Fatigue Failure Analysis of Pump Shaft of a Hydraulic Coke Removal System

Failure of pump shaft (P116-1) of high-pressure water pump occurred during coke removal. Shaft material (3Cr13) demonstrated yield and tensile strength of 737 and 910 MPa, respectively. Failure analysis was performed to determine the cause of failure, which was a fracture at the pump shaft located at the journal. Macroscopic, metallographic, chemical composition, hardness, SEM, and EDS analyses were used in the failure analysis. Metallographic and SEM analyses revealed that fatigue cracks are related to corrosion and geometrical shape. Fatigue crack initiation at the disconnected area of the chromium plating layer weakened fatigue resistance. Causes of incomplete chromium plating at the shaft journal and keyway should be investigated further.