热电部6号锅炉水冷壁炉管开裂原因分析

CAUSE ANALYSIS ON THE TUBE CRACKING OF THE WATER WALL 6 # BOILER OF THERMOELECTRIC DEPARTMENT

热电部锅炉水冷壁的炉管发生开裂失效。装备研究院对开裂炉管进行了宏观检验、壁厚测定、化学成分分析、金相组织检验、硬度检测、力学性能试验、扫描电镜检验及水质分析,认为水质超标是腐蚀和结垢形成并快速发展的主要因素,管内壁酸洗未形成有效的保护膜,是腐蚀发生的诱因;两者共同作用导致炉管向火面焊缝附近产生材质劣化、裂纹和壁厚减薄,使得炉管在工作压力下产生应力腐蚀,最终发生开裂。结合失效原因向生产厂提出了有针对性的建议。

Cracking failure occurred in the furnace tube of the boiler water-wall of the Thermoelectric Department.After the Equipment Research Institute has carried out macroscopic examination,wall thickness determination,chemical composition analysis, microstructure examination,hardness test,mechanics performance test,scanning electron microscopy(SEM)and water quality analysis,it was considered that the over-standard water quality was the main reason for the forming of corrosion and scale buildup and fast development;the pickling of the inner pipe not shaping effective protective membrane was the inducement of the corrosion.These two factors worked together and led to the deterioration of materials around the weld facing the fire in the furnace tube, cracking and thinning of the wall thickness.Hence, stress corrosion appeared in the furnace tube under working pressure and eventually cracking occurred. Combining with the failure reasons,the paper puts forward some pertinent suggestions for the factory.