Assessment of flow-accelerated corrosion-induced wall thinning in SA106 pipes with elbow sections

A combination of flow-accelerated corrosion (FAC) tests and corresponding computational fluid dynamics (CFD) tests were performed to determine the hydrodynamic parameters that could help predict the highly susceptible location to FAC in the elbow section. The accelerated FAC tests were performed on a specimen containing elbow sections fabricated using commercial 2-inch carbon steel pipe. The tests were conducted at flow rates of 9 m/s under the following conditions: water temperature of 150 °C, dissolved oxygen <5 ppb, and pH 7. Thickness reduction of the specimen pipe due to FAC was measured using ultrasonic testing. CFD was conducted on the FAC test specimen, and the turbulence intensity, and shear stress were analyzed. Notably, the location of the maximum hydrodynamic parameters, that is, the wall shear stress and turbulent intensity, is also the same location with maximum FAC rate. Therefore, the shear stress and turbulence intensity can be used as hydrodynamic parameters that help predict the FAC-induced wall-thinning rate. The results provide a method to identify locations susceptible to FAC and can be useful for determining inspection priority in piping systems.