核级承压设备密封结构的有限元分析

Finite element analysis of the flange sealing structure in the reactor system

在AP1000反应堆系统中,很多设备具有承压的功能,其密封性能直接关系到系统能否正常运行,因而密封失效是较之弹塑性失效、疲劳失效等更为基本的失效形式。在ASME规范中采用的密封结构设计方法是华脱尔斯法,此方法采用了一些保守的经验和假设,无法对密封结构处的变形和应力进行细致的计算。本文采用ANSYS有限元分析软件对核承压设备典型的密封结构进行了建模计算,提出了在有限元模型中螺栓预紧力和垫片的等效处理方法,能够对密封结构处垫片的回弹量、法兰的变形及应力分布进行预测。模型分析了采用华脱尔斯法进行密封设计时的设计余量,得到了垫片回弹量与设备内压之间的关系,对于核级承压设备密封结构的设计具有一定的借鉴意义。

Background： In the APIO00 Reactor system, many devices sustain the pressure. Purpose： The sealing function of these devices is essential to ensure the structural integrity of the reactor system. Methods： In the ASME code, Waters method is adopted for the design of sealing structure. Although Waters code is very reliable, it can＇t show the details of the deflection and stress distribution of the sealing structure under pressure. In this paper, a finite element method is developed to evaluate the typical sealing structure. The preload of the bolt and the spring back behavior of the gasket are also simulated by a proposed equivalent method. Results： With the finite element model, the spring back of the gasket, the deflection of the flange and the stress distribution of the sealing structure are predicted. Conclusions： Finally, The quantitative correlation between gasket spring back and inner pressure of the device is obtained, which provide a useful reference for the design of the sealing structure.