en Occupational Health Original Article <p style="text-align: justify;"><span style="font-size:12px;"><span style="font-family:Arial;"><a name="OLE_LINK25"><strong>Background: </strong></a>Risk assessment is an important tool for reducing casualties and financial damage in the oil and gas industry. This research aimed to identify and evaluate process hazards in the petrochemical industry in 2016.<br> <strong>Material and Methods: </strong>In this case study, a team was organized and briefed on the process. Besides, hazard identification was performed using the Hazard and Operability Study. Next, causes were analyzed using the Fault Tree Analysis and occurrence probability of top events. Finally, events and subevents were ranked. The minimum cut sets were determined using Boolean algebra.<br> <strong>Results:</strong> A total of 77 events were identified. Accordingly, unacceptable, tolerable, and acceptable risk levels were 41, 31, and 5 events, respectively. Fire was the most unacceptable risk level, with the final events of &quot;human errors in correct gasket installation on the flange surface&quot; and &quot;flange defects&quot; having had the shares of 51.2 and 21.55%, respectively.<br> <strong>Conclusion:</strong> The combination of the two HAZOP and FTA techniques is useful in process industries in which incomplete performance of the system and control systems is the most effective factor in the potential occurrence of fire. Human errors and flange defects are the two main factors in this event, so occupational safety and health must be improved in this system. Thus, due to complex interactions between humans, machines, materials, and the environment in systems, such as the petrochemical industry, which lead to uncertainties in safety results of the process, risk assessment is recommended to be performed periodically using different techniques.</span></span></p> Safety,Chemical Hazard Release,Chemical Safety,Safety Management, 105 112 http://johe.rums.ac.ir/browse.php?a_code=A-10-382-2&slc_lang=en&sid=1 Marzieh Kosari : s.mahdavi@modares.ac.ir 22400319475328460011170 22400319475328460011170 No BSc in Occupational Health, Dept. of Occupational Health Engineering, School of Health, Lorestan University of Medical Sciences, Khorramabad, Iran. Lorestan University of Medical Sciences Sakineh Mahdavi : s.mahdavi@modares.ac.ir 22400319475328460011171 22400319475328460011171 No 2. Faculty Instructor, Dept. of Occupational Health Engineering, School of Health, Lorestan University of Medical Sciences, Khorramabad, Iran; Ph.D Student in Occupational Health, Dept. of Occupational Health Engineering, Faculty of Medical Sciences, Trabiat Modares University, Tehran, Iran. Lorestan University of Medical Sciences vida zaroushani v.zaroushani@qums.ac.ir 22400319475328460011172 22400319475328460011172 Yes Assistant Prof., Social Determinants of Health Research Center, Dept. of Occupational Health Engineering, Faculty of Health, Qazvin University of Medical Sciences, Qazvin, Iran. Qazvin University of Medical Sciences Tahereh Dehghani : s.mahdavi@modares.ac.ir 22400319475328460011173 22400319475328460011173 No BSc in Occupational Health, Dept. of Occupational Health Engineering, School of Health, Lorestan University of Medical Sciences, Khorramabad, Iran. Lorestan University of Medical Sciences Zahra Naghavi Konjin : s.mahdavi@modares.ac.ir 22400319475328460011174 22400319475328460011174 No Assistant Prof., Dept. of Occupational Health Engineering, Faculty of Public Health, Mazandaran University of Medical Sciences, Sari, Iran. Mazandaran University of Medical Sciences