How does high flow rate affect corrosion in pipelines?

• A. High flow can erode protective films and increase corrosion
• B. High flow reduces corrosion by washing away contaminants
• C. Flow rate has no effect on corrosion
• D. High flow causes only uniform corrosion

Answer: (A)

High flow rate increases corrosion because the moving fluid can physically wear away protective films and coatings on the metal, exposing fresh, more reactive metal to the environment. This erosion of the protective oxide or scale means the surface isn’t passivated and can corrode faster. At higher velocities, the boundary layer that normally slows diffusion becomes thinner, so more oxidizing species (like oxygen or dissolved CO2 forming carbonic acid) reach the metal surface and accelerate the anodic reactions. Turbulence from rapid flow also promotes localized attack, leading to erosion–corrosion rather than just a uniform rate.

So, the statement that high flow can erode protective films and increase corrosion best captures what actually happens.