An integrated framework for mode failure analysis, delay time model and multi-criteria decision-making for determination of inspection intervals in complex systems

This paper aims to propose a framework for the definition of an inspection policy with three main elements: evaluation of failure modes (MF) of a system, selection of the criteria that best represent each dimension of failure modes and a process for determining inspection actions through a multi-criteria approach. The proposed modeling consists of determining the inspection interval for each mode of failure, considering that the MF has different consequences under different criteria. To meet this goal, first, the system and its respective failure modes are identified. Then, the consequences of the MF are classified according to a logical decision diagram that assists the decision-maker in identifying the criteria to be used in modeling, which may vary between cost, downtime, safety, environmental, quality and reputation, selecting among them the one (s) that best represent each mode of failure. Finally, the inspection intervals are determined for each MF using a multiple-criterion decision analysis (MCDA). By applying the framework proposed in a subsystem of a thermoelectric plant, it was possible to determine the inspection interval for each failure mode. Through the proposed model, it was possible to introduce a broad view of the decision problem and to focus attention on the failure modes that have the greatest impact.