Which corrosion is associated with high flow and turbulence and accelerates material loss?

• A. Boric acid corrosion
• B. Pitting corrosion
• C. Flow accelerated corrosion
• D. Microbiologic corrosion

Answer: (C)

Flow Accelerated Corrosion is the process where high flow velocity and turbulence cause rapid, uniform thinning of metal by continuously removing the protective oxide film and enhancing the dissolution of iron into the surrounding water. In flowing systems, the protective layer on the metal surface can be stripped away by shear forces, and the thinner boundary layer under turbulent conditions allows oxidants and metal ions to move more readily to and from the surface. This combination accelerates material loss, especially in carbon steel piping in industrial and power plant environments, and it tends to occur in areas with high flow, such as near bends, tees, or constrictions where turbulence is greatest.

This mechanism is distinct from boric acid corrosion, which is a chemical attack related to boron species in reactor coolant chemistry, not specifically driven by flow dynamics. It’s also different from pitting corrosion, which produces localized, deep pits due to breakdown of the protective film at particular spots, rather than a uniform, flow-driven thinning. Microbiologic corrosion involves microorganisms creating corrosive byproducts or biofilms that alter the surface chemistry, again not defined by high-velocity turbulence.