Continuous improvement of imperfect maintenance actions in PAS and PAR models

In this paper, an unavailability model is proposed to define the test and maintenance policies of systems that are subject to hidden failure and degradation, assuming practices of continuous improvement (CI) under imperfect maintenance actions with Proportional Age Setback (PAS) and Proportional Age Reduction (PAR). For this, two CI equations are analyzed to estimate the progress of maintenance effectiveness over time, and a maximum unavailability constraint is incorporated into the model for evaluation of safety point of view. A numerical application was performed, and the results showed that by adopting CI practices over maintenance actions, the unavailability of the system is reduced in greater proportion over time, besides contributing positively to safety.

Application of Reliability-Centered Maintenance for Tugboat Kresna 315 Cooling Systems

Reliability-Centered Maintenance uses the risk management principle of a component’s failure so that the type of maintenance can be determined properly. By using an appropriate type of maintenance, the possibility of failures in a component can be detected and prevented. The proper usage of Reliability-Centered Maintenance can have a positive impact on cost savings, both maintenance costs and repair costs, as well as reducing the consequences of failures. The object of this research is the cooling system aboard Tugboat Kresna 315. The cooling system is an important system on a ship, which is designed to prevent the main engine from overheating. The aim of this research is to apply Reliability-Centered Maintenance methods on the cooling system of Tugboat Kresna 315 and determine the types of maintenance tasks required. The results of Reliability-Centered Maintenance identified 16% of the overall failures to be a type of hidden failure while 86% were identified as evident failures, thus allowing the maintenance division to perform maintenance activities in accordance with the planned maintenance system on each tugboat.