Age replacement and inspection models for estimating optimal maintenance cost: numerical performance comparisons with a case study from chemical industries

Regular preventive maintenance activities such as inspections and replacements are crucial for ensuring the optimal performance of operating units, even though they may lead to higher maintenance costs. In this context, this paper presents a comparative study of two maintenance strategies, namely the age replacement model and the inspection model, using the maintenance expected cost as the primary criterion. The study evaluates both models for Weibull and Gamma distributions with increasing hazard failure rates. A numerical sensitivity analysis is performed to compare the models and determine the optimal strategy by combining cost per distribution. The study also examines the impact of varying parameters the shape parameter, preventive maintenance cost, failure cost, and inspection cost on the expected cost. The proposed models are applied to model the maintenance of a centrifugal pump, first as a single-component system and then as a 5-independent component system. Results indicate that the inspection model is more advantageous and provides better outcomes in terms of minimizing servicing costs for individual maintenance strategies. The study highlights the importance of carefully selecting appropriate replacement and inspection models to ensure efficient and cost-effective maintenance management of the system, which can significantly reduce servicing costs. The findings of this study can assist maintainers in selecting the best maintenance strategy for their systems.