Pitting corrosion of copper coiled tubes has been experienced in the air conditioning system havingthe open heat storage water tank. Although the morphology of the pitting was similar to type 1 pittingcorrosion in plumbing copper tubes, the quality of circulating water in the system was different fromthose in plumbing system and the inner surface of corroded tubes was fully covered with corrosionproduct of galvanized steel tubes in the air conditioning system.The factor of the pitting corrosion has been investigated by field test in above actual airconditioning system. The circulating water was more corrosive and contained the fine corrosion-product particles of galvanized steel. The presence of both carbon film and corrosion product ofgalvanized steel on the copper tubes caused the pitting corrosion. As the pitting corrosion was muchinfluenced by fine corrosion-product particles of galvanized steel rather than carbon film on innersurface of copper tube, pitting corrosion was reduced by entrapping the fine corrosion-productparticles of galvanized steel in circulating water with fine mesh filter.
展开▼
