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Failures often observed in two types of components in two very different plants, due to a similar cracking
phenomenon, are here discussed: blades of steam turbines of geothermal power units, and elements of
elecrostatic filters at the inlet of exhausted chemins in fossil fuelled power plants. In both components
failures are due to high cycle fatigue with high R-ratio, with cracks starting from corrosion pits. A fatigue
fracture model is presented, based on service stress exceeding the material fatigue endurance limit at the
notch tip region of the largest pits. From periodically ispecting pit depths, recommendations may be
derived for maintenance decisions, depending on the "distance" from the critical pit sizes.