Cavitation Erosion Features in Industrial Control Valves at an Inlet Pressure of 20 MPa

概要

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Cavitation erosion of control valves is one of serious problems frequently arisen in industrial plants dealing with high pressure liquid flows. Nevertheless, there have been only slight empirical data helpful in estimating the valve life and diagnosing the valve performance deterioration in relation to the erosion development. A needle-type contoured plug inserted in a low C_v-value globe valve has been subjected to erosion tests using a 20 MPa high pressure water facility. Several factors affecting the erosion development are obtained by the present experiment. On materials of plug metal, the rate of mass loss by the erosion decreases in the order of brass, Stainless Steel-316, Stainless Steel-630, Stainless Steel-440C and Stellite#6. The loss rate is found to take an extremely high level as the valve is opened at its full lift. The erosion feature is largely altered by a slight change in the plug geometry, oxygen amount of the water and also level of the outlet pressure. These effects are compared in terms of the eroded mass rate data. Cavitation pictures obtained by a low pressure facility at a level of 1MPa are also presented as supplementary data to specify the erosion part on the plug depending on the cavitation bubble behaviors.
1998-11-15