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PT Notes

Pre-work and Pre-completion for PHA

PT Notes is a series of topical technical notes provided periodically by Primatech for your benefit. Please feel free to provide feedback.

Pre-work in preparation for process hazard analysis (PHA) is vital for an efficient study. PHA studies are often time consuming and team members can suffer from fatigue which interferes with their ability to perform effective studies. Consequently, everything must be done to ensure studies are conducted efficiently. In particular, team leaders must ensure that suitable preparations are made before PHA teams convene to conduct a study. Pre-work consists of planning the study, collecting information, developing session aids and addressing logistics.

Some practitioners also make entries in the PHA worksheets in advance of team sessions in a effort to reduce the time and effort required for PHA, but pre-completion of PHA worksheets may detract from the quality of the study and also may violate regulatory requirements.

The US Occupational Safety and Health Administration (OSHA) has provided interpretations of OSHA's process safety management (PSM) standard that address this issue. From OSHA's perspective, defining hazard scenarios and developing recommendations to address them must be done by a PHA team. Thus, PHA approaches in which the team leader defines node intentions, and selects parameters and/or deviations to be considered by the team in advance of the PHA study presumably is not acceptable. However, that probably does not mean the team itself cannot start with pre-completed worksheets so long as the worksheets were developed by a team that meets the requirements of the PSM standard such as for similar process sections, similar steps in a batch process, similar processes, and in PHA revision revalidations.

From a technical perspective, it is not sensible for even a highly experienced team leader to pre-complete PHA worksheets in advance of a PHA study. Although such leaders may be able to identify many of the scenarios for the process, it is unlikely they will be as complete as for a study performed by a team for several reasons. First, every process has its idiosyncrasies which are only known to the people responsible for it. Moreover, it is unlikely that any one person knows all the idiosyncrasies. Second, brainstorming is a key aspect of PHA to flush out situations that no one has yet imagined. A single person cannot brainstorm by themselves. Third, team leaders should not have any vested interests in the process in order to avoid mindsets and bias. Consequently, such team leaders will not have the intimate process knowledge needed to identify scenarios thoroughly. Conversely, if they do have such knowledge, unrecognized mindsets and biases will impair their ability to identify scenarios. Fourth, for most modern processes, the volume of information that must be processed to perform a PHA is beyond the capability of most individuals. Fifth, when presented with a PHA that has been fully or partially completed prior to initiation of the PHA, team members are less likely to give serious consideration to searching for additional scenarios. Many team members will be inclined to accept the worksheets at face value, or with token changes, as they believe they were completed by an experienced PHA practitioner. Even with team members who are motivated to review the pre-completed worksheets critically, it can be difficult for them to do so, either because of peer pressure from other team members who want to move on and conclude the PHA quickly, or because effective team brainstorming is inhibited by the existing entries in the pre-completed worksheets.

Thus, a clear distinction must be made between pre-work, which is highly desirable, and pre-completion of PHA worksheets, which can be highly undesirable. Pre-work is vital for a smooth-running and high-quality study. Pre-completion of worksheets may result in a lower quality PHA and may violate regulatory requirements. Use of pre-completed worksheets that have been prepared by a team can be technically acceptable and may meet regulatory requirements in some cases. However, care must be taken to ensure the team gives serious consideration to tailoring them for the process being studied.

For more information, you can contact Primatech or consult the article:

Prework and Precompletion of Worksheets for Process Hazard Analysis, by Paul Baybutt, Process Safety Progress, Volume 31, Issue 3, Pages 275–278, September, 2012


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