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

Abstract

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.

Determining the Optimal Maintenance Strategy for Ammonium Hydroxide ‎Production Unit Using Risk-Based Inspection ‎and Analytic Hierarchy Process

“…In the second stage, the pairwise comparisons of the alternatives and criteria are carried out. Let C=(Cj |j=1,2,...,n) be the set of criteria, an (n×n) evaluation matrix A, with elements of aij (i,j=1,2,...,n) showing the quotient of weights of the criteria, summarizes the pairwise comparison on n criteria, as depicted in Equation (5). In this study, the pairwise comparison mechanism for each criterion and alternative is done based on Table 6 which was proposed by Saaty.…”

“…Nowadays, there is an increasing attention to the risk-based methods for developing inspection, maintenance, and repair strategies in oil, gas, petrochemical, and power plant industries. The main reasons are the complexity of production processes in these industries, expensive equipment used, extra costs due to unexpected stops and overhauls, environmental contamination, and the importance of optimal usage of these processes [4,5].…”

Functional Model of Integrated Maintenance in Petrochemical Industries

“…budget and profitability of industries, and the lack of proper planning of maintenance in the organization reduces the useful life of the equipment (2). Great attention to science of maintenance is necessary to respond to the expectations of industries, which is due to the limited resources such as energy, manpower, and capital, with suitable planning and its principled implementation, can lead to an increase in productivity, efficiency.…”