Chemical processes can involve flammable liquids, combustible dusts, toxic gases, reactive chemicals, high pressures, and elevated temperatures. Before those hazards lead to an incident, employers need a systematic way to identify what could go wrong and evaluate the safeguards already in place.
A process hazard analysis (PHA) is one of the primary tools used for that purpose. This guide explains what a process hazard analysis is, when OSHA requires one, common PHA methods, and how often a process hazard analysis must be updated.
What is a Process Hazard Analysis?
A process hazard analysis (PHA) is a structured review of an industrial process that identifies potential hazards, evaluates how incidents could occur, and determines if existing safeguards reduce risk.
Unlike a routine workplace inspection, a PHA focuses on the process itself. The team examines equipment, operating procedures, instrumentation, controls, maintenance practices, human factors, and potential equipment failures to identify conditions that could lead to a fire, explosion, toxic release, or other process safety incident.
Which facilities need a process hazard analysis?
Not every employer is required to perform a PHA.
Process hazard analyses are primarily associated with OSHA’s Process Safety Management (PSM) standard (29 CFR 1910.119), which applies to facilities that handle specified quantities of highly hazardous chemicals.
Industries commonly performing PHAs include:
- Chemical manufacturing
- Petrochemical and refining
- Oil and gas processing
- Industrial gas facilities
- Pulp and paper
- Food and beverage processing using ammonia refrigeration
- Pharmaceutical manufacturing
- Specialty chemical production
Many companies also perform PHAs voluntarily when introducing new processes, expanding facilities, or managing higher-risk operations, even when OSHA does not specifically require one.
If you’re unsure whether your facility requires a process hazard analysis or you’re preparing for a PSM review, contact our third-party safety consulting firm. Safety by Design can evaluate your operations and help you meet OSHA requirements.
What does a process hazard analysis evaluate?
Every process is different, but most PHAs examine questions such as:
- What could go wrong?
- What events could trigger a release or failure?
- How severe could the consequences be?
- What safeguards already exist?
- Are additional controls recommended?
The review often includes:
- Equipment failures
- Instrument or control system failures
- Human error
- Utility failures
- Loss of containment
- Fire and explosion scenarios
- Toxic releases
- Emergency response capabilities
- Previous incidents or near misses
PHAs are typically completed by a multidisciplinary team that includes operations, engineering, maintenance, and safety personnel. Different perspectives often uncover hazards that one department might miss.
For example, a PHA may identify that the loss of cooling water could allow a reactor to overheat, increasing pressure inside the vessel. The review would evaluate existing safeguards, identify additional controls if needed, and document recommendations to reduce the risk of an incident.
Common Process Hazard Analysis Methods
There isn’t a single process hazard analysis methodology for every operation. OSHA recognizes several accepted approaches, and the selected method depends on the complexity of the process.
1. HAZOP (Hazard and Operability Study)
HAZOP is one of the most commonly used PHA methods for continuous processes. The team reviews each portion of the process using guide words such as No, More, Less, and Reverse to identify deviations from normal operating conditions.
2. What-If Analysis
A What-If analysis asks practical questions, for example:
- What if cooling water is lost?
- What if the wrong chemical is added?
- What if a valve fails closed?
3. Checklist Analysis
Checklist reviews compare existing operations against established safety practices, industry standards, and regulatory requirements. They are often used alongside other PHA methods rather than by themselves.
4. Failure Modes and Effects Analysis (FMEA)
FMEA evaluates individual equipment components, identifies how they might fail, and considers how those failures could affect the overall process.
How Often Must A Process Hazard Analysis Be Updated?
OSHA requires employers to revalidate each process hazard analysis at least once every 5 years under the Process Safety Management standard.
The purpose of revalidation is to confirm that the original PHA remains accurate and that previous recommendations have been completed or are still appropriate.
Revalidation often builds on the previous PHA instead of starting over. The team typically reviews:
- Equipment modifications
- Process changes
- Updated operating procedures
- Incident investigations
- Near misses
- Current industry guidance
- Previous PHA recommendations
Many facilities also review portions of a PHA before the five-year deadline when changes occur through their Management of Change (MOC) process.
What can trigger a PHA review before 5 years?
Some events call for reviewing the PHA before the required 5-year revalidation.
Examples:
- Installing new equipment
- Changing operating conditions
- Introducing new chemicals
- Expanding production capacity
- Completing major maintenance projects
- Investigating a process incident
- Identifying recurring operational problems
Remember: Process Hazard Analysis is part of a larger safety program.
Completing a PHA is not the end of the process! The findings should be incorporated into day-to-day operations.
Its findings often lead to updates in operating procedures, employee training, mechanical integrity programs, emergency response planning, and Management of Change procedures. As facilities change, those parts of the safety program should also be reviewed so they continue to reflect current operations.
Keep Your Process Safety Program Moving Forward with Safety by Design
A process hazard analysis is one part of maintaining OSHA compliance and reducing risk throughout your facility. Safety by Design works with employers to identify hazards, review existing safety programs, and develop practical solutions for their operations.
If you need assistance with process hazard analyses, safety compliance consulting, risk assessments, written safety programs, OSHA safety training, or workplace safety audits, contact Safety by Design!
Thank you for visiting our website! We appreciate your interest in workplace safety. Please note that Safety by Design is not affiliated with OSHA. However, we can assist you with the following OSHA-related services:
- OSHA Mock Inspection
- OSHA Training
- Facilitate OSHA Inspections and Citations
If you need to file a complaint with OSHA, please call 800-321-6742 (OSHA) or visit this page for other methods to contact them.
