Cause Analysis on Fracture of a Pump Shaft of Lye Transportation Pump in a Power Station

The pump shaft of a power station lye transportation pump fractured during operation, and the fracture reasons of the pump shaft were analyzed by means of fracture analysis, chemical composition analysis, metallographic examination, hardness test, tensile test, scale analysis and so on. The results show that the fracture of the pump shaft was partly because the shaft material was not quenched and tempered, which decreased its fatigue strength. On the other hand, the leakage of lye due to poor mechanical seal of the transportation pump resulted in the blockage of the clearance between the shaft sleeves by the resulting crystals, which made the pump shaft movement ineffective or even stuck. So the resistance of the pump and the torque of the shaft were increased, and fatigue brittle fracture occurred to the pump shaft.