Mathematical modeling of orifice downstream flow under flow-accelerated corrosion

The main objective of this paper is to establish an analytical model to evaluate the rate of corrosion in a horizontal pipe downstream of an orifice under flow-accelerated corrosion (FAC). FAC is a major issue causing the wall thinning of carbon steel piping in power plants. In this work, the dimensional analysis was employed using the method of repeating variables and the Buckingham Pi Theorem. It was found that the Sherwood number and the relative distance from orifice are the main dimensionless parameters influencing FAC downstream of an orifice. Concerning the available experimental data, two different cases considered; orifice ratio (OR) of 0.25 and 0.5. The result of mathematical modeling agreed with the experimental data. The maximum value of the FAC rate could be well-predicted for the OR of 0.25, while the location of the maximum FAC rate could be well predicted for the OR of 0.5. It was found that the maximum value of FAC rate increases with decreasing orifice ratio and also the maximum value will be located between 1 and 4dp downstream of the orifice in both cases. This work could be useful for professionals in industry and researchers in the field and could be the starting point for a new way of evaluating the FAC rate downstream of a flow's singularity.