Damage analysis and restoring of structural integrity of Pelton runner after repair welding: case study

Abstract

This paper presents the repair welding technology of a Pelton runner blade, including an analysis of damage caused by cavitation. Extreme exploitation conditions resulted in crack initiation followed by its propagation to a length 200 mm, detected during regular annual maintenance, compromising Peltron turbine’s structural integrity. The base material of the Pelton turbine is steel X3CrNiMo13-4, and as well as the blade geometry itself, required special attention during the process of defining the repair welding technology. An austenitic electrode was used for this purpose along with a welding technology defined in a way to counter the initiation of new cracks at the same location. Following the NDT, the Pelton runner was put back into exploitation, along with recommendations for further monitoring