PIPE RESISTANCE BUTT WELDING APPARATUS

A pipe resistance butt welding apparatus disposable within the pipes to be welded comprises a fixed expanding clamp and a movable expanding clamp, provided with clamping elements and actuating cylinders and intended to fix the pipes to be welded with respect to the apparatus. A cylinder to effect an axial movement of the movable expanding clamp is installed at the end at which this expanding clamp is located; said axial movement provides for drawing together the ends of the pipes to be welded in the course of fusion and upsetting. The cylinder for the axial movement of the movable expanding clamp is coupled with the actuating cylinder of the same clamp and with the clamping elements. The devices making up the apparatus and the cylinders are coaxially installed within a body wherefrom the clamp elements extend outwardly to engage the inner surface of the pipes being welded. Modifications of the apparatus for weld-joining of medium and large diameter pipes respectively are also described.