Chapter 3 – Process Safety Information (PSI)
In order to properly conduct a Process Hazard Analysis on a process, information needs to be gathered concerning that process.
That information is called Process Safety Information and is compiled about the process so employees can identify and understands its hazards.
This PSI information is broken down into three sections:
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Information pertaining to the hazards of the chemical.
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Information pertaining to the technology of the process.
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Information pertaining to the equipment of the process.
PSI must be compiled before conducting any Process Hazard Analysis.
Information Pertaining to the Hazards of the Chemical includes:
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Toxicity Information, such as:
Lethal Dose
Threshold Limit Value (TLV)
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Permissible Exposure Limits
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Physical Data, such as:
Boiling point
Vapor pressure
Vapor density
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Reactivity Data – how the it reacts with various other families of materials.
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Corrosivity Data – effect on containment materials.
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Thermal and Chemical Stability Data, such as:
Flammability limits
Flash point
Autoignition temperature
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Hazard Effects of Inadvertent Mixing of Different Materials
Commonly used references for the above information are:
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Safety Data Sheet (SDS)
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Threshold Limit Values and Biological Exposure Indices published by the American Conference of Governmental Industrial Hygienists (ACGIH)
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National Institute for Occupational Safety And Health (NIOSH)/OSHA Pocket Guide to Chemical Hazards
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Hazardous Chemicals Desk Reference
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American Society of Mechanical Engineers (ASME), Boiler and Pressure Vessel Code
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American National Standards Institute (ANSI), Piping Code for Process Facilities
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American Petroleum Institute (API)
Information Pertaining to the Technology of the Chemical includes:
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Block Flow Diagram – simplified diagrams showing how the major components are connected in the process.
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Process Chemistry – the nature of the intended reactions needed for the process.
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Maximum Intended Inventory – for all storage tanks, reactors, drums and other vessels of the process.
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Safe Upper/Lower Limits – operating range for example:
Pressures
Temperatures
Flow rates
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Evaluation of consequences of deviations from the safe upper/lower limits, including those affecting safety and health of employees.
Information Pertaining to the Equipment and the Chemicals includes:
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Materials of Construction – which materials were used in the construction of the process.
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Piping and Instrument Diagrams that depict information such as:
All components
All piping
Flow directions
All valves
Symbols of each instrument
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Electrical Classifications – defined by National Fire Protection Association (NFPA) with respect to its potential for causing an electrically generated fire.
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Relief System Design and Design Basis – rationale for providing safety relief valves in certain locations, the selection of the size, establishment of set points, etc.
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Ventilation System Design and Design Basis, such as:
Air flow calculations
Equipment sizing calculations
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Design Codes and Standards Employed – used to form the design basis of the process.
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Material and Energy Balances for Processes Built after May 26, 1992.
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Safety Systems such as:
Lightning protection systems
Control interlocks
Systems designed to detect toxic or flammable materials
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Equipment complies with recognized and generally good engineering practices.
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Equipment designed/constructed to codes/standards no longer in general use, employer shall determine/document that the equipment is designed, maintained, inspected, tested, and operating in a safe manner.
