Safeguard Your Safety Review

Assumption gaps can undermine a process hazard analysis.

By G.C. Shah, Mustang Engineers

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Safety management systems. Companies differ widely in the structure and implementation of their safety management systems. It's worth verifying that management systems suffice to prevent unsafe incidents as a result of the project. Include a brief review of the company's safety management system as part of a PHA. This review should confirm that the safety management system is robust enough to ensure safe operation while the project is being implemented and after project systems are put in operation.

Risk management matrix. PHA studies often rely on this semi-quantitative method that assigns risk based on likelihood and consequence of a hazard. The criteria for determining likelihood and consequence vary widely among companies and among industries. For instance, offshore oil/gas exploration uses different criteria than refining in determining consequence (severity) of an incident. The PHA facilitator should review the existing risk matrix to verify that a consistent system of ranking risk is followed.

Consider the following steps to minimize misunderstanding:

  • Clearly define and communicate to management the scope of your PHA.
  • Prior to starting the PHA, familiarize yourself with the organization's safety management systems. Ensure they can accommodate project modifications safely.
  • Understand the terminology of the organization and technology as far as equipment and procedures of the project are concerned.
  • Make certain the PHA team comprehends your terminology.
  • Pose questions to the PHA team in a clear manner. Confirm that the team understands the intention of questions. Include examples, where appropriate, with your questions. For instance, in terms of double-block-and-bleed, you might clarify what you mean by the term "blocking." Let the PHA team elaborate on their answers.
  • Before beginning a PHA, review past unsafe incidents at the project site.
  • Consider a system's approach and lifecycle safety to ensure safety is maintained throughout the life of the project.
  • When preparing the PHA report, avoid arcane technical jargon. If you must use jargon, clearly explain the meaning of the terms. A layperson should be able to understand the report and implement its recommendations in their entirety.
  • As a general rule, to minimize assumption gaps select PHA facilitators with plant or operational experience as well as good communication and diplomatic skills.

G.C. SHAH, PE, is a safety, environmental and industrial hygiene professional at Mustang Engineers, Houston. E-mail him at

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