Document Type : Original Article
Authors
1
Department of Occupational Health Engineering, School of Public Health, Zabol University of Medical Sciences, Zabol, Iran
2
Department of Occupational Health Engineering, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
10.22034/sumsj.2026.580970.1094
Abstract
Introduction: Hydrocarbon storage tanks are classified as critical and high-risk equipment in the oil and gas industry due to the inherent nature of the materials being processed and the specific operating conditions. Incidents such as fires, explosions, material leaks, and overflows can not only lead to significant economic losses but also result in serious environmental consequences and threats to personnel safety. Accordingly, identifying the contributing factors to the occurrence of such events and analyzing the causal relationships between them is of strategic importance. This study employs the Bow-Tie method integrated with systematic root cause analysis to conduct an integrated analysis of risk scenarios in oil tanks. Unlike previous studies that applied Bow-Tie generically, this research specifically identifies, for the first time in an Iranian oil refinery, the causal chains and performance gaps of preventive and mitigative barriers across seven concurrent fire scenarios.
Methods: In this study, the Bow-Tie method was used to systematically integrate the techniques of FTA (Fault Tree Analysis) and ETA (Event Tree Analysis). Seven critical scenarios, including pool fire, bund fire, explosion, rupture, loss of containment, leakage, and tank overflow, were selected and investigated based on field data and library studies.
Results: The Bow-Tie analysis showed that the effective contributing factors in the occurrence of the above scenarios mainly include ignition sources, corrosion phenomena in the tank body, functional failure of inlet control valves, failure of mechanical connections, improper performance of level measurement systems, failure of safety equipment (such as relief valves), operator error, incorrect maintenance activities, as well as external factors such as seismic events and deliberate sabotage. Furthermore, effective preventive and protective barriers were identified for each event.
Conclusion: The findings of this study indicate that the Bow-Tie method is capable of providing a comprehensive and structured understanding of the risks present in process units. By offering an appropriate graphical representation of weaknesses and gaps in the safety management system, it can propose engineering and managerial solutions to reduce the likelihood of initiating events and mitigate the severity of their consequences. The implementation of online monitoring systems, optimization of preventive maintenance programs, conducting continuous training courses for personnel, and updating protection systems are among the key measures aimed at enhancing the safety level and risk management of these tanks.
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