某型号卧式蒸汽锅炉在使用1 a(年)后, 其底板产生了贯穿裂缝, 导致泄漏。经宏观观察、化学成分分析、金相检验以及能谱分析等方法对锅炉底板泄漏原因进行了分析。结果表明: 该锅炉裂缝是一种垢下闭塞电池腐蚀裂纹; 产生裂缝的主要原因是锅炉结构设计不当, 造成封闭区域, 并且使用未经预处理的原水, 从而导致局部区域沉积大量的CaCO3水垢; CaCO3水垢的大量沉积, 阻碍了O2的正常流动, 造成氧的浓度梯度, 使垢下区域和暴露区域形成闭塞电池, 导致垢下区域钢材快速腐蚀, 从而形成裂缝泄漏。最后提出了避免垢下腐蚀裂纹的预防措施。

Cracks which penetrating through the boiler bottom and leakage were found for a horizontal steam boiler after being used for about one year, and the leakage reasons of the boiler bottom were analyzed by means of macro observation, chemical compositions analysis, metallographic examination, SEM observation and energy spectrum analysis. The results show that the boiler cracks were considered to be the under-deposite occluded cell corrosion cracks. The main cause of the cracks was the small enclosed area resulting from the poorly designed structure of the boiler. It led to local deposition of CaCO3 scale with using un-pretreated raw water. Lots of CaCO3 scale deposition hindered the normal flow of O2, causing the oxygen concentration gradient, thus the scale region and the exposed region formed occluded cell which led to rapid corrosion of steel under the scale thereby forming crack leakage. Finally, preventive measures were proposed to avoid the under-deposit corrosion cracks.