Corrosion Failure Analysis of Copper Tubes in an Export Dehumidifier Evaporator

The failed copper tube in an evaporator for one of dehumidifiers returned from American market were tested to analyze failure reasons by means of inductively coupled plasma atomic emission spectrometer (ICP-AES), universal testing machine, scanning electron microscope (SEM), energy dispersive spectrometer (EDS) and optical microscope (OM). The results show that the failure was due to the expansion of ant nest corrosion from outside to inside on the copper tube, but the rust water produced by corrosion of galvanized steel plate on the evaporator was an important incentive of the ant nest corrosion. It is suggested that the probability of ant nest corrosion should be reduced by changing structural design, controlling production process and raw materials, and trying out new copper alloys that are less sensitive to ant nest corrosion.