Valve cavitation

If the valve is in a state with a large throttling range, cavitation is likely to occur on the back side of the valve disc; it is generally used at angles greater than 15°.

The valve body is usually a cast part, and if cavitation is severe, the valve must be replaced.

Let’s see if it’s possible to weld it back together; if the damage is too severe, then the valve will have to be replaced. The valve body has become honeycombed due to cavitation. What about the internal components of the valve? Is there no picture? Could you send it over for me to take a look?

It’s all corroded and formed a honeycomb pattern; even after repair, the quality can’t be guaranteed. It’s best to replace it.

It’s better to replace it with a new valve, if it’s not a very expensive one.

When this happens, it is usually necessary to replace the valve. The traffic will be unstable after repair

I agree to replace the valve, but it would be advisable to re-examine the selection of the control valve to avoid the same problem occurring in the future.

First, you need to understand why cavitation occurs. Cavitation happens when a medium under normal pressure and flow velocity passes through the valve seat of a control valve; that area acts as a bottleneck, causing the medium to be compressed and thus flow at high speed. When the medium reaches the valve stem, its volume increases, which reduces its pressure below the saturated vapor pressure, leading to vaporization and the formation of bubbles. Later on, the pressure in the valve returns to normal levels, exceeding the saturated vapor pressure, and the bubbles burst. These bursts are like tiny bombs that explode behind the valve stem, at the valve seat, and in the rear part of the valve body. Since the bubbles keep bursting, this impact is continuous. Although each bubble’s explosive force is small, the cumulative effect on the valve body and stem can be quite significant, especially under high pressure differences, where cavitation is particularly severe. The rupture of bubbles cannot be prevented; it is only possible to shift the location where they rupture. Current solutions involve using labyrinth-style valve internals, so that the point of bubble rupture occurs inside these internals rather than on the surface of the valve body or valve stem, thereby avoiding damage to them. The damage caused by cavitation can be repaired by fixing the valve core, but it won’t last long; choosing cavitation-resistant components is the true long-term solution