Maintenance Strategy Based on Reliability: A Case Study of Khoy-Azarabadegan Cement Factory in Iran

After the raw materials have been transported from the mine to the plant, the limestone and shale must be crushed into smaller pieces. The pieces are dumped into a crusher, which reduce them into fragments usually no larger than 3/4 inch across. Then, the pieces are carried by conveyors to the mixing bed hall for mixing in proper proportions and prepared for fine grinding. As can be seen, all process undertaken equipment s and performance of them determined production of the plant. Thus, engineering proposed reliability analysis to identify system s behavior for achieving optimum performance. This study aimed to investigate the reliability and proposed the appropriate maintenance strategy for crushing and mixing bed hall department of the Azarabadegan Khoy cement factory. In the first step, structure of the system and limitation of different part under the title of subsystem was determined. In the second step, the data were collected, sorted for a period of 18-month, and a database of time between failure (TBF) was formed. Then failure frequency analysis of subsystems was performed. In the third step, validation of independent and identically distributed (iid) assumption was assessed by carrying out trend and serial correlation tests. According to the results tests, the model, which describes the failure behavior, was identified based on stationary or non-stationary model. For non-stationary system, the power law process (PLP) performed and in stationary systems, the best fitted distribution of the common ones in reliability analysis was used. In the fourth step, reliability and failure rate functions were calculated and plotted. Then the importance analysis was done to prioritize subsystems based on reliability and configuration of the system. Finally, maintenance strategy for 90% of practicing target reliability level (preventive or corrective) were recommended. Therefore, it is suggested that crusher, Screen and conveyer should be checked and service before 47.2, 122, and 104.6h operation.

Keywords:

Maintenance , Reliability , Time between Failures , Importance Measure , Cement Factory