A cost-informed component maintenance index and its applications

All systems and components are unreliable in the sense that they will fail. While a failed component in a system is being repaired (i.e., corrective maintenance), preventive maintenance (PM) may be conducted on the other components to improve the reliability of the system. The selection of different components for PM may result in a variety of maintenance policies with different cost implications. It is therefore necessary to develop appropriate tools such as importance measures to guide engineers in selecting components for PM in order to minimise relevant costs. There is little research, nevertheless, that jointly minimises the total expected cost of maintenance and maximises the number of components for PM. To fill in this gap, this paper proposes an importance index, Cost-Informed Component Maintenance Index (CICMI). It then derives some propositions of the proposed index and different maintenance policies, respectively. A method to optimise the number of components for PM subject to cost constraints is then proposed. A case study on a reactor coolant system is performed to illustrate the applicability of the proposed methods.