Searching for Gas Turbine Maintenance Schedules

costs associated with them but is also costly when done frequently. That is why substantial efforts have been invested in minimizing the expected total cost due to failures and preventive maintenance of industrial equipment (Dekker 1996, Tan and Kramer 1997, Bäckert and Rippin 1985, Dekker and Scarf 1998). In industry, most preventive-maintenance approaches include the use of fixed schedules, optimized in advance for minimum cost. However, there are many situations in which maintenance replanning is necessary to operate with as low cost as possible. For example, unexpected breakdowns force the production unit to stop for emergency repair, and performing other maintenance tasks at the same time can save time and money. In addition, the increasing use of condition monitoring leads to more unpredictable maintenance events and a need for dynamic planning. In this article, we present the ideas behind the preventivemaintenance optimizer (PMOPT) tool used to optimize gas turbine maintenance schedules. We developed PMOPT for Siemens Industrial Turbomachinery AB (SIT AB), one of the leading manufacturers of gas turbines of small and medium size. Gas turbines are used for power generation in various production facilities that often have high down time costs. A gas turbine in the form of a jet engine is depicted in figure 1. Axial flow gas turbines (including many industrial gas turbines) are constructed using a compressor, which produces compressed air to a combustion chamber, where fuel is injected. The resulting mixture is Articles