Key Performance Indicators of Aging Safety Barriers in Oil and Gas Facilities

Aging of safety barriers can degrade their performance and increase risk in Oil and Gas (O&G) facilities. Condition-informed risk assessment can be used to assess the risk of a facility given the actual performance of its safety barriers and eventually prescribe maintenance activities. In this work, we propose a novel definition of Key Performance Indicators (KPIs) of safety barriers that allows accounting for their aging. When sufficient barrier failure data are available, a Q-Weibull model is used to quantify a corrective factor that multiplies the no-aging basis KPI value. When barrier failure data are scarce, which is often the case in practice, the corrective factor is quantified by an expert-based Weibull-like distribution, that anchors some or all the different stages of barrier life (such as infant and wear-out mortality phases) with the few, limited data available. The safety barrier of Design Integrity (DI), typically employed in upstream Oil and Gas (O&G) platforms, is numerically elaborated as a practical example.

Keywords: Safety barrier, Aging, Key Performance Indicator (KPI), Bathtub curve, Q-Weibull distribution, Maximum Likelihood Estimation (MLE).

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