Safety assessment through HAZOP‐LOPA‐SIL analysis implementation in the DPA demulsifier production process

Abstract In this paper, the HAZOP‐LOPA‐SIL method is implemented on a safety assessment for an O‐benzenedicarboxylic acid diallyl ester (DPA) demulsifier production process. The risk matrix and tolerable risk criterion are determined with hazard and operability (HAZOP) analysis, and the whole processing technique is divided into nine nodes and seven safety instrumented functions (SIFS). By using guide words and subsequence parameters, the deviation of each node is analyzed, and recommendations are then proposed. After determining the safety integrity level (SIL) of each SIF according to the layer of protection analysis (LOPA) method, the result shows that the SIL of the whole system is SIL1. Considering the influence of mechanical element degradation (valves) on SIL determination, gamma distribution has been adopted to analyze the gradation process. In the serviceable cycle, the minimum PFD average is larger than 0.21 in order to exceed the range of SIL 1. This means that the SIL of the SIF can effectively prevent the failure caused by valve degradation. According to software analysis, the SIL validation result of the whole safety instrument system(SIS) is SIL1.