FAC rate measurement downstream from an Orifice

In this study, the corrosion rate on the pipe wall downstream from an orifice was measured in order to validate the evaluation code for flow-accelerated corrosion (FAC). Three orifices with aperture ratios β = 0.62, 0.50, 0.41 was used in a test section with 50mm inner pipe diameter. The flow velocity was changed during the test to investigate the effect of mean cross-sectional flow velocity on the FAC rate. The water conditions were 150 degree centigrade, about 0.1ppb of dissolved oxygen concentration and neutral of pH without any chemical additives. The FAC rates were calculated using electrical resistances of sensor plates made from carbon steel STPT42. The measured data were provided to the research committee 'Research Committee on application of new findings and technology to improve pipe-wall-thinning management' in Japan Society of Mechanical Engineers, and were applied to evaluation-code validation and the discussion of the future management using prediction and inspection. (author)