Device for welding pipe branches and extensions

A device for welding pipe branches and extensions to a main pipe from inside the main pipe, the device including a frame and a frame cylinder, an elongated electrode shaft having a longitudinal central axis, around which the electrode shaft is rotatably arranged, a rotator disc of the electrode shaft, through which the electrode shaft is able to slide axially, an electrode holder in the end of the electrode shaft, an electrode fastened to the holder, a welding jig for supporting the main pipe in the welding station, a fastening element of the welding jig, a rotating element of the welding jig, to which the fastening element is fastened and which is rotatably bearing-mounted inside the frame cylinder such that the rotational axis of the welding jig combines with the central axis of the electrode shaft, characterized in that the welding jig has a support bracket for the main pipe, by which the main pipe is to be supported in the station, in which the central axes of the main pipe and the electrode shaft are combined, that the welding jig has, surrounding the electrode shaft, an adapter piece, to which is connected a shielding gas channel, the shielding gas being adapted to be guided through the adapter piece into the main pipe, and through it, also into the pipe branch or extension to be welded, when the main pipe, or the pipe extension to be welded to the main pipe, or a shielding gas pipe surrounding the main pipe rests against the adapter piece, and that the rotator disc of the electrode shaft is equipped with a locking device, with which the electrode shaft is to be locked axially immobile in relation to the rotator disc.