蒸汽发生器网格板点焊缺陷分析

Study onTack WeldDefects of Grid Plate on Steam Generator

某核电蒸汽发生器二次侧干燥器框架用网格板点焊焊缝出现气孔、裂纹及开裂缺陷。经过分析,产生缺陷的根本原因是蒸汽发生器供应商焊接人员操作不当,部分点焊焊缝熄弧过快,熔池快速凝固和收缩形成收弧弧坑,且焊后未对收弧弧坑进行处理。供应商针对缺陷问题制定解决方案,经过各方审核后在现场进行修复,保证蒸汽发生器网格板点焊焊缝的性能,确保蒸汽发生器运行可靠。同时,供应商在厂内进行全面的经验反馈和总结,对特殊工艺人员的管理和要求得到加强,相关焊接工艺和检验文件得到完善,使后续设备的制造质量得到提高。

The porosity,flaw and crack defects found in the tack welds of grid plate used for the frame of dryer in the secondary side of steam generator in the nuclear power plantwere analyzed in this paper.The root causes of the defects were identified due to the improper operation of the welding personnel of the supplier of steam generator,i.e.the arc craters caused by excessive fast arc extinguishing of some of the tack welds,the quick solidification and shrinkage of molten pool and the poor treatment of craters after the completion of welding.The supplier conducted the corrective actions for the defect repair on site after the review and approval by relevant partiesto ensure the properties of tack welding of grid plate of steam generator and reliable operation performance of steam generator.Meanwhile,the feedback and summary of comprehensive experiencesand lessonswas conducted in the plant by the supplier in order to strengthenthe management and requirements of operation personnel for the special technological processes,enhance the relevant welding process and inspection documents and improve the fabrication quality of subsequent equipment.