Introduction: Industrial growth, development programs and infrastructure projects, in spite of all the advantages and benefits to humans, has been considered as the source of many hazards, risks and failures. Risk assessment is the organized and systematic method to identify hazards and risk estimation for decisions ranking, in order to reduce the risk to an acceptable extent. The aim of this study was the risk assessment of Ilam gas refinery with William fine procedure. Materials and methods: executive group consisting of managers of the gas refinery departments and agencies were formed in order to identify the risks. The risks of units using the form HSE-FO-001 (0) -90 were identified and the risk assessment of them was recorded. This technique is based on the calculation and assessment of risks that including the severity of the outcome, Occurrence probability and exposure. Results: 289 risks were found in this study which 5 risks (1.73%) had level of urgency (urgent need for corrective actions), 40Risk (13.84%) had abnormal levels (need of immediate attention) and 244 Risk (84.43%) had a normal risk level(should be deleted). Conclusion: According to information obtained from the risk assessment tables, the major risks that threaten employees of Ilam gas refinery including the risks associated with working at height, inhalation of gas containing H2S and exposure to excessive noise. Therefore, the engineering measures, in order to reduce the level of risk in the refinery units, must be conducted.

واژه‌های کلیدی: Risk assessment، William fine method، Gas field، Refinery، Ilam