PHA Revalidations | Beyond Checking Boxes

Introduction | Process Hazard Analysis Revalidation

April 2025 — by Carolyn Bott, Process Safety Group Manager — In the world of industrial operations, hazards are a given — but unmanaged hazards are a risk no facility can afford. A well-executed Process Hazard Analysis (PHA) is a vital safeguard, helping teams identify potential risks and define the controls needed to mitigate them. But a PHA isn’t a one-time event. As facilities and operations evolve, so must the analysis. That’s where a PHA Revalidation comes in.

What is a PHA Revalidation?

A PHA revalidation is a systematic update of an existing PHA study to ensure that it accurately reflects current operations, risks, and safeguards. Mandated under OSHA’s Process Safety Management (PSM) standard (29 CFR 1910.119), PHA revalidations are required at least once every five years. This ensures that facilities consistently assess whether existing safeguards and Independent Protection Layers (IPLs) are still appropriate and effective.

Unlike a first-time PHA, a revalidation starts with reviewing the previous study. The team evaluates modifications — be it process design, control systems, staffing, procedures, or incident history — and determines whether those changes introduce new risks or warrant updates to the previous Process Hazard Analysis study.

It should be noted that in some cases, a facility may determine that the existing PHA is no longer a reliable baseline — perhaps because of major modifications, process redesign, or poor quality in the original study. In these situations, a full PHA redo may be the better option.

Methodologies Commonly Used in PHA Revalidations

Several risk assessment methodologies are used during PHA revalidations, depending on process complexity and organizational preference. These include:

• HAZOP (Hazard and Operability Study): A systematic, guideword-based approach for continuous and batch processes

• LOPA (Layers of Protection Analysis): A method for evaluating the effectiveness of protection layers in reducing the frequency or consequence severity of hazardous events

• What-If and Checklist Analyses: Useful for simpler systems or as supplementary tools

• HAZID (Hazard Identification Study): Often applied in the early design phase or as a high-level review

• FMEA (Failure Modes and Effects Analysis): Focuses on component-level failure scenarios

• Bowtie Analysis: Visual mapping of causal pathways and safeguards for major hazards

These methodologies are not mutually exclusive — they are often used in combination. The chosen methodology(s) should match the process and risk profile.

Regulatory Requirements and OSHA Expectations for PHA Revalidations

According to OSHA, a PHA must be revalidated at least every five years to ensure it remains consistent with the current process. The revalidation must be conducted by a team with expertise in engineering, operations, and hazard analysis methodology. The team should evaluate changes in equipment, procedures, and materials; verify that recommendations from previous PHAs have been resolved; and confirm that documentation and drawings (such as P&IDs) are current.

OSHA further clarifies that a PHA revalidation doesn’t need to start from scratch. It can build upon the previous PHA, provided the review is thorough and documented. Failing to properly revalidate — whether by missing the five-year deadline or conducting an insufficient review — can lead to citations and increased risk exposure.

Should I Revalidate Sooner Than Five Years?

While the five-year cycle is the regulatory minimum, some facilities choose or need to revalidate more frequently. Situations that may warrant earlier review include:

-          Significant process changes such as new equipment, revised control strategies, or major throughput adjustments

-          Facility expansions or new unit operations

-          Introduction of new chemicals or process conditions

-          Recurring incidents or near misses suggesting underlying hazards were missed

-          Internal audits that identify PHA gaps or non-compliance

-          Evolving industry standards or new safety guidance that impact existing risk assessments

In such cases, updating the PHA before the five-year mark can strengthen safety performance and demonstrate due diligence to regulators and insurers.

Five Common Challenges in PHA Revalidations

Executing a quality PHA revalidation takes planning, expertise, and cross-functional engagement. Below, we describe five common challenges that facilities face when conducting a Process Hazard Analysis Revalidation.

1.      Inadequate Documentation and Information Management 

A revalidation is only as good as the information available. If the previous PHA scenarios were poorly documented or if process safety information (P&IDs, chemistries, etc.) hasn’t been kept current, the team will struggle. Without complete, up-to-date data on what has changed since the last PHA, important scenarios might be overlooked, or the team may waste time reconfirming basic facts.

2.     Loss of Key Knowledge and Stakeholder Engagement

It isn’t uncommon to find that the team who performed the initial PHA has transferred, retired, or simply moved into new roles by the time of revalidation. If a PHA Reval is not documented effectively, nor involves the appropriate process experts, understanding of the process risks can be lost. This type of insufficient stakeholder engagement can result in missing insights into how the process truly operates or deviates. Every PHA relies on the collective knowledge of its team and if that’s weakened, the revalidation may miss hazards or misunderstand the adequacy of IPLs.

