Abstract: The device for the centering and clamping of pipe workpieces to be welded to another comprises clamping units which have clamping grooves opening outwards in a wedge-shaped manner and each containing a row of clamping members. Their groove walls are formed by annular parts which are movable axially relative to one another, are arranged releasably on a holding body and can be subjected to a force in the direction towards one another. The annular parts limiting a clamping groove are designed as elements separate from the annular parts limiting the other clamping grooves. The annular parts of each clamping unit are connected to one another movably in the axial direction, and there are hollow-cylindrical spacer pieces between the clamping units, one of which defines the welding region.

Abstract: Apparatus for centering and clamping pipe workpieces to be welded to one another, which has, on both sides of a welding zone equipped with an inert-gas supply system, clamping units of which the first comprises at least one clamping device and the second at least two clamping devices. These consist of clamping grooves opening outwards in the form of a wedge and each containing a row of clamping members. Their walls are formed by annular parts movable axially relative to one another. The two outermost of these annular parts are connected releaseably to one another via a pull rod and a drive body, by means of which they can be brought closer to one another counter to a spring-force accumulator and moved away from one another again by means of the spring-force accumulator. The inner annular parts and the welding zone are arranged on a holding body.

Abstract: The device for making a peripheral welding seam on a cylindrical tube (1) is attachable on the tube (1), is equipped with a rotary drive (15) for a rotational movement of the welding tool about the tube axis and is defined in that it has two rotatable rollers (10, 12) fastened to the device and arranged fixedly at a distance from one another in the peripheral direction and a third pivotable drive roller (15) connected to the drive. In the cross-sectional direction of the tube (1), the space between the rollers (10, 12, 15) has a larger dimension than the tube (1). When the dirve roller (15) is partially pivoted away, a lateral insertion orifice for the tube is consequently provided and likewise has larger dimensions than the tube (1).

Abstract: Device for mutually centering and clamping two pipepieces which are to be welded to one another, which device, for each of the workpieces (50, 51), has a clamping unit on both sides of a welding area (9) provided with an inert gas supply (27). Each clamping unit comprises at least one peripheral row of clamping members which are contained in each case in a clamping groove (36, 39, 42), can be stretched outwards or relaxed inwards by mutual axial approach or distancing of the flanks of the clamping groove and have an outwardly pointing clamping surface for the contact with the bore surface of the workpiece. For achieving an easy method of construction and application, it is provided that the axial extent of the clamping members, lined up in large number at a slight distance, is greater than the width of their clamping surfaces in the peripheral direction. They are preferably formed by the coils of a helical spring (3).