Pipeline welding auxiliary device

The utility model provides a pipeline welding auxiliary device, relates to the technical field of fire-fighting pipelines, and solves the technical problems that residual water in the fire-fighting pipelines is difficult to discharge, the operation is difficult when the pipelines are welded with flange joints, and the welding quality is influenced. The pipeline welding auxiliary device comprises a drainage tube and an air bag part, and the air bag part is fixed to the outer wall of the drainage tube and surrounds the drainage tube by a circle; the pipe diameter of the drainage pipe is smaller than that of a to-be-welded pipeline, the air bag part has an expansion state and a contraction state, the auxiliary device extends into the to-be-welded pipeline, and when the air bag part is in the expansion state, the air bag part can fill a gap between the to-be-welded pipeline and the drainage pipe, so that residual water in the to-be-welded pipeline flows out of the drainage pipe. According to the auxiliary device,