What indicates internal CO2 corrosion?

What indicates internal CO2 corrosion?

• A. Rough pitting across wall
• B. Uniform scaling
• C. Smooth grooving of pipe wall
• D. Delamination

Answer: (C)

Internal CO2 corrosion tends to produce a uniform, steady loss of metal rather than breakouts of rough pits. When CO2-saturated water forms carbonic acid, the attack occurs fairly evenly across the inner surface, often showing up as a smooth groove or thinning running along the pipe wall. This smooth grooving reflects consistent metal loss with a relatively uniform surface, rather than jagged pits or scalloped areas. Rough pitting across the wall would indicate localized attack from other causes (like impurities, H2S, or microbiological factors). Uniform scaling suggests a protective mineral layer forming on the metal surface, which reduces or halts corrosion rather than indicating active internal corrosion. Delamination points to coating or insulation failures rather than the corrosion pattern inside the pipe. So, the presence of a smooth grooving of the pipe wall is the best indicator of internal CO2 corrosion.

Internal CO2 corrosion tends to produce a uniform, steady loss of metal rather than breakouts of rough pits. When CO2-saturated water forms carbonic acid, the attack occurs fairly evenly across the inner surface, often showing up as a smooth groove or thinning running along the pipe wall. This smooth grooving reflects consistent metal loss with a relatively uniform surface, rather than jagged pits or scalloped areas.

Rough pitting across the wall would indicate localized attack from other causes (like impurities, H2S, or microbiological factors). Uniform scaling suggests a protective mineral layer forming on the metal surface, which reduces or halts corrosion rather than indicating active internal corrosion. Delamination points to coating or insulation failures rather than the corrosion pattern inside the pipe.

So, the presence of a smooth grooving of the pipe wall is the best indicator of internal CO2 corrosion.