Pipeline butt joint circumferential weld protective gas sealing device

The utility model relates to a pipeline butt joint circumferential weld protective gas sealing device which comprises two sealing assemblies which are placed in an inner cavity of a pipeline when used and arranged on the two sides of a weld on the pipeline respectively. Each sealing assembly comprises a sealing baffle arranged in the pipeline, and an annular sealing groove is formed in the side wall of each sealing baffle; the self-tightening sealing ring is nested in the annular sealing groove, and the outer wall of the self-tightening sealing ring is in contact with the inner wall of the pipeline; the inflating assemblies are arranged on the sealing assemblies, communicate with the sealing grooves and are used for inflating and pressing the sealing grooves; first protective gas stored in the inflation assembly is introduced into the sealing grooves in the sealing baffles, so that the self-tightening sealing rings nested in the sealing grooves expand in the radial direction, and sealing between the self-tigh