The changing type of globe valve for class 1 components of nuclear power unit involves massive pipeline welding. During the overhaul of Fanjiashan nuclear power unit 1 and 2,the automatic welding is used to achieve the changing type of 56 manual globe valves. Due to strict weld quality requirement and short construction period,the changing type of globe valve has become a huge challenge. The quality control points of automatic welding construction on site are summarized,and it is pointed out that elaborate construction and comprehensive technological explanation are key to ensuring valve pipeline welding. For the purpose of the good quality of welding,the reasonable and practical operation guidance,technological explanation and quality control measures are established,which provides valuable experience for automatic welding of pipeline for nuclear power plant.