RISK ASSESSMENT IN A SWEETENING UNIT IN AN IRANIAN GAS REFINERY

The risks of process hazards and equipment failures were calculated in a gas refinery – sweetening unit. The process hazards were identified by Hazard and operability stundy (HAZOP) and the component’s failures of major equipments were assessed by Failure mode and Effect Analysis (FMEA). Totally 68 hazards were identified and their risks were calculated. The highest risk (60) was belonged to the reduction of gas temperature before entering to the refinery and failure of DEA cooling system at the final node (DE). The failures of P-6 pump, F.C.V.4 valve, L.C.V.2 and F.C.V.12 (all in the same node) and reduction of gas temperature in nodes AB, BC and CD had the lowest calculated risk (12). Comparing with the acceptable level of risk in the refinery which was 200, all of the identified hazards risk were very low therefore did not need any appropriate measure of risk reduction to be proposed. For overcoming the fact that both HAZOP and FMEA techniques, instead of being performed by a team was accomplished by both of us, we used the consultations given us by the experienced exploitation engineers of under study unit. This consultation was also very useful in fulfilling deficiencies of existing record keeping system. Performing the protective maintenance and preparing a precise timing program for P.M was given as a main proposal for risk reduction by decreasing the probability of occurrence.