某批进口燃气炉在投入使用后不久总数中约有1/3炉中的304L不锈钢换热管出现漏水现象; 通过观察换热管的烧损及结垢情况、裂纹及断口形态, 检测其显微硬度和化学成分, 确定了换热管的开裂性质及原因。结果表明: 燃气炉换热管的开裂为应力腐蚀导致的脆性开裂; 循环系统水质、循环不良或补水过多导致管内沉积了大量含酸性腐蚀元素的水垢是换热管开裂的根本原因; 降低水的硬度, 去除硫、氯离子, 合理循环和补水可以避免泄漏的发生。

Leakage occurred on the 304L stainless steel heat-exchanging pipes accounted 1/3 of the total after import gas furnaces used for a period of service. cracking properties and reasons were identified by observing buming loss, scaling crack, fracture morphology of the heat-exchanging pipe were observed and their microhardness and chemical composition were tested. The results show that the cracking mode of the heat-exchanging pipe was brittle cracking caused by stress corrosion. The basic reason of cracking for heat-changing pipe was a lot of scale deposits comprising acid corrosion elements in the pipe, which caused by the poor water quality or excessive water. This leakage could be prevented by lessening the hardness of water and reducing sucfide, chloridion and reasonable circulation and water replenishing.