PHA Question Library: Hazard Review Checklist

I. Process

A. Materials and Flowsheet

• What materials are hazardous (e.g., raw materials, intermediates, products, by-products, wastes)? Are any prone to form vapor clouds? Which ones are acutely or chronically toxic, flammable, combustible, or unstable?
• What are the key properties of the process materials, including physical, toxicological, reactive, combustion, and environmental properties?
• What unwanted hazardous reactions or decompositions could develop due to improper storage, abnormal process conditions, or mechanical failures?
• What data is available or should be obtained on the amount and rate of heat and gas evolution during reactions?

B. Unit Siting and Layout

• Can the unit location minimize the transportation of hazardous materials?
• What hazards does this unit pose to the public, workers in control rooms or adjacent areas from toxic releases, thermal radiation, overpressure, noise or contamination?
• Conversely, what hazards do adjacent facilities pose to personnel or equipment within the unit itself?
• What external forces (weather, natural disasters, adjacent plant releases) could impact the site and create hazards?

II. Equipment

A. Pressure and Vacuum Relief

• Is equipment designed to withstand maximum credible overpressure?
• Are emergency relief devices (relief valves, rupture disks) appropriately located and sized based on potential scenarios like utility failures or runaway reactions?
• Is the relief system designed for two-phase flow if necessary?
• Are rupture disks in series with relief valves properly monitored and maintained?

B. Piping and Valves

• Is the piping specification suitable for process conditions, considering compatibility, pressure, temperature, and cyclical conditions?
• Are there special considerations that could promote piping failure, such as flashing liquids, freezing, cryogenic conditions, or corrosion mechanisms?
• Can piping sizes or lengths be reduced to minimize hazardous material inventory?
• Are piping systems provided with adequate freeze protection and drainage capabilities?

C. Pumps

• Can pump discharge pressure exceed the design pressure of the casing or downstream equipment?
• Are pumps protected with relief valves or minimum flow bypasses?
• Can pump suction be isolated in an emergency, and are isolation valves safely accessible?
• Is leakage of process fluid into the pump motor a potential hazard?

D. Compressors

• Similar to pumps, can compressor discharge pressure exceed design limits?
• Are compressors protected by relief or recycle valves?
• Are air compressor intakes protected from contaminants, and are gas detection and ventilation safeguards in place if compressors are in enclosed buildings?

E. Reactors

• What could cause an exothermic reaction in the reactor, such as quench failure, reactant excess, contaminants, or agitation loss?
• What are the potential hazards associated with the reactor catalyst, including pyrophoric nature or toxicity?
• What hazards are associated with catalyst regeneration processes?

F. Vessels (Tanks, Drums, Towers, etc.)

• Are vessels regularly inspected for localized damage and pressure tested?
• Is pressure relief adequate for various scenarios like cooling water failure or external fire?
• Are vessel levels monitored if they are critical for process operation?
• Are contents of all storage vessels properly identified?

G. Heat Exchangers

• What are the consequences of a tube failure, including potential reactions, flashing, or corrosion?
• Is pressure relief adequate for both sides of the heat exchanger?
• What if the exchanger is exposed to external fire or blocked in conditions?
• Is the cooling water supply reliable with backup systems and spare capacity?

H. Furnaces and Boilers

• Is the firebox protected against explosions, and does the burner control system meet safety standards?
• Are proper purging procedures in place before start-up?
• Are critical safety shutoff valves and alarms configured and tested?
• Is the furnace adequately protected against tube failures with flow controls and isolation valves?

I. Instrumentation

• Have instruments critical to safety been identified with their safety functions and alarm setpoints documented?
• Has the safety function of instrumentation been integrated with process control design?
• Are instruments designed to minimize response time lag and backed up by independent systems where necessary?
• What is the effect of faulty sensors or recorders, and how are failures detected?

J. Electrical Power

• What is the area electrical classification, and are equipment and protective techniques consistent with it?
• Are electrical interlocks and shutdowns fail-safe and periodically tested?
• Are trucks and railcars properly grounded during loading/unloading?
• Are conduits sealed against flammable vapors in hazardous areas?

K. Miscellaneous

• Are special seals necessary for severe service conditions?
• Do rotating equipment have adequate integrity shutdowns (e.g., lube oil shutdown)?
• Is vibration signature routinely monitored to detect incipient failures?
• What could cause catastrophic failure of piping or equipment?

III. Operations

• What human errors could lead to catastrophic consequences, and what measures are in place to mitigate them?
• Are complete and current procedures available for all operations (normal, startups, shutdowns, emergencies)?
• Are procedures regularly reviewed and updated, involving operator feedback?
• Are procedures written clearly for all workers to understand, considering language and background?

IV. Maintenance

• Are written procedures in place and followed for hot work, confined space entry, lockout/tagout, and other critical maintenance tasks?
• Are crane and heavy equipment operations properly governed, including operator certification and equipment inspections?
• Is complete process shutdown necessary for certain maintenance tasks, and are proper isolation and blanking procedures in place?
• Are the right tools available and used, including special tools for specific tasks?

V. Personnel Safety

• Are building structures (stairways, platforms) designed and maintained to safety standards and well-lit?
• Does the control room provide a safe haven during emergencies with adequate protection and evacuation plans?
• What fire and explosion hazards are present in operating areas, and how are they mitigated (e.g., flammable materials, ignition sources)?
• What chemical hazards are present and how are they mitigated (asphyxiants, carcinogens, irritants, etc.)?

VI. Fire Protection

• What combustible mixtures can occur in equipment under normal and abnormal conditions?
• What is the inventory of flammable liquids, and is it minimized?
• Are major storage tanks located to minimize hazard to process equipment?
• Are firewalls and partitions in place to separate critical areas?
• Are critical isolation valves fire-safe and will actuators withstand fire exposure?

VII. Environmental Protection

• Are there chemicals particularly sensitive from an environmental standpoint (carcinogens, volatile toxics)?
• Have all effluent streams been defined and are they properly treated and monitored?
• Are there procedures and equipment for spill response, and is the spill response team adequately trained and equipped?
• Are there any suppression, absorption, or cleaning media that are prohibited due to incompatibility or environmental concerns?

VIII. Management and Policy Issues

• Is upper management's commitment to employee health and safety clearly communicated and believed by employees?
• Does safety have equal status with other business objectives, and how is a "safety first" approach promoted?
• Is there a policy that clearly establishes the authority to stop work if safety requirements are not met?
• Is there an audit program that regularly reviews safety compliance, involving workers in the process?
• Are there programs for identifying and helping workers with substance abuse or mental health problems?