This paper provides an overview of a steam turbine low pressure blades failures induced by flow excitation and blades torsional vibrations due to sudden changes on the grid. The analysis include L-0 and L-1 blades failures of the 110 MW [1], 28 MW [2] and 35 MW [3] geothermal units induced by unstable flow due to operation at low load low vacuum, and L-0 blades failure of the 660 MW [4] nuclear unit due combined effect of a transient phenomenon provoked by sudden load changes on the grid and some low vacuum operation period. The failure initiation was registered at different zones of the blades depending on the case, and were localized at the blades cover segments, blade root and blade airfoil close to the platform. Laboratory evaluation of the blades fracture surface indicates the failure mechanism to be high cycle fatigue (HCF).

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