Major Failure Modes of Centrifugal Pumps
Since centrifugal pumps are one of the world’s most widely used type of pump, their operational parameters and also their vulnerabilities are well known. This article reviews the major failure modes that are found in centrifugal pumps. In general, pump failures result in operational changes that reduce efficiency or may result in a breakdown of the pump. Reliability of hydraulic systems and also centrifugal pumps is of the highest importance in nuclear engineering.
The failure modes of centrifugal pumps can be grouped into three categories:
Hydraulic Failure Modes
- Cavitation. Cavitation is, in many cases, an undesirable occurrence. In centrifugal pumps, cavitation causes, damage to components (erosion of the material), vibrations, noise and a loss of efficiency.
- Pressure Pulsation. Pressure pulsations are fluctuations in the basic pressure. For high-head pumps, suction and discharge pressure pulsations may cause instability of pump controls, vibration of suction and discharge piping, and high levels of pump noise.
- Pump Recirculation. A pump operating at lower capacity than design limits can suffer from recirculation which occurs internally in the pumps. Pump recirculation can cause surging and cavitation even when the available NPSHa exceeds the supplier’s NPSHr by considerable margin.
- Radial and Axial Thrust. High radial thrust that results in excessive shaft deflections may lead to persistent packing or mechanical seal problems, and possibly, shaft failure. Axial thrust is imposed along the shaft axis. High axial thrust may impose an excessive load on the bearing.
Mechanical Failure Modes
- Shaft Seizure or Break
- Bearing Failure
- Seal Failure
Other Failure Modes