Which measures are effective for preventing internal corrosion in pipelines?

• A. Internal coatings and adequate flow velocity.
• B. Low flow velocity and no coating.
• C. High flow velocity and no protection.
• D. No treatment.

Answer: (C)

Preventing internal corrosion relies on both protecting the metal surface and keeping the fluid moving so that corrosive species don’t linger near the metal. The most effective approach is to apply an internal coating to create a physical barrier between the metal and the fluid, and to maintain an adequate flow velocity that minimizes stagnant zones and helps wash away deposits. When the coating is intact, it greatly reduces the chemical attack; the right flow rate ensures protective films don’t form deposits and that corrosive species don’t accumulate at the surface. Relying on flow alone without a protective barrier is risky because high flow can erode any protective film and still cause corrosion if the surface is exposed. Low flow without coating promotes stagnation and deposits, accelerating corrosion. No treatment leaves the metal fully exposed to the fluid, guaranteeing corrosion.