Failure Mode Reasoning in Model Based Safety Analysis

Failure Mode Reasoning (FMR) is a novel approach for analyzing failure in a Safety Instrumented System (SIS). The method uses an automatic analysis of an SIS program to calculate potential failures in parts of the SIS. In this paper we use a case study from the power industry to demonstrate how FMR can be utilized in conjunction with other model-based safety analysis methods, such as HiP-HOPS and CFT, in order to achieve comprehensive safety analysis of an SIS. In this case study, FMR covers the failure modes of SIS inputs while HiP-HOPS and CFT are used for modeling failure of other parts. The SIS program is analyzed by FMR and the results are converted and transferred to HiP-HOPS and CFT via an automated interface. The final outcome is the collective list of SIS failure modes along with their reliability measures. We present and review the results from both qualitative and quantitative perspectives.