Abstract: A method of laying a pipeline (6) underwater includes the steps of holding an end of a pipeline (6), providing a pipe section (5) for extending the pipeline (6), arranging the pipe section (5) adjacent to the end of pipeline (6) thereby defining a circumferential joint (7) to be welded, and welding the pipes (5, 6) together. A plurality of welding torches (8) move along the circumferential joint (7) and are operated simultaneously to weld the pipes together. The pipes (5, 6) are made of TMCP-SC steel. After the root weld is laid, a cooling ring (1) mounted on an internal clamp inside the pipes (5, 6) sprays cooling liquid, for example a fluid spray of atomised water (10) and air, from nozzles (2) onto an interior surface of the pipes (5, 6) in the region of the circumferential joint (7), thereby cooling the pipes (5, 6).

Abstract: A method of laying a pipeline (6) underwater includes the steps of holding an end of a pipeline (6), providing a pipe section (5) for extending the pipeline (6), arranging the pipe section (5) adjacent to the end of pipeline (6) thereby defining a circumferential joint (7) to be welded, and welding the pipes (5, 6) together. A plurality of welding torches (8) move along the circumferential joint (7) and are operated simultaneously to weld the pipes together. The pipes (5, 6) are made of TMCP-SC steel. After the root weld is laid, a cooling ring (1) mounted on an internal clamp inside the pipes (5, 6) sprays cooling liquid, for example a fluid spray of atomised water (10) and air, from nozzles (2) onto an interior surface of the pipes (5, 6) in the region of the circumferential joint (7), thereby cooling the pipes (5, 6).

Abstract: Two pipes are arranged, when forming a deep sea pipeline, end to end thereby defining a circumferentially extending narrow angled (less than 10 degrees) groove. Two arc welding torches are arranged directly adjacent to each other on a single carriage that moves around the pipes, thereby forming a twin arc welding system. The position of the arc of each torch is independently oscillated between the walls of the groove to form a weld therein. The arcs are guided automatically by an electronic guidance system, wherein electrical characteristics (such as arc current voltage and/or impedance) of the welding of each torch with regard to one of the two pipes are compared with the corresponding electrical characteristics relating to the other of the pipes. The position of an arc of a torch may thus be aligned with the center line of the groove.

Abstract: A welding apparatus, for welding pipe sections (1, 2) together to form an underwater pipeline, is arranged to weld pipe sections (1, 2) together when they are in a generally upright orientation with the bottom of an upper pipe section (2) abutting the top of a lower pipe section (1) that defines the end of a pipeline. The welding apparatus includes a rotary equipment holder (5) mounted for rotation about a generally vertical axis (8) and having a central opening (5A) through which pipe sections (1, 2) are able to pass as a pipeline is laid, a plurality of welding heads (12) angularly spaced about the rotary equipment holder (5), each head (12) being associated with a respective sector of the rotary equipment holder, and a welding head guide assembly (11) for fixing around a pipe section (1). The guide assembly (11) includes a guide track (14) for guiding movement of each of the welding heads (12) around the pipe section (1).

Abstract: A welding apparatus, for welding pipe sections (1, 2) together to form an underwater pipeline, is arranged to weld pipe sections (1, 2) together when they are in a generally upright orientation with the bottom of an upper pipe section (2) abutting the top of a lower pipe section (1) that defines the end of a pipeline. The welding apparatus includes a rotary equipment holder (5) mounted for rotation about a generally vertical axis (8) and having a central opening (5A) through which pipe sections (1, 2) are able to pass as a pipeline is laid, a plurality of welding heads (12) angularly spaced about the rotary equipment holder (5), each head (12) being associated with a respective sector of the rotary equipment holder, and a welding head guide assembly (11) for fixing around a pipe section (1). The guide assembly (11) includes a guide track (14) for guiding movement of each of the welding heads (12) around the pipe section (1).

Abstract: Apparatus (10) and method of forming a deep sea pipeline or a cross country pipeline by welding pipes together to form the pipeline. Two pipes (2, 4) are arranged so that their ends (26, 27) define a circumferentially extending narrow angled (less than 10 degrees) groove (28). At least two arc welding torches (1) are arranged directly adjacent to each other on a single carriage that moves around the pipes, to form a twin arc welding system. The arcs of the torches (1) form a weld (3) in the groove. The carriage is moved around the pipe, the torches thus moving around the pipe with the same speed. Each torch (1) is independently oscillated so that the position of its arc oscillates between the walls of the groove.