If you have ever worked with centrifugal pumps, chances are you have personal experience with the issue of broken shafts. However, you may not have a good understanding of the reasons why centrifugal pump shafts break. Here is some information about the top three causes of broken centrifugal pump shafts.
Metallurgical/Manufacturing Process Flaws
Manufacturing and metallurgical process flaws are one cause for centrifugal pump shafts to break. Flaws can shorten the lifetime of shafts and cause them to fail prematurely. When a shaft breaks prematurely, many people blame the manufacturer. However, the truth is that shaft breakage is often a result of the operating conditions of the pump. Manufacturing flaws are rarely the cause of shaft failures.
Vibration is typically caused by misalignment between the motor and pump shafts for long coupled centrifugal pumps. Other system problems such as cavitation, and operating outside the best efficiency point for the pump can cause excessive vibration as well. The pump bearings start to wear, and the shaft begins to move laterally. This causes the shaft to flex and then fail. The vibration harmonics place extra stress on the shaft of the pump.
Imbalance causes problems while the centrifugal pump is running. Some of the factors that tend to cause impeller imbalance include the following:
- Trimmed and an unbalanced impeller
- A new and unbalanced impeller
- Vanes are out of plane or bent
- A foreign object stuck in the vanes
- There is a buildup of product on the impeller
- A plugged balance hole
For more information about the top three causes for centrifugal pump shafts to break contact the professionals at W. P. Law, Inc.