investigate incidents that could have resulted in a major accident
in the workplace, and communicate findings to operating personnel and
modifications made, if appropriate.
Companies must compile written safety information before conducting
process hazards analysis (PHA). This includes information on the chemical
hazards, process/technology and equipment, as described below.
Information on the hazards of the highly hazardous chemicals used in the
process typically consists of the following:
- Physical data
- Corrosivity data
- Permissible exposure limits
- Reactivity data
- Thermal and chemical stability data
Information on the technology of the process typically includes the
- Block flow diagram or simplified process flow diagram
- Process chemistry
- Maximum intended inventory
- Safe limits for such items as temperatures, pressures, flows or
- Evaluation of the consequences of deviations, including
Where the original technical information no longer exists, such
information may be developed in conjunction with the PHA in sufficient
detail to support the analysis.
Information on the equipment in the process typically includes the
- Materials of construction
- Piping and instrument diagrams (P&lDs)
- Electrical classification
- Relief system design and design basis
- Ventilation system design
- Design codes/standards employed
- Material and energy balances for processes (built after May 26,
- Safety systems (i.e., interlocks, alarms, detection or suppression
The company must document that equipment complies with recognized and
generally accepted good engineering practices. The above process safety
information provides the basis for identifying and understanding the
hazards of a process, and may be necessary for complying with other
provisions of PSM, such as management of change and incident
Additional information on this subject will follow in a subsequent