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 in the liquid, resulting in tiny, yet powerful, shockwaves that can, over time, cause significant damage to metal. In the process industries, cavitation generally occurs in a liquid stream when the system pressure falls below the vapor pressure in the liquid. These often includes pump impellers, areas just downstream of let down valves, and pipe bends where a sudden change in liquid direction occurs.
The damage from cavitation most often manifests as wear or pitting on the surface of the metal. This wear is caused by the cyclic stresses of the repeated shockwaves caused by the collapses of the cavities. While an individual collapse is relatively harmless, numerous collapses can cause erosion over time.
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July/August 2003 Inspectioneering Journal
By John Reynolds at Intertek
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). |
