某GIS设备黄铜三通阀法兰失效分析

某变电站GIS设备黄铜三通阀法兰出现大批量的断裂或开裂现象，易导致SF₆气体泄漏，存在严重安全隐患。文中通过对失效三通阀的宏观形貌、化学成分、金相组织、结构等多方面进行分析、研究，明确了三通阀的开裂原因并提出改进措施。结果表明三通阀法兰材质为铅黄铜，因结构设计及装配方式不当受到较大的周向拉应力，在周围环境含有氧、硫元素的腐蚀性作用下，沿法兰的应力集中区域发生应力腐蚀开裂。

Failure Analysis of Brass Three way Valve Flange in A GIS Equipment

A large number of fractures or cracks occurs in brass three way valve flange of GIS equipment in a substation, which is easy to cause SF6 gas leakage and has serious safety hazards. Through the analysis and research on macroscopic appearance, chemical composition, metallographic structure, structure of the failed three way valve, the reasons for the cracking of three way valve are clarified and the improvement measures are put forward. Results show that the flange of three way valve is lead brass and subjected to large circumferential tensile stress due to improper structural design and assembly method. Under the action of surrounding corrosive environment containing oxygen and sulfur elements, stress corrosion cracking occurs along the stress concentration area of the flange.