换热器腐蚀失效分析

在换热器定期检查的过程中，发现在换热器表面出现明显的缺口，从而导致换热器失效，为了研究换热器失效的原因，并防止此类事件再次发生，故采用金相分析、SEM和电化学方法对产生腐蚀穿孔的换热器E-715管板焊缝进行失效分析，研究了其腐蚀机理. 结果表明，换热器腐蚀穿孔是由于电化学腐蚀造成的，焊缝电极电位较低，母材电极电位较高，在服役介质中形成原电池，对焊缝造成腐蚀，并最终穿孔. 同时管程介质为烃类，碳含量较高，管体表面产生了渗碳.

Corrosion failure analysis for heat exchanger

During the process of periodic inspection of the heat exchanger, it can be found obvious gap in the surface, which leading to failure of the heat exchanger. In order to investigate the reasons of the failure and keep such incidents from happening again, Metallographic analysis, SEM and electrochemical corrosion perforation are used for E-715 heat exchanger tube sheet weld failure analysis in order to be familiar with its mechanism. It turns out that the heat exchanger corrosion perforation was caused by the electrochemical corrosion. The electrode potential of base metal is higher than that of welding in the service medium which caused the corrosion of welding and final perforation. Meanwhile, the tube medium is a hydrocarbon with a higher carbon content in which the tube surface performed carburization.