An integration of multi-criteria decision making techniques with a delay time model for determination of inspection intervals for marine machinery systems

• A novel tool integrating MAUT, ELECTRE and AHP with delay time model.
• AHP used to determine decision criteria weights.
• MAUT and ELECTRE used to rank alternative inspection intervals.
• Close correlation between results obtained from MAUT and ELECTRE methods.
• MAUT method is more robust and less sensitive to decision criteria weights and Weibull parameters variation.

For certain critical equipment items in marine machinery systems, the optimum maintenance strategy would be a scheduled on-condition operation. This involves inspection of the equipment items in order to monitor their performance degradation and, invariably, carry out repair or replacement tasks. The main challenge with this type of maintenance approach is the determination of the appropriate interval for performing the inspection task. This paper presents a methodology which integrates multi-criteria decision making (MCDM) tools with a delay time model for the determination of optimum inspection intervals for marine machinery systems. With this approach, multiple decision criteria are modelled with the delay time concept and aggregated with MCDM tools such that different criteria can be applied simultaneously in the ranking of different inspection interval alternatives. The applicability of the proposed methodology is demonstrated using the case study of a water cooling pump of the central cooling system of a marine diesel engine.