Risk assessment is one of the main components of the health, safety and the environment systems. It is a process to identify and evaluate the factors that may compromise the success of projects. This process is to determine the qualitative and quantitative risks and know the potential consequences resulting from possible accidents and normal events on people, materials, equipment and the environment. Different methods are used for risk assessment such as HAZOP , FMEA , PHA, FTA and ETA which are among the most common approaches. Fuzzy logic systems help to simplify large-scale risk management frameworks. For risks that do not have a proper quantitative probability model, a fuzzy logic system can help model the cause-and-effect relationships, assess the degree of risk exposure and rank the key risks in a consistent way, considering both the available data and experts’ opinions. Fuzzy logic represents a significant change in both the approach to and the outcome of environmental evaluations. The key advantage of fuzzy-logic methods is how they reflect the human mind in its remarkable ability to store and to process information that is consistently imprecise, uncertain, and resistant to The main objective of this study is developing a proper approach for the evaluation of HSE risks, and highlighting the potential damage to the personnel, environment, and process equipment using fuzzy logic. In this study,the importance of HSE risks was estimated according to three criteria as “Severity of effect”, “Probability of occurrence” and “Probability of delectability”. The questionnaire method was applied and expert’s knowledge of First Refinery of South Pars Gas Field was taken. The values taken in three main risk Key words : Risk Assessment, Fuzzy Logic, Refinery, South Pars
