Combining the Bow-tie model and EFMEA method for environmental risk assessment in the petrochemical industry

The petrochemical industry is one of the most important economic resources and producers of materials needed by other industries on a global and regional scale. Although the petrochemical industry has many advantages, it is the source of hazards and adverse effects in various environmental sectors. This paper aims to evaluate the environmental risks of the ammonia and urea production process. For this purpose, the air quality, noise, and water quality parameters were investigated. Then the environmental aspects of the ammonia and urea units were identified through the field visit, review of documentation, and interview with the project technical experts using the Delphi Questionnaire. The environmental aspects were assessed using the Environmental Failure Mode and Effects Analysis (EFMEA) method. Next, the Bow-tie method was used to analyze the cause of occurrence and risk management. Analysis and assessing the aspects indicated that the highest frequency of pollution is related to air pollution (35%) and water pollution (29%). Among the 24 environmental aspects, the highest risk priority number of 100 was related to CO2 emission from the disposal tower. The second priority was the emission of combustible pollutant gases into the environment. Using the Bow-tie method in risk management identifies the main event and shows the causes and consequences of an accident in an understandable way. Therefore, the combined approach of Bow-tie and EFMEA is an appropriate method for risk assessment in the petrochemical industry.