Indian Journal of Science and Technology

Abstract

Objectives: To analyze the effect of conducting maintenance inspection on equipment at subsystem level and at group level on the downtime per unit time for the equipment. Methods/Analysis: Using Delay Time Analysis (DTA). Taguchi design of experiments is sought to synthesize the data sets to involve the realistic effect of four DTA parameters, defect arrival rate, inspection time, breakdown maintenance time and the delay time distribution parameter, whose levels have been adjusted to match normal situations prevail in industry with some rounding off. Numerical example is shown for the consequence variable of downtime per unit time, computed at subsystem level and at equipment level. Findings: Subsystems fit for maintenance inspection can be segregated from those which should be left out for breakdown maintenance strategy by simple method, which is discussed. To aid the group inspection strategy, mathematical models to arrive at the data aggregates are presented, the extension of which can lead to plant level data aggregation too; the way the inspection time can be applied in a parallel or series manner on all subsystems have been discussed. The indicator, the downtime per unit time which is computed based on aggregates can mislead the planner is pointed out for making out a better decision while deciding maintenance inspection intervals. The grouping analysis has finally led to three strategies for the practitioner to choose from while implementing DTA based maintenance inspection, the circumstances in which one can resort to any strategy is also indicated Conclusion/Application: Three strategies, Single inspection, Grouped inspection-series and Grouped inspection-parallel are available for the practitioner when planning PMI through DTA,. Certain parts can be left to breakdown maintenance strategy. Caution is given about possible creeping up of error due to data aggregation in grouped inspection.

Keywords: Delay Time Analysis, Grouped Inspection, Maintenance Inspection Interval