Failure Analysis of a Twin-screw Pump Shaft

Through physical and chemical properties testing, and analyses of SEM, EDS and XRD, the fractured shaft of a twin-screw pump was analyzed. The results showed that the reason of the fracture was corrosion fatigue cracking caused by sulfide corrosion. The shaft was the first part to fracture, the screw shell was the second element to fracture; transport medium containing hydrogen sulfide gas and long-term torsion movement were the mail reasons leading to the shaft fracture.