急冷油／稀释蒸汽换热器管子的腐蚀失效分析

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Several failure resulted from corrosion perforation occurred in tubes in heat exchanger have found in inspection in one petrochemical cooperation. The eddy current examination for tube bundle in heat exchanger was carried out. By using direct spectrum meter and 3-D microscope, the material of failed tube and concave surface were observed and examined. The composition of process water was also examined by using ion chromatogram meter and mass spectrum meter. Then, the broken edge and the hollow in tubes were analyzed from the observation of micro-surface and the analysis of the composition micro zone. It was shown that the cause of failure was resulted from calcium corrosion with local calcium congestion at concave zone and under scale. And the formation of alternate calcium and acid corrosion and the acid corrosion under scale may be other causes of the failure.某石化公司换热器在检验中发现管子多起腐蚀穿孔而失效。对换热器换热列管进行了涡流检测，采用直读光谱仪和三维体视显微镜（3DSM）等对失效管子材质及凹坑形貌进行了检验和观察，利用离子色谱分析仪（IC）和质谱分析仪（MS）等对工艺水介质进行了成分检测，并用扫描电镜（SEM）与能谱分析仪（EDS）对失效管破口和凹坑进行了微观形貌观察及其微区成分分析，结果表明：换热器管子失效是碱在管子表面凹陷处或垢下局部聚集浓缩局部碱腐蚀，并在酸碱交替腐蚀作用形成，也可能还存在垢下的酸腐蚀。