6. Conclusion and future research directions
The major objective of this research was to propose an FANP technique to choose the best maintenance policy of an acid manufacturing company. In this research, four maintenance strategies of CM, TBM, CBM and SM were investigated to be considered for seven equipment of a real-case study. The next considered factor was the real nature of decision makers who prefer fuzzy numbers instead of exact values. Therefore, Chang’s extended analysis was used to deal with fuzzy data and analyze the fuzzy decision matrices. The developed technique was used to a sulfuric acid production plant and the proper maintenance policy was found for all seven equipment of this company. According to the results, the CBM policy is suitable for high-risk (cooling tower) and high added value equipment (absorption tower). Furthermore, TBM is selected for boiler and converters while SM is selected for molten sulfur ponds. Finally, high-cost, low-risk and low added value equipment (sulfur fuel furnace and heat exchanger) are more appropriate to use CM policy. However, although the proposed approach was applied in a sulfuric acid production plant, it should be noted that the statement of “one particular maintenance policy is best suited to a specific industry” might not be a correct and general rule. In other words, the best fit policy is a function of many factors including the condition of equipment, regulations, operators and decision-makers’ comments. As a direction for future research, one may investigate more maintenance policies with more criteria to be fit with different equipment of companies. In addition, the maintenance policy can be investigated with regard to desired functionality and consequence of failures.
