Creating a safe environment in which all harmful factors are identified, evaluated, eliminated or controlled to ensure the health of people and facilities is one of the priorities of industrial management. In recent decades, the conscientious and ethical considerations of industry owners, along with legal requirements and insurance obligations, have placed attention to safety science in a special place. Numerous methods are used to increase the current processes in the gas industry, and the study of hazards and process management is one of the best methods. The use of this method in industrialized countries is a requirement. The implementation of this system is highly recommended in developing countries and is used in many oil, gas and petrochemical industries. Implementation of HAZOP system in Iranian refineries to increase the safety of systems has become one of the most important tasks that can be done in these factories and is still used in many industries related to oil, gas and petrochemicals.