Pitting Corrosion of Copper Soft Tubes in Well Water

Pitting corrosion of copper soft tubes has been experienced in the pass-through plumbing system using well water. Although the morphology of the pitting was similar to type 1 pitting corrosion of copper tubes, the quality of well water was different from those in plumbing system. The factor of the pitting corrosion has been investigated by field test in actual plumbing system. The free carbon dioxide in well water was 17 to 20ppm. The presence of both carbon film on the copper tubes and free carbon dioxide in well water caused the pitting corrosion. The pitting corrosion of copper tubes occurred under the presence of both residual ferr carbon more than 5mg/m2 and free carbon dioxide more than 15ppm.