Case study: Evaluation of L-1 Steeple Repair Strategy
Stage: L-1 stage in a base load LP steam turbine
Issue: Crack indications have been found in the L‐1 steeples with axial curved entry blade roots
Objectives: FEA analyses to evaluate the stresses resulting from modifications by grinding out cracks in the steeple grooves
Crack indications have been found in the L‐1 steeples with axial curved entry blade roots.
Modifications by grinding out cracks with different profiles were proposed.
FEA was performed to evaluate the impact on stresses and associated risk as a result of modification to repair the damage steeple.
Summary of Analyses
FEA analysis shows that steady stresses in the original and modified L-1 steeples are NOT excessive to pose a significant threat to the structure integrity under a base load operation.
Cracking might be associated with corrosion assisted fatigue.
The proposed modifications were studied and optimal configuration was recommended.