Failure analysis of copper pipes used in the heat exchangers in fan coil units
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Date
2023
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Abstract
Heat exchangers (HE) consist of copper and steel pipes and are used for heating and cooling the ambient air. One of the main problems seen in HE is the leakage on copper pipes. In this study, failed and properly working copper pipe samples used for different durations were examined in detail. The microstructural analyses were performed using optical microscopy (OM) and scanning electron microscopy (SEM) to detect corrosion occurrences on copper pipe surfaces. In addition, corrosion products of the samples were defined by X-Ray Diffraction (XRD), Energy Dispersive Spectroscopy (EDS) and Fourier-Transform Infrared Spectroscopy (FTIR) analyses. The formation of interconnected tunnels in cross section of the failed copper pipe sample that were in microscopic dimensions and corrosion products were observed. Consequently, all the analyses result that were obtained from the samples pointed out a corrosion mechanism known as ant-nest corrosion. It was concluded that the main reason of corrosion was related to ethylene glycol type additives which were used in HE along with mains water. © 2023 CSIC.
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Keywords
Additives , Copper corrosion , Copper pipe , Energy dispersive spectroscopy , Ethylene , Ethylene glycol , Failure analysis , Fourier transform infrared spectroscopy , Pipeline corrosion , Scanning electron microscopy , Ambient air , Ant-nest corrosion , Corrosion mechanisms , Corrosion products , Diffraction energy , Fan coil unit , Heating and cooling , Microstructural analysis , Pipe surfaces , X- ray diffractions , Heat exchangers