  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 a comprehensive safety analysis of SIS.
In this case study, FMR covers the analysis of SIS inputs while HiP-HOPS/CFT
models the faults of logic solver and final elements. The SIS program is
analyzed by FMR and the results are exported to HiP-HOPS/CFT via automated
interfaces. 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.
