99 Diseases of Pressure Equipment: Cavitation

Cavitation is the sudden formation and immediate collapse of vapor or air bubbles in a liquid stream when system pressure falls below the vapor pressure of the liquid. The sudden collapse of these tiny bubbles generates enormous, though tiny forces that mechanically damage (erode) metal (often on pump impellers or just downstream of let down valves). Typically the noise generated by cavitation is easily detectable and often sounds like stones rattling around in the pump or valve. Key to mitigation of cavitation is for operators to report such noise to engineers and inspectors so that steps can be taken to mitigate the cause of the cavitation. The other key to mitigation is for engineers and inspectors to let operators and maintenance personnel know about cavitation and how damaging it can be if it is not prevented. Material changes typically do little to solve the problem. Design or operating changes are usually necessary.

Might your operators know about strange noises coming from pumps and let down valves that have gone unreported?