Study on Pipe Wastage Mechanism by Liquid Droplet Impingement Erosion II (Measurement of Erosion Rate)

Abstract

Evaluation of wastage rate for nuclear power plant piping is important in maintaining plant reliability and safety. The two commonly well known causes of pipe wastage are liquid droplet impingement erosion (LDIE) and flow accelerated corrosion (FAC). This study is to evaluate the wastage rate of pipe wall and to measure the loss of mass caused by LDIE. A high speed rotating disk and water jet is used to perform LDIE phenomena. In this study, the liquid droplet impinging tests were conducted with the test piece mounted on the high speed rotating disk which crosses thin water jet. The amount of the wastage by LDIE was evaluated by changing the rotational speed, test time and test piece materials. After the experiment, the result of erosion was investigated by observing the surface of the test piece using a digital microscope, and photo was taken. A method of converting the photo into data is used. In this study, LDIE is considered as the main cause of test piece mass difference before and after the experiment. Therefore, a method is designed to evaluate the mass difference. In this method, the difference in volume of the material is calculated. The loss of mass is obtained by multiplying the difference in volume and density of the material. Then, 2-dimensional and 3-dimensional graphs of the test piece are drawn. The analytical code TRAC is used to analysis the liquid droplet velocity in Advance Boiling Water Reactor (ABWR) drain pipe.