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According to China's long-distance pipeline construction of the development process, long-distance gas pipeline to the increasingly large-caliber, high-pressure transmission direction. Large-diameter pipe to the welding technology in the construction of pipelines is an important part of effective control points and welding operation in the welding process should pay attention to the issues is to improve the quality of welding an effective way. This paper summarizes the welding technology, to the entire cellulose-based, hybrid, under the composite of three hand-welding technology to protect and gas activity, since the flux-cored wire under the protection of two semi-automatic to fully automatic welding technology and the protection of gas welding and Automatic flux-cored welding technology, to the technological features, the next to the merits of welding technology, welding technology, to welding defects and preventive measures and Shanghai in China's West-East Gas Pipeline o