Which source is not typically used for failure rate and Probability of Failure on Demand (PFD) data in LOPA?

In the context of Layer of Protection Analysis (LOPA), the sources used for failure rate and Probability of Failure on Demand (PFD) data predominantly aim to identify statistical information relevant to specific systems, equipment, or processes in order to inform risk assessments.

Company internal records and historical incident data are valuable because they provide real-world observations of failures and incidents that have occurred in similar contexts, thereby offering an empirical basis for estimating failure probabilities. These sources can indicate how often particular failures have occurred in the past and help in forecasting future risks.

Guidelines for Initiating Events are also relevant, as they often provide standardized metrics and benchmarks for understanding potential failure events and their frequencies based on industry norms or standards.

Weather patterns, however, are not directly related to the failure rates of equipment or systems in the context of LOPA. While weather can influence operational conditions or may contribute to risks, it does not provide specific failure rate data or directly inform PFD calculations for safety systems. Therefore, it does not serve as a credible source for the statistical analysis needed in risk assessments, making it the correct choice in this question.