Abstract: An internal chuck for use in the butt welding of tubes 16, 17 aligning the tubes and for bringing them into abutment comprises a central tube 6, a sleeve 7 slidable on the central tube and carrying centering means 12 and welding backup means 8, the centering means and the welding backup means being longitudinally spaced from one another, gripping means 2, and jaws 33 for clamping against the tubes. The jaws are displaceable longitudinally relative to the gripping means and central tube to draw the two tubes together and a jack 27 is provided for displacing the sleeve longitudinally relative to the central tube so that either the centering means or the welding backup means can be aligned with the ends of the tubes.

Abstract: Apparatus for supporting a tubular element 24 to be butt joined horizontally at one of its ends to a tubular structure 27, comprises an upwardly acting, vertical hydraulic thrust jack 9 which compensates at least partly for the weight of the tubular element and which is placed towards the other end of the tubular element. The thrust jack is pivoted at its upper end on a slide 11 which is vertically movable and carries support members 23 for supporting the tubular element, and at its lower end on a base 6 mounted on a lower frame 2 provided with wheels 3 adapted to run on rails 4.

Abstract: An external apparatus for butting two tubular elements 1, 2 to be welded together comprises two frames 8, 9 provided with means for the external gripping of the elements and which are connected by jacks 10, 11 for bringing the elements together and by a plurality of connecting and aligning means 14-19 each comprising a pair of members 20, 21 engageable one in the other with the interposition of an elastic means 22. The gripping means comprise a plurality of radial jaws 55-64 for gripping the tubular elements and carried by support rings each comprising three jaw holders 23-25 each in the form of a segment of a circle.

Abstract: A machine for the internal butt welding of two tubes comprises a fixed axial electron gun, a rotary prism system for radially deflecting the electron beam and comprising a plurality of prisms and a deflection system for cyclically delivering the electron beam emitted by the electron gun successively to each of the prisms at a high frequency, the relative duration of utilization of each prism being modifiable in the course of the rotation of the rotary system.