What might cause very small pin-hole leakage near the output fitting of a metallic-body centrifugal cooling water pump?

The presence of very small pin-hole leakage near the output fitting of a metallic-body centrifugal cooling water pump can indeed be attributed to erosion caused by high-speed water flow. In a centrifugal pump, as the water is accelerated through the impeller and discharged at high velocity, it can create wear on the internal surfaces of the pump. This continuous erosion can lead to the gradual degradation of the material, ultimately resulting in tiny pin-hole leaks.

When water flows at a high velocity, it exerts significant force against the surfaces it comes into contact with. Over time, this force can wear away the material at points where the flow is turbulent or concentrated, especially around fittings where the direction of flow changes. These wear points can develop into small holes that allow water to escape.

In the scenario of a centrifugal pump, ensuring proper material selection and monitoring the wear over time is essential to prevent such leakages. Maintenance practices may also involve inspecting for signs of erosion and replacing components as necessary to maintain efficient operation and prevent unwanted leaks.