Which description corresponds to Stage 3 corrosion condition?

Which description corresponds to Stage 3 corrosion condition?

• A. Metal sound. Light rust or flash rust. (Bubbling of paint)
• B. Metal sound. Heavy Rust with and/or light pitting
• C. Metal unsound. Heavier rust and pitting. (Scaling)
• D. Metal unsound. Extensive rust and heavy pitting with holes in metal throughout.

Answer: (C)

Stage 3 corrosion is when the metal has lost its structural soundness due to advancing attack. The best description is metal unsound with heavier rust and pitting, and scaling. Here, rust and pits are more severe than in earlier stages, and the surface is starting to lift with flakes of corrosion products (scaling), signaling deeper penetration into the metal. This differs from the earlier stage, where the metal remains sound even with rust, and from the final stage, where extensive rust, heavy pitting, and holes would be present.

Stage 3 corrosion is when the metal has lost its structural soundness due to advancing attack. The best description is metal unsound with heavier rust and pitting, and scaling. Here, rust and pits are more severe than in earlier stages, and the surface is starting to lift with flakes of corrosion products (scaling), signaling deeper penetration into the metal. This differs from the earlier stage, where the metal remains sound even with rust, and from the final stage, where extensive rust, heavy pitting, and holes would be present.