Abstract: The method comprises a first-run weld performed from the outside without pads for backing the weld pool, which is obtained by: preparing a welding bevel (C) having a closed bottom by arranging, so that they are mutually adjacent, two pipe segments (T-T′) having symmetrical welding bevel half-profiles (p-p′) with respective annular abutment surfaces (sp-sp′) which are meant to form, by arranging them mutually adjacent so as to obtain front contact, the closed bottom of the welding bevel (C), the closed bottom being further delimited by a groove (SV) which has a maximum chord of preset width (H); performing the first welding run with one or more welding torches which are supplied with a welding wire whose diameter “d” is dependent on the maximum chord (H) of the bottom groove (SV) of the welding bevel (C); maintaining, during the first welding run, the welding arc at a controlled length, by relating the distance (h) between the end of the welding wire and the vertex of the bottom g

Abstract: The system comprises: a distance sensing device for sequentially acquiring, during the welding process or before it, individual transverse profiles of the welding gap by gauging its various depths; electronic units for parametrically reconstructing, by combined numeric and vector calculation, the parametric and topological features of the welding gap starting from the various depths acquired by gauging points; electronic circuits that are adapted to compare the features of the acquired welding gap profile and the stored features of the profile of a corresponding nominal ideal welding gap and to infer corresponding data for varying the parameters of the welding process; and control subsystems using, selectively or in combination, one or more of the variation data to adapt corresponding welding parameters.

Abstract: In a method for welding together pipe ends of pipes held mutually in line the welding process is automatically controlled subject to the angular distance traversed by the welding lance.

Abstract: In a device for welding together pipe ends of pipes held mutually in line, a fixing band is first clamped around a pipe and a ring frame for opening and closing is then arranged therearound which is provided with a guide rail for guiding at least one welding carriage along the periphery of a ring weld.

Abstract: For internally supporting the annular weld during welding together of two pipe ends of two pipes extending mutually in line a weld supporting ring is used consisting of ring pieces comprising at least one supporting body of ceramic material bounding the outer periphery of the weld supporting ring.

Abstract: A device for the back support of the first run weld in the automatic butt-welding of two pipes held together by the two circumferential facing sets of radial pistons of an internal connection. The connector includes a set of independent copper pads of trapezoidal shape disposed in the form of a ring and fixed, with their bases alternately inverted, on a corresponding underlying set of pad support elements idly supported by respective horizontal pins rigid with support blocks which are resiliently supported by one of said circumferential sets of radial pistons of said internal connector by means of radial thrust springs. The pads are kept resiliently and constantly pressed against each other in the manner of a ring along their inclined sides by respective horizontal thrust springs supported by said horizontal pins and acting alternately on opposite faces of said pad support elements.