某600MW机组再热器防磨罩固定焊点产生裂纹原因分析

某电厂锅炉投产后首次大修水压试验过程中,低温再热器至高温再热器过渡段管子发现多处漏点,漏点都在管子与防磨罩的焊接处,扩大性检查发现存在大范围该种现象.对照规程及设计参数,对母管及防磨罩材质和焊条材质进行材质分析,同时对现场存在裂纹的管子进行焊接工艺分析,发现普遍存在收弧点弧坑现象.分析结果认为导致裂纹产生的主要原因为防...

Analysis on the Cracking Causes of the Fixing Welding Point of Reheater Wearing Casing in a 600 MW Boiler

A few leakage points were located at the welding point between the reheater’s transitional pipe and wearing casing by water pressure test during a boiler’s first overhaul and many more leakage were founded by extended inspection. An inspection analysis is conducted on the material quality of pipes, wearing casings and welding rods, and on the welding process of the cracked pipes by referring to the relevant codes and design parameters. It was found that craters commonly exit at the welding arc points. The main causes for the cracking are that the welding joints between the wearing casing and pipe is too long, which leads to large stress induced by differential expansion of different materials; that the craters at the welding arc points lead to the cracks extending into base metal and that the welding material does not conforms with relevant regulations.