摘要
某核电机组二级疏水箱正常疏水阀1GSS171VL阀杆断裂,导致机组被迫降功率运行。为明确失效原因,本文采用宏观分析、化学成分分析、硬度测试、显微组织检验结合拉伸及冲击性能测试的方法对阀杆进行检测,并同步分析阀门内件磨损情况。结果表明:阀杆基材的化学成分、拉伸及冲击性能均符合标准要求;但断裂位置存在补焊痕迹,其外圈显微组织为奥氏体+铁素体,硬度低于标准值,形成强度薄弱点。此外,阀门长期处于闪蒸工况,频繁调节导致碟簧磨损,压缩量不足,进而引发先导阀与主阀芯持续撞击,产生交变应力。最终,补焊薄弱点在长期交变应力作用下发生断裂。本研究为类似阀门的选型优化与维修提供技术参考。
The valve stem of the normal drain valve 1GSS171VL in the secondary drain tank of a nuclear power unit fractured,forcing the unit to operate at reduced power.To identify the cause of the failure,the valve stem was tested by means of macroscopic analysis,chemical composition analysis,hardness testing,microstructure examination,combined with tensile and impact performance testing,and the wear condition of internal valve components was analyzed simultaneously.The results show that the chemical composition,tensile and impact properties of the valve stem base material all meet the standard requirements;however,there are repair welding traces at the fracture location,and the microscopic structure of its outer ring is austenite+ferrite,with hardness lower than the standard value,forming a strength weak point.In addition,the valve was in a harsh flashing condition for a long time,and frequent adjustments led to the wear of the disc spring and insufficient compression,which further caused continuous impact between the pilot valve and the main valve core,generating alternating stress.Finally,the repair welding weak point fractured under the action of long term alternating stress.This study provides a technical reference for the selection optimization and maintenance of similar valves.
作者
方力
胡则栋
朱平
FANG Li;HU Ze-dong;ZHU Ping(CNNP Operation Maintenance Technology Co.,Ltd.,Hangzhou 310000,Zhejiang,China;CNNP Operation and Management Co.,Ltd.,Jiaxing 314300,Zhejiang,China)
出处
《阀门》
2026年第1期101-106,共6页
Chinese Journal of Valve
关键词
阀杆断裂
失效分析
闪蒸工况
补焊
valve stem fracture
failure analysis
flashing condition
repair welding
