Managing the maintenance of industrial plants is an important factor of competitiveness. Works presented within this publication show the modeling of an industrial system example coming from the literature: the AGR system; to evaluate maintenance strategies. Two tools are used with different level abstraction on the system. The mp-sim tool considers the component level. The OpenAltaRica platform considers the system level. These tools are based on the stochastic discrete event systems mathematical framework. Indicators to assess on these models are calculated by stochastic simulation.