Failure analysis of an impeller blade

Abstract

A multi-stage low-pressure centrifugal air compressor used in the utility section of a manufacturing plant tripped. An increase in vibration was recorded prior to the breakdown. Subsequent inspection revealed that a small part of one blade had fractured and separated from the impeller body. The failure occurred in the 3rd stage impeller blade employed in a three-stage compressor with two interstage cooling tanks. The air compressor had been in service for 18 years while the current impeller had been used for 18 months. Impeller was made of 17-4 PH steel. Scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, and Vickers hardness testing were used to metallurgically evaluate the broken blade and corrosion deposit obtained from cooling tank. Experimental results indicated that the mode of failure of the impeller blade was corrosion fatigue. Hardness of impeller material was also found to exceed the upper limit required to use it in sulfur bearing environment. Cause of failure can be attributed to intense vibrations in the compressor system responsible for the generation of stresses that led to the fatigue failure of impeller blade already embrittled due to improper heat treatment and exposed to an environment made corrosive due to the presence of sulfur.

Power Quality Improvement of a Hybrid Renewable Energy Sources Based Standalone System Using Neuro-Fuzzy Controllers

“…When the impeller is damaged, the centrifugal pump will also reduce its life. If it is not discovered and repaired in time, a major accident is likely to occur [9,10]. Then the impeller, an important part of the centrifugal pump, has high practical significance for its fault diagnosis research.…”

Perspective Chapter: Fatigue of Materials

“…Machinery equipment's such as compressors, turbines and pumps are more prone to this type of damage. Numerous destructions in these devices have been reported due to incorrect design or manufacturing defects and have caused loss of production and financial resources [16][17][18][19]. Failure of a Ti6Al4V alloy compressor impeller used in a petrochemical plant is shown in Figure 1.…”