A gas-shielded arc welding method is disclosed and includes joining steel materials together by narrow-gap multilayer welding. A groove between the steel materials has an groove angle ? of 20? or less, and a root gap G (mm) that is a gap at a lower portion of the groove is 7 to 15 mm. Root pass is performed in one pass using a ceramic-made backing material at a welding current I (A) of 250 to 400 A and a welding voltage V (V) of 25 to 45 V while a value [Q/G] obtained by dividing a welding heat input Q (KJ/mm) computed using a prescribed formula by the root gap G (mm) is controlled within a range of 0.32 to 0.70.

A method for welding two or more conduits includes aligning end portions thereof in an abutting relationship to define a gap. The method includes performing a spatter free root weld along the gap to configure a root layer while the inner circumferential surface side is unobstructed. After the root weld is complete, an outward thrust is applied along the inner circumferential surfaces of the conduits. During the application of the outward thrust, a filler weld is performed along the gap to fill the gap and to facilitate shrinkage of the filler and root weld materials longitudinally and radially outward while preventing pressing out of the filler and root weld materials radially inward of the inner circumferential surface.

A method for welding two or more conduits includes aligning end portions thereof in an abutting relationship to define a gap. The method includes performing a spatter free root weld along the gap to configure a root layer while the inner circumferential surface side is unobstructed. After the root weld is complete, an outward thrust is applied along the inner circumferential surfaces of the conduits. During the application of the outward thrust, a filler weld is performed along the gap to fill the gap and to facilitate shrinkage of the filler and root weld materials longitudinally and radially outward while preventing pressing out of the filler and root weld materials radially inward of the inner circumferential surface.

An arc welding process is disclosed. In one example, the process comprises arranging an electrode at the front of a joining gap formed by joining partners contacted with opposite poles to the electrode; arranging a pair of magnetic poles at the rear or top of the joining gap and substantially centered with respect to the front electrode surface; generating the arc such that the joining partners form a welding zone comprising a weld pool with substantially simultaneous induction of a low-frequency oscillating magnetic field between the pair of magnetic poles; progressively moving the electrode along the joining gap to move the weld pool between the joining partners, leaving behind a weld seam, with synchronous entrainment of the low-frequency oscillating magnetic field. A magnetic flux density of the low-frequency oscillating magnetic field is selected such that an induced Lorentz force supports the weld pool and prevents escape from the joining gap.

An arc welding process is disclosed. In one example, the process comprises arranging an electrode at the front of a joining gap formed by joining partners contacted with opposite poles to the electrode; arranging a pair of magnetic poles at the rear or top of the joining gap and substantially centered with respect to the front electrode surface; generating the arc such that the joining partners form a welding zone comprising a weld pool with substantially simultaneous induction of a low-frequency oscillating magnetic field between the pair of magnetic poles; progressively moving the electrode along the joining gap to move the weld pool between the joining partners, leaving behind a weld seam, with synchronous entrainment of the low-frequency oscillating magnetic field. A magnetic flux density of the low-frequency oscillating magnetic field is selected such that an induced Lorentz force supports the weld pool and prevents escape from the joining gap.

A method for welding two or more conduits includes aligning end portions thereof in an abutting relationship to define a gap. The method includes performing a spatter free root weld along the gap to configure a root layer while the inner circumferential surface side is unobstructed. After the root weld is complete, an outward thrust is applied along the inner circumferential surfaces of the conduits. During the application of the outward thrust, a filler weld is performed along the gap to fill the gap and to facilitate shrinkage of the filler and root weld materials longitudinally and radially outward while preventing pressing out of the filler and root weld materials radially inward of the inner circumferential surface.

A method for welding two or more conduits includes aligning end portions thereof in an abutting relationship to define a gap. The method includes performing a spatter free root weld along the gap to configure a root layer while the inner circumferential surface side is unobstructed. After the root weld is complete, an outward thrust is applied along the inner circumferential surfaces of the conduits. During the application of the outward thrust, a filler weld is performed along the gap to fill the gap and to facilitate shrinkage of the filler and root weld materials longitudinally and radially outward while preventing pressing out of the filler and root weld materials radially inward of the inner circumferential surface.

A welding backing insert (20) includes a body (22), a retention member (24) and an insertion member (26). The retention member (24) includes at least one leg (28) being deflectable to enable insertion into a hollow profile structural extrusions (14). At least one leg (28) tries to return to its original position exerting a force on the hollow profile structural extrusion (14) to retain the backing insert (20) in the hollow profile structural extrusion (14). The insertion member (26) projects from the body for inserting into a second hollow profile structural extrusion (14). A gap-control joint spacer (50) projects from the body to provide a gap between adjacent hollow profile structural extrusions.

A welding backing insert (20) includes a body (22), a retention member (24) and an insertion member (26). The retention member (24) includes at least one leg (28) being deflectable to enable insertion into a hollow profile structural extrusions (14). At least one leg (28) tries to return to its original position exerting a force on the hollow profile structural extrusion (14) to retain the backing insert (20) in the hollow profile structural extrusion (14). The insertion member (26) projects from the body for inserting into a second hollow profile structural extrusion (14). A gap-control joint spacer (50) projects from the body to provide a gap between adjacent hollow profile structural extrusions.

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.