Optimal Policy of Condition-based Maintenance Considering Probabilistic Logistic Times and Environmental Contamination Issues

This article proposes a preventive maintenance policy for equipment that - by their very nature - can cause some forms of contamination and destruction in the environment. The purpose is to reduce overhead costs related to environmental degradation and pollution as well as other costs (e.g., inspection and replacement) by minimizing the function of the average total cost. The condition of equipment should be determined through inspection, and its operating cycle just ends in the event of a failure or precautionary repair. Maintenance services include complete repair or replacement. However, equipment conditions can cause environmental pollution, as the variables for such monitoring go beyond warning limit. After an item has been inspected in unfavorable operating conditions, complete preventive maintenance tasks should be included, in which preparation times and logistics are random variables. A mathematical model and a genetic algorithm are developed to find the optimal inspection strategy for the defined sets of parameters. Moreover, a numerical example is presented and the results are discussed.