某炼厂常压塔顶全焊接板式换热器（材质ASTM SMO254)，在使用约半年时间即出现大面积腐蚀穿孔。从现场情况看，换热器常顶油气侧入口焊接面结垢严重，出现大面积铵盐沉积,清洗后发现，垢下发生严重腐蚀，甚至穿孔。本工作从工艺防腐蚀和换热器内部结构等方面对腐蚀原因进行了分析。结果表明:由于注水量的不足，导致铵盐在换热板表面结垢，同时“一脱三注”的不稳定，导致了严重的垢下腐蚀。

Perforation corrosion occurred in the tube sheet of plate heat exchanger in an atmosphere overhead condenser after service for half a year. The material of the tube sheet is ASTM SMO254. Severe scaling occurred on the surface of the plate of the heat exchanger and some ammonium salt was deposited. Severe corrosion, even perforation, was observed after cleaning the scale. The failure reason was analyzed in the view of the anti-corrosion technology and the constructure of the heat exchanger. The results show that the lacking of the water injection generated the deposition of the ammonium salt and the corrosion happened under the deposit, the instability of the technology also had some influence on the corrosion.