3.     Poor or Inconsistent Methodology Application

If your PHA revalidation isn’t executed with consistent and up-to-date methods, gaps can occur. In some cases, the prior PHA might have used a different method or risk criteria than what the company uses now, causing confusion. For example, if the initial PHA methodology was misapplied or too simplistic for the process, it can result in the need for substantial correction down the road. Ensuring a comprehensive and systematic approach is applied during revalidation is vital to avoid leaving gaps.

4.     Underestimating Time and Resources Required

PHA revalidations can be resource intensive. A common mistake is assuming a revalidation will be quick since “we’ve done this before”, and then not allocating enough time or personnel knowledgeable in the process. The result can be rushed sessions, incomplete reviews, or missing documentation. If an organization doesn’t budget adequate time (including for pre-work and team meetings), the five-year deadline can sneak up.

5.     Failure to Close Gaps from Previous PHA Recommendations

A situation that many face during a PHA revalidation is discovering that some recommendations or gaps from the last PHA were never implemented or fully resolved. Not only does this pose an ongoing risk, but it also complicates the analysis — the team might find themselves re-discussing hazards that should have been mitigated. OSHA expects that existing PHA recommendations are tracked and completed before revalidation​. If that hasn’t happened, your facility faces both compliance issues and potentially repetitive findings. This issue often stems from lack of a robust management system for PHA action items.

Anticipating and addressing these challenges early can significantly improve the quality of your PHA revalidation process.

Best Practices for an Effective PHA Revalidation

To mitigate the challenges described above, facilities should adopt several best practices for PHA revalidations:

• Prepare thoroughly: Update your process safety information, drawings, procedures, and incident history before the first team meeting. Performing this type of “mini audit” of changes and process safety performance since the last PHA will help drive the revalidation scope.

• Engage experienced facilitators: Facilitators with expertise in the methodology selected for the reval can guide the process and ensure consistency across nodes and scenarios. Ultimately, your PHA Reval team should consist of experienced operations personnel, engineers familiar with the process, and a competent facilitator. Additionally, involving members from the original PHA team and/or certified PHA leaders can benefit the effort.

• Involve stakeholders: Cross-functional support from those in operations, engineering, maintenance, and even management stakeholders who understand the process will increase your ability to maintain consistency and accuracy throughout the revalidation process.

• Verify implementation of past recommendations: A revalidation is an opportunity to check the status of all previously identified hazards. Best practice is to explicitly review how each risk scenario identified last time has been addressed. The team should verify that no known hazard has been forgotten. If some recommendations were deferred or not resolved, this is the time to reassess those risks and decide on an action. Additionally, incorporate any relevant incident learnings (from your site or industry) to enhance the prior analysis​. By looping back on past findings and new learnings, the revalidation closes gaps and solidifies your facility’s risk baseline.

• Document and track everything: Just as you review old recommendations, establish a strong process for following through on new PHA recommendations coming out of the revalidation. This includes clearly prioritizing them (e.g. using a risk matrix or LOPA results to rank urgency), assigning responsibility, and setting deadlines. Remember, OSHA requires documented resolution of PHA recommendations​ — having a tracking system not only aids safety but keeps your facility compliant.

• Consider partnering with a qualified PHA facilitator: One of the best investments for a successful PHA revalidation can be partnering with a skilled facilitator. An experienced, third-party PHA facilitator can provide a litany of benefits — including chemical and process knowledge across industries. Beyond providing expert guidance, facilitators can also serve as an objective, unbiased perspective. When considering an external PHA facilitator, look for a provider who goes beyond “checking the boxes.” Facilitators should also offer effective prioritization of risks and recommendations. Additionally, a facilitator should be able to present an actionable gap closure game plan that includes recommendations for trusted engineering solutions providers who can support resolving identified issues.  

You’ve Completed Your PHA Reval — What Next?

A successful PHA revalidation doesn’t end when the last worksheet is signed. The real value comes from implementing recommendations and closing identified gaps. At this stage, facilities should:

-          Prioritize recommendations using risk matrices or LOPA to focus efforts on high-consequence scenarios

-          Develop actionable plans for implementation, assigning ownership, and tracking progress

-          Work with a facilitator or engineering partner who can help close common recommendations such as SIS upgrades, BPCS changes, Alarm Management improvements, BMS modifications, Facility Siting enhancements, and Fire & Gas system updates.

-          Document closure, including verification of effectiveness and updates to procedures or training as needed

Without follow-through, a PHA revalidation becomes a compliance checkbox rather than a meaningful tool for reducing risk.

The Takeaway | Turn Your PHA Reval Findings into Forward Motion

Process safety isn’t static — and your PHA shouldn’t be either. Regular, well-executed PHA revalidations are essential to staying compliant with OSHA, maintaining operational continuity, and safeguarding personnel and assets.

For facilities navigating complex changes, aging infrastructure, or resource constraints, engaging with experienced PHA facilitators can bring structure, insight, and measurable outcomes to the revalidation process. When done right, PHA revalidations don’t just ensure compliance — they create a roadmap for safer, smarter operations.