Critical flow velocity phenomenon in erosion-corrosion of pipelines: determination methods, mechanisms and applications

Abstract The critical flow velocity phenomenon is common in erosion-corrosion of many materials. It is of great importance to develop methods to determine the critical flow velocity and understand mechanisms of the phenomenon so that it can be used for proper applications. This paper provides a critical review of the critical flow velocity phenomenon in erosion-corrosion of pipelines in terms of its determination methods, mechanisms and applications. Three types of determination methods, including mass loss, electrochemical measurements and surface roughness, are reviewed and discussed. In particular, the potentiostatic polarization method is recommended to determine the critical flow velocity. The mechanisms of the critical flow velocity phenomenon depend on the surface film, which include passive film, corrosion products film and inhibitor adsorption film, formed on the metal surface. Parametric effects on the critical flow velocity are analyzed. Finally, the applications of the critical flow velocity phenomenon are considered for material selection and surface modification for improved resistance to erosion-corrosion.