A motor on a boiler feed pump in a petrochemical plant failed, shutting down the plant production. The failed feed pump motor is shown in Photograph A.
Photograph A: Overall view of failed motor.
A metallurgical failure analysis was requested. Non-Destructive Metallurgical Failure Analysis included visual, macro and microphotography, stereomicroscopic examination, and output motor shaft runout. Cutting and destructive testing of the motor shaft and debris was performed to facilitate handling, metallographic examination, scanning electron microscopy, energy dispersive spectroscopy (EDS), and hardness/microhardness testing.
The information gathered from this testing strongly suggested that the failure of the subject motor was the result of the manufacturing, balancing, and casting defects, i.e., gas and shrinkage/micro shrinkage porosity, laminations, weak grain boundaries, and improper rotor balancing.