Estimation of Optimum Period of Time between Scheduled Maintenance in Iraqi Oil Refineries by using Operation Research Techniques

Operations research is a powerful mathematical method available to managers to solve their administrative problems. Some methods of operational research can be applied in field of maintenance management, in other words, applying scientific methods to finding solutions to industrial problems, including maintenance work. The objective of this study to use the probability model to estimate the optimum period of scheduled preventive maintenance to give the manager the opportunity to choose the best maintenance time with the lowest cost. Microsoft Excel was used to build a special probability model to solve this problem and perform calculations. The probabilistic model to solve this problem was carried out in Najaf Oil Refinery (NOR) as a case study instead of other Iraqi oil refineries. The three production units were used in NOR for this purpose.