炭素鋼配管エルボ部における表面性状とFAC減肉速度に関する一考察

抄録

Scallop pattern is widely recognized as a typical morphology on the corroded surface by high flow-accelerated corrosion (FAC) rate in single-phase flow. Although turbulence flow condition could be closely related to scalloped appearance, the detailed process of scallop development is not fully known. In this study, systematic and quantitative characterization of scalloped appearance (scallop size, depth, and density) on the corroded surface of the carbon steel piping elbow used in fossil power plant have been carried out. The FAC rate lineally decreased from the center of dorsal (0-degree) to ventral side (180-degree), while the scallop patterns disappeared completely at the 70-degree part which showed approximately half of the maximum FAC rate. It has been notable that there was no significant increase of the FAC rate by scallop formation although the local turbulence was increased by hydrodynamic effect due to scallop surface.