Process Hazard
Analysis Guide

Select the Right Methodology

The methodology should match the complexity of the process:

• What-If: Best for simple processes or as a preliminary screening tool. Uses brainstorming to identify hazard scenarios
• Checklist: Effective for well-understood processes with established industry standards. Systematic but may miss novel hazards
• What-If/Checklist: Combines brainstorming creativity with checklist thoroughness. Good for moderate-complexity processes
• HAZOP: The most rigorous methodology. Systematically examines every process parameter for deviations. Best for complex or high-consequence processes
• FMEA: Focuses on equipment failure modes and their effects. Useful for mechanical systems and control systems
• Fault Tree: Works backward from an undesired event to identify contributing causes. Best for analyzing specific catastrophic scenarios

Most facilities use HAZOP for complex processes and What-If/Checklist for simpler ones. Document your rationale for methodology selection.

Assemble the PHA Team

PHA quality depends directly on team composition. OSHA requires:

• At least one member with expertise in engineering and process operations
• At least one employee with experience and knowledge specific to the process being evaluated
• A team leader trained in the PHA methodology being used

Best practice teams also include a maintenance technician familiar with the equipment, an instrument or controls engineer, and a safety professional. For complex processes, consider engaging an external PHA facilitator with methodology expertise while your internal team provides process knowledge.

Conduct the Analysis

Before starting, ensure process safety information is complete and current. During the analysis, systematically address every area OSHA requires:

• Identify hazards for each process section, node, or equipment item
• Review previous incidents (including near misses) for the process and similar processes
• Evaluate existing engineering controls (safety instrumented systems, relief devices, containment) and administrative controls (procedures, training, inspections)
• Assess consequences if controls fail
• Consider facility siting (proximity of occupied buildings, control rooms, and property lines)
• Evaluate human factors (ergonomics, alarm management, operator workload, accessibility)

Document each scenario, its causes, consequences, existing safeguards, and any recommendations for additional risk reduction.

Manage Findings and Recommendations

The PHA will generate findings and recommendations that OSHA requires you to promptly address. Establish a system to:

• Prioritize recommendations by risk level
• Assign each recommendation to a responsible person with a target completion date
• Document the employer's response to each recommendation (accept, reject with documented rationale, or modify)
• Track implementation to completion
• Communicate resolved findings and any interim protective measures to affected employees

Plan for Revalidation

OSHA requires PHAs to be updated and revalidated at least every five years from the date of the initial analysis. Revalidation involves:

• Reviewing the previous PHA to ensure it still reflects current process conditions
• Incorporating any process changes made since the last PHA
• Evaluating new incident data and industry lessons learned
• Assessing whether recommendations from the previous PHA were implemented and are effective
• Applying current PHA methodology standards and best practices

Schedule revalidation dates in your PSM compliance calendar well in advance to allow adequate preparation time.