Identification and Assessment of Human Errors in SRP Unit of Control Room of Tehran Oil Refinery Using HEIST Technique)2007(

Introduction: In line with the man’s access to new sources of energy and the development of highly sophisticated technology, human element is assigned a more critical role in operating and controlling the systems. Today in most work environments including nuclear, military and chemical industries a human error could result in a catastrophic event. It is for this reason that the identification of the human errors and prediction of necessary prevention strategies especially in highly sophisticated systems becomes a must-do. This qualitative study is aimed to identify and evaluate the human errors in control room of sulfide recovery unit of Tehran Oil Refinery.

Materials and methods: We had 13 participants in this study. With the help of the supervisor of the unit and also through   direct observation of the activities plus individual interviews, potentially dangerous jobs in terms of causing accidents were identified. The data were then analyzed by H.T.A and the results were presented in H.T.A charts. Types of possible human errors in stages of work were identified by HEIST and also considering the factors affecting the operator including the interaction with signals and controllers. Job organization and task complexity were identified. Deviation of each from normal situation was determined using clues. Information was then transferred to HEIST work sheet for the investigation of systematical and psychological causes of the human errors.

Results: Based on the analysis of the HEIST work sheets, a total of 219 errors were identified.47 of the errors were the result of the wrong performance of the procedure plus performing a wrong procedure. 32 errors were caused by not performing the method in due course, with 26 cases because of the interaction between the operator and the signals.

Conclusion: Our results showed that the selected procedures to encounter incidents during emergencies either were not carried out properly or were wrong procedures. In some cases where the procedure was right in itself, it was not performed at the right time. Lack of access to instruction manuals, good education and the right timing resulted in the errors. Errors of the interactions with signals were caused when the signals were not in service or there was a technical problem.