PurposeThis paper aims to investigate the failure modes present in the dangerous operations and modify processes. After the identification of potential failures, prioritization will be made to rank them for quick attention and immediate correction in the operation/modification.Design/methodology/approachThe methodology utilizes the strength of hazard and operability (HAZOP) study and failure mode and effect analysis (FMEA) to identify and prioritize the hidden potential failures present in the system. Fuzzy linguistics approach has been applied to enhance the performance of the study. This study correlates HAZOP study, FMEA and fuzzy system.FindingsThis proposed technique is used to find the better ranking of the failure modes. Risk priority number and fuzzy weighted geometric mean of the risk factors are used to improve the performance of the risk evaluation. This makes the assessment easier to be carried out effectively for critically operated systems.Practical implicationsThis proposed approach could be very useful for the systematic and rational risk assessment of passive systems.Originality/valueA new decision‐making approach is used to prioritize the failure modes present in the process industry with use of a case study.