基于有限元的高温再热蒸汽管道焊缝应力优化分析

Optimization Analysis of Weld Stress in High Temperature Reheated Steam Pipeline based on Finite Element

通过对某电厂670 MW机组的高温再热蒸汽管道大厚壁三通管件焊缝开裂失效原因进行分析,发现焊缝结构偏离设计尺寸产生应力集中为焊缝失效的主要原因。通过对失效焊缝的结构进行优化设计,采用有限元应力分析法对焊缝处的应力分布进行合理计算,精确指导现场无损检测技术、支吊架调整技术,实现了焊缝结构优化前后应力峰值从295.55 MPa降低到112.64 MPa,降幅比例达到162.38%,同时也满足了材料第三强度理论的校核要求,为机组的安全运行提供了可靠的安全状态风险评价。

Based on the analysis of cracking failure caused by large-thick wall tee fittings of the high-temperature reheat steam pipe of a 670 MW unit in a power plant, it is found that the stress concentration of the weld structure deviating from the design size was the main reason for the failure of weld. Through the optimization design of the structure of the failed weld, the finite element stress analysis method was used to reasonably calculate the stress distribution at the weld, and the on-site non-destructive testing technology and the support and hanger adjustment technology was accurately guided, and then the peak stress before and after the optimization of the weld structure was reduced from 295.55 MPa to 112.64 MPa,and the reduction ratio reached 162.38%. At the same time, the verification requirements of the third strength theory of materials was met, and a reliable safety status risk assessment for the safe operation of the unit was provided.