Normalization of Process Safety Metrics
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This study is aimed at exploring new process safety metrics for measuring the process safety performance in processing industries. Following a series of catastrophic incidents such as the Bhopal chemical tragedy (1984) and Phillips 66 explosion (1989), process safety became a more important subject than ever. These incidents triggered the development and promulgation of the Process Safety Management (PSM) standard in 1992. While PSM enables management to optimize their process safety programs and organizational risks, there is an emerging need to evaluate the process safety implementation across an organization through measurements. Thus, the process safety metric is applied as a powerful tool that measures safety activities, status, and performance within PSM. In this study, process safety lagging metrics were introduced to describe the contribution of process related parameters in determining the safety performance of an organization. Lagging metrics take process safety incidents as the numerator and divide it by different process-related denominators. Currently a process lagging metric (uses work hours as denominator) introduced by the Center for Chemical Process Safety (CCPS) has been used to evaluate the safety performance in processing industries. However, this lagging metric doesn't include enough process safety information. Therefore, modified denominators are proposed in this study and compared with the existing time-based denominator to validate the effectiveness and applicability of the new metrics. Each proposed metric was validated using available industry data. Statistical unitization method has converted incident rates of different ranges for the convenience of comparison. Trend line analysis was the key indication for determining the appropriateness of new metrics. Results showed that some proposed process-related metrics have the potential as alternatives, along with the time-based metric, to evaluate process safety performance within organizations.
Wang, Mengtian (2012). Normalization of Process Safety Metrics. Master's thesis, Texas A&M University. Available electronically from