Corrosion of Copper Tubes for Air Conditioning System Using Well Water at an Eco–Friendly Facility

Abstract

Recently, the leakage was experienced for copper tubes of air conditioning system using well water by corrosion after about seven years services. The corrosion in copper tubes experienced in the outdoor unit of a water–cooled packaged air–conditioner system was localized and penetrated through the tubes thickness. It was inferred that the corrosion was sand erosion due to the fast flow of water and the breakdown of the oxide film caused by the sand. In addition, corrosion in copper tubes was experienced near the heat affected zone at brazed joints of u–bend tubes and connecting tubes for desiccant air–conditioning heat exchangers. This corrosion was considered to be galvanic groove corrosion in brazing part or Type I pitting corrosion, which occurs in a well water environment, because of the potential difference between copper and brazing material in the former and the presence of small mounds of patina products in the latter. It was considered necessary to install sand removal equipment and to change to use the materials with high corrosion resistance.