سیستم مجوز کار

Permit-to-work system (PTW) system is a documented system to control the activities with inherent risks and probability of accident occurrence. To inform the performance and efficiency of a system, it must be periodically monitored and evaluated, and the permit to work system is no exception of this principle. The aim of the present study was to design and develop software for evaluating the performance of the PTW system.

This study included two main stages. At the first stage, based on the literature review and interview to the academic and industrial experts, the PTW questionnaire for evaluating the performance was created. The second stage involved the design and implementation of an initial version of a software and the investigation of its usability. Designing the software was performed using system development life cycle (SDLC). The usability of this software was evaluated by Think -Aloud method. Finally, the users’ satisfaction was measured using the Questionnaire for User Interface Satisfaction (QUIS) questionnaire.

Based on the results of the QUIS questionnaire, the overall satisfaction of the designed software was 7.71 in a nine-point scale. The scores of the software performance, display and user interface features, software terminology and information, learning, and overall system capabilities were obtained as 7.58, 7.37, 7.75, 8.11, and 7.74, respectively. Also, the outputs of the excel and SPSS software were in accordance with those of designed software, which show the reliability of the outputs of the designed software.

The designed software facilitate the proper and systematic analysis and it is flexible to evaluate the PTW system and represent types of reports in predefined structures that can be a useful tool in the process industries such as oil and petrochemical refineries and other similar industries.

Permit to work system  is a formal, documented and written system that aim to control risk of occupations that are considered potentially dangerous. The porpuse of this study was to identify and prioritize the criteria affecting the performance of the permit to work systeam  in an oil refinery.

The present study was designed and implemented in three steps. In the first step, by reviewing previous studies and conducting interviews with experts, the perimarly criteria were identified. In the second step, fuzzy delphi methode was used for determine the final criteria , in this step  opinions of 25 experts on the perimarly criteria were collected and combained . Finally,  fuzzy hierarchical analysis method was used in order to weight and prioritize the identified criteria.

result of Fuzzy Delphi  methode was showed that six criteria,  risk identification and risk assessment, training and competence of individuals, preventive actions , communication, responsibility and coordination as criteria affecting the performance of the permit to work systeam . Prioritization of criteria using fuzzy hierarchical analysis showed that the criterion of responsibility )final weight 0.191( and coordination and communication criteria )final weight 0.134( have the highest and lowest importance among the identification criteria.

In this study, a model of decision making based on Delphi methods and fuzzy hierarchical analysis was introduced to identify the factors affecting the performance of the  permit to work system in an oil refinery.