Bi-Criteria Optimization for Finding the Optimal Replacement Interval for Maintaining the Performance of the Process Industries

Bi-Criteria Optimization for Finding the Optimal Replacement Interval for Maintaining the Performance of the Process Industries

Harish Garg (Thapar University, India)
DOI: 10.4018/978-1-4666-9644-0.ch025
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The optimization of the maintenance decision making can be defined as an attempt to resolve the conflicts of decision situation in such a way that variable under the control of the decision maker take their best possible value. One of the most important controllable parameters is the time interval between maintenance. Most of the researchers have kept the fact that whenever the suitable maintenance interval is reached, the system is replaced with the original one. However the improvement of a system life not only depends on the replacement of deteriorated components, but also on the effectiveness of the maintenance. Taking care about this fact, the effects of maintenance of a multi-component system by combining the three main different PM actions, namely (1a), (1b) and (2p)-maintenance actions. Thus, the main purpose of an effective maintenance program is to present a technique for finding the optimal maintenance interval for the system by considering the multiple goals of the organization viz. maximum availability, minimum maintenance cost.
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1. Introduction

With the advance in technology, a designer always wants to manufacture the equipment and systems of greater capital cost, complexity and capacity which results in increasing the reliability of the system. Also at the same time the unfortunate penalty of low availability and high maintenance cost need to be improved for their survival. To achieve this end, availability and reliability of equipment in the process must be maintained at the higher order. Thus, reliability and maintainability concepts are mainly applicable at the design stage of a machinery or plant layout, while the availability concept is mostly applicable after commissioning the plant or after a steady state of production is reached. Modern technology has developed a tendency to design and manufacture equipment and systems of greater capital cost, sophistication, complexity, and capacity. The disastrous consequences of low availability and high maintenance cost of such systems led to the desire for high reliability, high maintainability, and low mean time to support. Due to design problems and poor product support, manufacturer equipment and systems are not able to meet these requirements. However, to improve the quality and quantity of a manufactured associated prospectus, there is a need to accentuate more on operational management and the proper consideration of reliability, availability and maintainability (RAM) in the design, manufacturing and installation phase will could be reduced the number of failures and their consequences minimized (Saraswat and Yadava, 2008). Thus, for this reason and to reduce the number of likelihood failures, there is a great interest in dealing with the main feature of the reliability parameters which affects the system performance directly i.e. reliability, availability and maintainability. In that direction, various researchers have addressed the issue of RAM analysis by adapting the suitable maintenance strategies for increasing the performance of the system (Saraswat & Yadava, 2008; DuJulio & Leet, 1988; Wood, 1989; Madu & Kuci, 1994; Hwang, 1996; Zerwick, 1996). To improve the system reliability and availability, implementation of appropriate maintenance strategies play an important role. The high performance of these units can be achieved with highly reliable subunits and perfect maintenance. To this effect the knowledge of behavior of system, their component(s) is customary in order to plan and adapt suitable maintenance strategies. Thus, maintainability is also to be a key index to enhance the performance of these systems.

Key Terms in this Chapter

Exploitation: Exploitation is the process using information gathered from previously visited points in the search space to determine which places might be profitable to visit next.

Preventive Maintenance (PM): It is planned maintenance of plant and equipment that is designed to improve equipment life and avoid any unplanned maintenance activity. It includes painting, lubrication, cleaning, adjusting and minor component replacement to extend the life of equipment and facilities. Its purpose is to minimize breakdowns and excessive depreciation. Neither equipment nor facilities should be allowed to go to the breaking point. In its simplest form, preventive maintenance can be compared to the service schedule for an automobile.

Exploration: The process of visiting entirely new regions of a search space, to see if anything promising may be found there.

Reliability: It is a characteristic of an item (component or system), expressed by the probability that the item (component/system) will perform its required function under given conditions for a stated time interval.

Evolutionary Algorithm (EA): A collective term for all variants of (probabilistic) optimization and approximation algorithms that are inspired by Darwinian evolution. Optimal states are approximated by successive improvements based on the variation-selection paradigm. Thereby, the variation operators produce genetic diversity and the selection directs the evolutionary search.

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