汽轮机再热调节阀螺栓组失效原因分析

针对某台汽轮机再热调节阀螺栓组出现开裂、断裂、螺纹咬死等多种形式的失效问题,从螺栓材质化学成分、力学性能、金相组织及断口检察等方面进行了全面分析。结果表明,螺栓组失效主要由其综合力学性能偏低,以及材质用错、应力增大、预紧工艺不当等所致。对此,提出了大修时对调节阀螺栓进行100%的硬度、超声波检查和全相抽查,选择紧力偏差较低的预紧工艺等建议。

CAUSE ANALYSIS OF BOLT GROUP FAILURE ON REHEATED STEAM CONTROL VALVE OF THE STEAM TURBINE

Directing against the failure problems of bolts on the reheated steam control valve of the steam turbine in one power plant,such as cracking,breakage,and snapping of threads etc.,comprehensive analysis has been carried out from aspects of chemical composition,mechanical performance,and metallorgraphic structure of bolts’ materials,as well as macro-scopic and microscopic observations of the fracture.Results show that the main cause leading to bolt group failure is the lower comprehensive mechanical performance,in addition,the wrong material used,the redistribution of stress,and the improper tightening process etc.,make the bolt failure to be accelerated.For this,corresponding recommendations have been put forward.