Studies on Flow and Pipe Wall Thinning and the Reduction in the Downstream of Orifice Nozzle

In a piping system of power plant, pipe wall thinning by Flow Accelerated Corrosion, FAC, Liquid Droplet Impingement Erosion, LDI, and Cavitation Erosion, C/E, are very serious problems because they give a damage and lead to the destructtion of the piping system^[1]–[6]. In this study, the pipe wall thinning by FAC in the downstream of orifice nozzle, flow meter, is examined. Namely, the characteristics of FAC, generation mechanism, and prediction of the thinning and the reduction are made clear by experimental analysis. As a results, it was made clear that (1) the thinning is occurred mainly according to the size of the pressure fluctuation p^′ on the pipe wall and the thinning can be estimated by it, and (2) the suppression of p^′ can be realized by replacing the orifice to a taper shaped one having an angle to the upstream.