Abstract
A risk-based maintenance system was established to improve economical benefits of maintenance based on probabilistic risk assessment. The system has four subsystems for field data management, for probabilistic life assessment, for probabilistic risk assessment and for maintenance planing. Unreliability functions of operation hours or number of starts were derived from the reliability analysis of field inspection data and the life assessment using statistical material data. The risk was calculated by summing up the recovery costs expected by the unreliability along event trees. The maintenance planning was conducted by comparing operation benefits, preventive maintenance costs and risk costs. This system can be applied to various types of steam turbines by using the unified unreliability functions expressed by life or event governing parameters.
