Unscheduled replacement of HP control stage blades due to solid particle erosion can be avoided if the structural integrity of the eroded blade has not been compromised, and the risk of an in-service failure is shown to be minimal. An analytical approach is presented which was used to evaluate whether blades with SPE damage could remain in service until the next convenient outage, in order to provide the plant engineers with specifications to assist them in determining the need for replacement based on further observed erosion damage. A three-dimensional fracture mechanics model was applied to study the propagation of cracks caused by erosion, and to assess when rupture was likely to occur. The results of the study are presented as a model for plant operators to use in scheduling the repair or replacement of HP blades.

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