Corrosion and degradation behavior of bent aluminum and copper pipes for practical use in air conditioning

Abstract Although copper (Cu) pipes are widely used in refrigerant piping owing to their high thermal conductivity and weathering resistance, there are concerns regarding the increasing price and limited supply of Cu. Consequently, our focus has shifted to aluminum (Al), which is relatively abundant and inexpensive, to investigate its application in refrigerant piping. We previously examined corrosion factors on both the internal and external surfaces of straight piping and conducted accelerated degradation tests, showing that Al has a durability comparable to that of Cu. However, bending sections are always used in addition to straight pipes, and bending induces tensile stress on the outer side of the bending curvature and compressive stress on the inner side. Notably, stress corrosion cracking may occur under tensile stress in corrosive environments. Herein, we investigate the mechanical, electrochemical, and weather resistance properties of bent Al and Cu pipes to evaluate the practicality of Al refrigerant piping.