Availability based comparison of fixed age and life cycle cost replacement maintenance

Determination of the best approach to preventive replacement maintenance on repairable systems can guarantee maximum efficiency. Availability comprises both reliability and maintainability, and can be considered more suitable in system replacement analysis. The paper investigates the economic replacement period for a typical repairable system in a manufacturing industry, called Rex Company in this paper for privacy. The system had a design replacement period based on fixed age, which was compared with the replacement period from the research. The mean availability of the system over the studied period was approximately 50%. The result show that the 19 years replacement period obtained from analysis of maintenance cost data is in very fair agreement with the designers' estimate of 20 years, though the Authors were not privy to the method of remaining useful life estimation used by the designers. However, the authors argue that the research result is superior to the fixed age replacement period given by the manufacturers. This conclusion is predicated on the non-linearity of the availability of the centrifugal pumps during the study stretch. The result also shows that availability evaluation can offer a good insight to determining the replacement period of deteriorating systems.