Use of stochastic petrinets in modeling of safety device inspection interval problem

Abstract

The paper discusses the issue related to simplification of maintenance process modeling which has got a direct relation with the appropriateness of the maintenance decisions and the resulting reliability of the concerned equipment or system. For years the maintenance engineers on ground have lamented the complexity of the mechanical system and the difficulties in trying to model its failure processes using mathematical models. As a result, in spite of many serious attempts by the researchers, the maintenance engineers on ground still follow the ‘thumb rule’ or equipment manufacturer’s recommendations for maintenance. Stochastic petrinets established as a useful tool for graphical modeling for analysis of communication protocols can be fruitfully used to simplify this modeling process and allow even the field level engineers to analyse their systems and make the right maintenance decisions. Encouraged by the results of use of stochastic petrinets for modeling the wear/failure problem of stern tube bearing of ships, the author in this paper demonstrates the use of stochastic petrinet tool for modeling and analysis of a safety device inspection problem. The safety device is installed to prevent catastrophic failure of an equipment. Failure of the safety device is hidden and only reveals itself during an inspection. Steady state probabilities evaluated using simulation based on stochastic petrinet tool are compared with the results evaluated analytically.