±800 kV换流站逆止阀扭转弹簧断裂原因分析

Causes Analysis of Torsion Spring Fracture in Check Valve in ±800 kV Converter Station

某±800 kV换流站换流阀内冷水系统主循环泵出口逆止阀内部扭转弹簧的弹簧臂发生断裂,采用断口宏观检查、化学成分分析、硬度检测、扫描电镜分析、应力计算等手段,对扭转弹簧断裂失效原因进行了分析。结果表明,逆止阀内扭转弹簧失效的主要原因是疲劳断裂和摩擦磨损。扭转弹簧和逆止阀存在的设计缺陷也加速了弹簧失效:在动负荷工作状态下扭转弹簧的局部最大弯曲应力达到许用弯曲应力,容易引发弹簧发生疲劳断裂;逆止阀结构设计不合理,加速弹簧臂摩擦磨损。

For the fractured spring arm of the torsion spring in the outlet check valve of main circulating pump for the converter valve cooling system in a ±800 kV converter station, the causes were analyzed by means of macroscopic examination of fracture, chemical composition analysis, hardness detection, scanning electron microscope analysis and stress calculation. The results show that fatigue fracture and abrasion are the main causes leading to the torsion spring failure in the check valve, and flawed design of torsion springs and check valves also accelerate the spring failure. When the maximum local bending stress of torsion spring is up to the allowable bending stress under dynamic load, fatigue fracture is prone to occur in the spring. In addition, unreasonable structural design of check valve also accelerates abrasion of spring arm.