锅炉水冷壁连通管泄漏原因分析

Analysis on Cause of Leakage of Communicating Pipe of Boiler Water-cooled Wall

某电厂1号锅炉水冷壁连通管尺寸为?60 mm×6.5 mm,材料为20G钢,在运行中发生泄漏。对泄漏的连通管进行了宏观检查、金相检验和硬度测定。结果表明:连通管焊缝热影响区有魏氏组织且硬度较高,从而产生较大的硬度梯度和内应力,在因水冷壁的挤压而产生的过大的弯曲应力的作用下,最终导致其开裂而泄漏。

A communicating pipe 60 mm in outer diameter by 6.5 mm wall thickness for boiler No.1,made from 20 G steel,leaked in operating in a power plant.The leaking communicating pipe was tested for appearance,microstructure,and hardness.The results indicated that the communicating pipe exhibited Widmannstaetten structure and having higher hardness,and thereby developed larger hardness gradient and inner stress in weld zone,and finally,leaked due to cracking by the action of excessive bending stress caused by extrusion of the water-cooled wall.