This report addresses the failure modes of compressor stations as key facilities of gas transmission networks. This is done by finding possible failure causes, establishing a taxonomy and identifying possible effects. Given the interest of this study to analyse and identify potential critical facilities in gas transmission networks, and their possible impact on energy security, loss of capacity (partial or total) has been identified as the effect of interest of the different failures. Probabilistic results provided are unavailability, expected number of failures per year, downtime and average downtime.JRC.C.3-Energy Security, Distribution and Market