Study of the Role of Latent Variables in the Trip Gas Sweetening unit by using Human Factor Analysis and Based on Fuzzy Hierarchy Theory: aCase Study in the Gas Refinery

Incidents are one of the most important causes of damages in an organization often occurring due to a chain of minor and trivial errors. Therefore, recognizing the pattern and root causes of the errors are an important approach in understanding and improving safety management in the industry. This study aimed to identify human errors leading to incidents in a gas refinery using human factors analysis and classification system (HFACS).Methods and Matereals: The present study for conducted for the event of stopping the production of gas extraction in the gas sweetening unit of the refinery. So, a team consisted of six senior refinery engineers, first the analysis of root causes of events with Fishbone Diagram was prepared. Then, by combining the HFACS method and FAHP theory, the probability of occurrence of each of the reasons was analyzed.

Analyzing the worksheets of 128 activities in four levels of HFACS showed, that the highest errors rate were the first level use of Use low-quality equipment (p=6.8%) and Failure to properly analyze budget for overhaul maintenance (p=6.2%), the 2nd level of the sub-group of inadequate supervision of the maintenance supervisor (p=3.59%), the 3rd subgroup of Task-related human factors (p=3.25%) and the 4th sub-category of (p=3.2%) and Inaccuracy of the contractor in completing the checklist Contractor knowledge-based error (p=2.31%) with the most probability impact in trip gas sweetening unit incident.

The results show that errors have various causes, including individual, activity, situational, and organizational errors that require careful planning and management to eliminate or reduce these errors. Increasing the training effectiveness of operators and supervision improvement respectively are the most important measures in decreasing human error-induced incidents in refinery industry maintenance.