A pre-assembled insulated weld backing ring for a tubular section of the pipeline. The weld backing ring includes a metal cylinder and an insulation layer. The metal cylinder has a ring-shaped anterior portion and a ring-shaped raised posterior portion with a step therebetween. The posterior portion has a larger diameter than the anterior portion to define an insulation pocket. The insulation layer is positioned on the external surface of the metal cylinder. The insulation layer is made of an insulated material positioned in the insulation pocket to define a protective barrier to protect the tubular section during welding. The weld backing ring may also include a second metal cylinder positioned on the insulation layer. The weld backing ring may be pre-assembled by applying a tubular metal section material to a sheet of metal and rolling the sheet of metal to form the metal cylinder.

The method can include inserting a first portion of a backing device into a fluid aperture of a first conduit component, inserting a second portion of the backing device into a fluid aperture of a second conduit component, and bringing the second conduit component adjacent the first component over the backing device, fusion welding the first conduit component to the second conduit over the backing device, and removing the backing device by circulating a fluid inside the welded conduit components. The backing device can be made of a soluble material.

The method can include inserting a first portion of a backing device into a fluid aperture of a first conduit component, inserting a second portion of the backing device into a fluid aperture of a second conduit component, and bringing the second conduit component adjacent the first component over the backing device, fusion welding the first conduit component to the second conduit over the backing device, and removing the backing device by circulating a fluid inside the welded conduit components. The backing device can be made of a soluble material.

A GTAW system and a welding method suitable for ultra-narrow gaps, and belongs to the technical field of narrow gap welding. The device includes a argon arc welding machine, a GTAW torch, a welding trolley, a wire feeding device, and a gas protection device. The GTAW torch includes a rotating motor, a rotating tungsten, a conductive system, and a gas supply system. The non-axisymmetric rotating tungsten is drived by the rotating motor through the central rotating shaft. The conductive system is used for connecting and supplying electric power from the argon arc welding machine, and the air supply system is used for providing shielding gas into the welding torch. The GTAW torch is fixed on the welding trolley, and the GTAW torch is moved by the welding trolley, and the wire feeding device moves synchronously with the welding torch.

A weld backing tape for double-sided arc welding of double-groove joint preparations. The weld backing tape includes a flexible tape substrate supporting a centrally-disposed heat-resistant material flanked by adhesive material on each side. The weld backing tape is bendable into a folded shape, the heat-resistant material being on the convex side of the fold for seating in a back-side groove of the weld preparation, with an apex of the heat-resistant material substantially packing an apex of the back-side groove to block weld pool material introduced into a front-side groove of the weld preparation. The back-side groove is defined by a pair of side walls extending from the groove apex to a rear surface of the workpiece. The heat-resistant material has a maximum width selected to leave part of each side wall exposed for engagement by the adhesive material to retain the heat-resistant material in position in the back-side groove during welding.

A weld backing tape for double-sided arc welding of double-groove joint preparations. The weld backing tape includes a flexible tape substrate supporting a centrally-disposed heat-resistant material flanked by adhesive material on each side. The weld backing tape is bendable into a folded shape, the heat-resistant material being on the convex side of the fold for seating in a back-side groove of the weld preparation, with an apex of the heat-resistant material substantially packing an apex of the back-side groove to block weld pool material introduced into a front-side groove of the weld preparation. The back-side groove is defined by a pair of side walls extending from the groove apex to a rear surface of the workpiece. The heat-resistant material has a maximum width selected to leave part of each side wall exposed for engagement by the adhesive material to retain the heat-resistant material in position in the back-side groove during welding.

A welding support block supports, from the rear surface of a joint to be welded, a weld pool created during a welding process. The welding support block comprises a block of metal and an outer layer of ceramic material providing a supporting surface. The ceramic material layer has a thickness between 0.25 mm and 1.5 mm. The metal material immediately beneath the ceramic material layer is made of steel. An internal line-up clamp for holding pipes in end-to-end alignment ready for welding may include multiple such welding support blocks. The use of such welding support blocks is particularly useful when laying a sour service carrying pipeline (high H.sub.2S content).

A welding support block supports, from the rear surface of a joint to be welded, a weld pool created during a welding process. The welding support block comprises a block of metal and an outer layer of ceramic material providing a supporting surface. The ceramic material layer has a thickness between 0.25 mm and 1.5 mm. The metal material immediately beneath the ceramic material layer is made of steel. An internal line-up clamp for holding pipes in end-to-end alignment ready for welding may include multiple such welding support blocks. The use of such welding support blocks is particularly useful when laying a sour service carrying pipeline (high H.sub.2S content).

A method of controlling a weld penetration profile on a workpiece (306) having an outer region and an inner region is described. The method comprises the step of applying energy to the outer region of the workpiece with a welder (302) to produce a weld pool (304). The method also comprises the steps of penetrating the workpiece (306) such that the weld pool (304) spans between the outer region and inner region, and also applying a shielding gas to the inner region at a pressure that provides a force that limits weld penetration. A corresponding apparatus is also defined.

A method of controlling a weld penetration profile on a workpiece (306) having an outer region and an inner region is described. The method comprises the step of applying energy to the outer region of the workpiece with a welder (302) to produce a weld pool (304). The method also comprises the steps of penetrating the workpiece (306) such that the weld pool (304) spans between the outer region and inner region, and also applying a shielding gas to the inner region at a pressure that provides a force that limits weld penetration. A corresponding apparatus is also defined.