Abstract: The welding device including an adjustable connecting assembly includes a fastening mechanism (12), having a cylindrical part (12a) to be introduced into a tube (6) of a network, and a jack (12b) for actuating the cylindrical part (12a), and a welding head (11) including a centering bush (28) to be introduced into the tubular piece (8) to be welded and a welding electrode (26) mounted rotatably about the axis of the bush (28). The fastening mechanism (12) and the welding head (11) are connected by means of the adjustable connecting assembly (13) allowing relative translational movements of the welding head (11) in relation to the fastening mechanism (12) in the direction of the perpendicular common to the axis of the cylindrical part (12a) and to the axis of the bush (28) and relative rotational movements about two perpendicular axis (21, 22), one of which is parallel to the direction of translational movement (18).

Abstract: The drive mechanism for driving the welding head (17) in rotation in the tube is arranged in a motor casing (18) inserted between first and second sections (16a, 16b) of a flexible tubing. The translational movements of the welding head (17) for positioning it in the tube (3) are provided by the sections (16a) of the flexible tubing. The transmission of rotation between the drive mechanism and the welding head (17) is provided by a flexible transmission member arranged in the second section (16b) of the flexible tubing. The device is intended in particular for welding a small repair liner at any height in a steam generator tube of a pressurized-water nuclear reactor.