Improvement of system availability using reliability and maintainability analysis

Abstract: System reliability, maintainability and availability have assumed great significance in recent years due to a competitive environment and overall operating and production costs. Performance of equipment depends on reliability and availability of the equipment used, operating environment, maintenance efficiency, operation process and technical expertise of operators, etc. When the reliability and availability of system are low, efforts are needed to improve them by reducing the failure rate or increasing the repair rate for each component or subsystem. The aim of this research study is to analyse operating reliability and availability for a system with periodically inspected and maintained components subjected to some maintenance strategy and find some importance measures that show the criticality of the components or subsystems. This analysis has helped to identify the critical and sensitive subsystems or components of the system that need more attention for improvement. In this research study we suggest a methodology for improving the availability of a repairable system. In the methodology, the concept of importance measures must be used to prioritize the components or subsystems for availability improvement processes. Availability importance measures show the criticality of each component based on different points of view such as availability, repair rate, and failure rate of each component. The reliability and availability of repairable systems can be improved by applying appropriate maintenance strategies; therefore a model is developed for selecting the most suitable maintenance strategies on based of analysis of reliability and maintainability characteristic of the operating system. The empirical data of two crushing plants at the Jajarm bauxite mine of Iran are used as a case study for reliability and availability analysis. The study shows that the reliability and maintainability analysis is very useful for deciding maintenance intervals, planning and organizing maintenance. The results show that availability and reliability importance measures can be used as a guideline for managing the efforts for reliability and availability improvement of a system.