Modeling patterns for reliability assessment of safety instrumented systems

Safety Instrumented Systems (SIS) act as crucial safety barriers for preventing hazardous accidents in the industrial systems. It is therefore of primary importance to study their reliability, i.e. eventually to design probabilistic reliability assessment models. SIS have common behaviors such as the periodic test policies to reveal the dangerous undetected failures. These common behaviors can be captured in models via modeling patterns. By reusing modeling patterns, the modeling process can be simplified and made more efficient. In this paper, we propose a versatile set of modeling patterns implemented in AltaRica 3.0 language. We apply them to assess the reliability of SIS described in ISO technical report ISO/TR 12489. Comparisons are performed between the results obtained from AltaRica models and those reported in ISO/TR 12489. We show that the set of proposed modeling patterns can serve as an effective tool to model SIS in a modular way.