Cracking of Bucket Lugs in Pelton Turbines a Corrosion Fatigue Phenomenon

In recent years the tendency to increased size of generating units has also led to the putting into service of Pelton turbines of increased size and power. Most of the Norwegian plants have used designs with buckets attached to the turbine disc with bolts, either three lug
three bolt attachment of Norwegian design or two lug two bolt systems of foreign design. Recently, especially during the winter 1951-52 a number of fractures have occurred in buckets of very large units with two bolt type bucket attachment of foreign design. Following the adop-tion of more frequent and rigorous inspection a number of cracks have been discovered and the faulty buckets removes before serious damage occurred.