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PT Notes

Completeness of Scenario Identification in PHA

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A fundamental issue for PHA is the completeness of scenario identification that is achieved. PHA studies should strive to identify hazard scenarios as completely as possible. Missed scenarios can equate to the occurrence of incidents.

All PHA methods, for example, the hazard and operability (HAZOP) study, depend on the efforts of a team of people to identify hazard scenarios using an analytical process involving brainstorming that is dependent on subjective judgment regarding what events may occur and their credibility. The ability of PHA teams to achieve the identification of a complete set of hazard scenarios is limited by a number of factors. They include:

  • Technical constraints posed by PHA methods and practices, e.g. the causality of scenarios
  • Human behaviors during PHA study sessions, e.g. the ability of team members to think creatively

  • Poor quality assurance and control in conducting studies, e.g. internal factors such as the competency of team members that detract from the effectiveness of studies, and external factors such as resource limitations that adversely impact PHA team performance 

The impact of these factors on the completeness of PHA studies is not widely recognized and consequently PHA studies may be seriously deficient. A recent article identifies key factors, discusses their impact on completeness, and makes recommendations on how they can best be managed:

On the completeness of scenario identification in process hazard analysis (PHA), Journal of Loss Prevention in the Process Industries, Volume 55, pages 492-499, September 2018.

The article can be accessed for free on Science Direct until September 26, 2018 by clicking on the link below. No sign up or registration is needed.


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