Toward Pipe Wall Thinning Model Development Based on Mass Transfer Coefficient (Simultaneous Measurement of Mass Transfer and Velocity Field)

Flow Accelerated Corrosion (FAC) is one of the issues to be noticed considerably in plant piping management. For the integrity and safety of the plant, the wall-thinning and thinning rate due to FAC should be predicted, and we hope to construct the model to predict the wall thinning rate. We have studied FAC from the view point of flow dynamics. The mass transfer coefficient and the velocity fluctuation are measured simultaneously behind the orifice in pipe. The former is obtained by the electrochemical method and the latter is PIV measurement. Space-time correlation and conditional sampling technique reveal that the large scale motions play an important role for the mass transfer rate at the wall and there is a time lag between mass transfer and velocity fluctuations. They may be useful for the model to evaluate the wall-thinning rate.