换热器管束腐蚀穿孔失效原因分析

摘要

采用光学显微镜、X射线荧光光谱仪、X射线衍射仪(XRD)、电化学测试等分析手段,对某洗化厂循环水换热器管束钢(20 #钢)进行失效分析.分析结果表明:管束材质成分不符合标准20#钢成分的要求,管束材质的变化将影响其耐蚀性;又由于管束内表面结垢发生较为严重的垢下腐蚀,管束内表面存在氧化铁垢层使垢层内外形成氧浓差电池,构成大阴极小阳极腐蚀原电池.所以,垢下腐蚀是引起管束穿孔的主要原因.%Failure of heat exchanger at a wash of circulating water factory was analyzed by optical microscope, X-ray fluorescence spectrometer, X-ray diffraction (XRD), electrochemical test analysis method. The results show that chemical composition of heat exchanger didn't meet the standard of 20# steel. Due to the surface of the vascular bundles scaling there is a serious corrosion, inside surface of tubes exist iron oxide layer which led to the under-deposition corrosion because different concentration of oxygen inside and outside deposition form corrosion battery. Therefore, under-deposit corrosion is the main the main cause of tubes perforation.