A method comprising an arc ignition phase (IP), an arc-stabilizing phase (AP) and a stable arc phase (SP). The arc stabilizing phase comprises an initial sub-phase (IS) comprising the step of feeding at least one hot wire (4, 12) at constant feed speed and a main sub-phase (MS) comprising the steps of feeding said hot wire at constant feed speed and feeding at least one cold wire (22) at constant feed speed. The stable arc phase comprises the steps of continuously adjusting the feed speed of the hot wire and continuously adjusting the feed speed of the cold wire. The invention also relates to a welding apparatus (1) for carrying out the method. The welding apparatus comprises a hot wire feeding means (150), a contact means (2), a cold wire feeding means (35) and a control unit (31). The control unit is adapted to control said hot wire feeding means to feed the hot wire at a constant feed speed during the initial sub-phase, feed the hot wire at a constant feed speed during the main sub-phase and to continuously during the stable arc phase adjust the feed speed of the hot wire. The control unit is adapted to control said cold wire feeding means to feed the cold wire at a constant feed speed during the main sub-phase and continuously during the stable arc phase adjust the cold wire feed speed.

A swing/rotating gas metal arc welding torch, include a hollow shaft motor and a feeder panel. An upper extending shaft of the feeder panel penetrates through a brush mechanism, and is fixedly connected to a lower extension shaft of the hollow shaft by means of a coupling, and a lower extending shaft of the feeder panel penetrates through a support bearing mounted in a brush base and is then connected to an eccentric or bent conductive rod mechanism; the motor base is fixedly connected to the brush base by means of connecting screws, and a welding shielding gas is provided and welding torch cooling is achieved by means of inner holes of the connecting screws as well as a built-in gas passage and a cooling water passage of the brush base; the length of the conductive rod mechanism is adjusted by means of modulation or extension and retraction.

A swing/rotating gas metal arc welding torch, include a hollow shaft motor and a feeder panel. An upper extending shaft of the feeder panel penetrates through a brush mechanism, and is fixedly connected to a lower extension shaft of the hollow shaft by means of a coupling, and a lower extending shaft of the feeder panel penetrates through a support bearing mounted in a brush base and is then connected to an eccentric or bent conductive rod mechanism; the motor base is fixedly connected to the brush base by means of connecting screws, and a welding shielding gas is provided and welding torch cooling is achieved by means of inner holes of the connecting screws as well as a built-in gas passage and a cooling water passage of the brush base; the length of the conductive rod mechanism is adjusted by means of modulation or extension and retraction.

The disclosed technology relates generally to welding technologies and more particularly to electrode assemblies for arc welding, e.g., submerged arc welding. In one aspect, an electrode assembly for submerged arc welding (SAW) comprises a head portion and an extension portion that are arranged serially to feed a consumable electrode therethrough such that, during SAW, the head portion is disposed to be distal to an arcing tip of the consumable electrode and the extension portion is disposed to be proximal to the arcing tip of the consumable electrode. The head portion includes a contact tip configured to electrically contact the consumable electrode to deliver power thereto. The extension portion is formed of a single piece insulating article configured for the consumable electrode to finally pass through before the arcing tip is exposed.

Specific AC welding waveforms are utilized to increase the toughness level of austenitic stainless steel above what is achieved using the same welding consumables using standard DC welding waveforms.

A circumferential welded joint of a line pipe is formed by butting against each other end portions of steel pipes having a yield strength according to 5L Specification of API Standards not smaller than 555 N/mm.sup.2 and welding the butted portions in a circumferential direction. A joint strength ratio σ.sub.match=(TS-w/TS-b).Math.(YS-w/YS-b) represented by a product of a ratio between a tensile strength TS-w of a weld metal and a tensile strength TS-b of a base material and a ratio between a yield strength YS-w of the weld metal and a yield strength YS-b of the base material, and a critical equivalent plastic strain ε.sub.p-cri [%] for ductile crack generation in a base material heat affected zone satisfy Equation (1), and the yield strengths YS-w, YS-b of the weld metal and base material satisfy Equation (2).
σ.sub.match>4.85ε.sub.p-cri.sup.−0.31  (1)
YS-w/YS-b≧1.0  (2)

Cladding strip feeders having independent pressure rollers and strip cladding systems with cladding strip feeders having independent pressure rollers are disclosed. A disclosed example cladding strip feeder for a strip cladding system includes: a drive roller to advance a cladding strip along a strip feed path through contact plates; a first pressure roller positioned along the strip feed path opposite a first section of the drive roller; a second pressure roller positioned along the strip feed path opposite a second section of the drive roller; a third pressure roller positioned along the strip feed path opposite a third section of the drive roller; a first pressure adjuster to set a first pressure applied to the cladding strip by the first pressure roller and the first section of the drive roller; a second pressure adjuster to set a second pressure applied to the cladding strip by the second pressure roller and the second section of the drive roller; and a third pressure adjuster to set a third pressure applied to the cladding strip by the third pressure roller and the third section of the drive roller, the first pressure roller, the second pressure roller, and the third pressure roller being configured to apply symmetric pressure across a width of the cladding strip by selectively setting at least one of the second pressure adjuster to apply the second pressure or the third pressure adjuster to apply the third pressure based on the cladding strip having one of at least three incremental strip widths.

Strip cladding heads having independent strip pressure adjustments and strip cladding systems with strip cladding heads having independent strip pressure adjustments are disclosed. A disclosed example cladding head for strip cladding system includes a first contact jaw, a second contact jaw, and a third contact jaw. The first contact jaw includes first and second contacts to deliver welding power to a cladding strip that is driven between the first and second contacts. The second contact jaw includes third and fourth contacts to deliver the welding power to the cladding strip that is driven between the third and fourth contacts. The third contact jaw includes fifth and sixth contacts to deliver the welding power to the cladding strip that is driven between the fifth and sixth contacts, where the first, second, and third contact jaws selectively provide symmetrical contact with the cladding strip across a width of the cladding strip when the cladding strip has one of at least three incremental strip widths, and the three incremental strip widths correspond to ones of the first, second, and third contact jaws.

Strip cladding heads having strip pressure limits and strip cladding systems with strip cladding heads having strip pressure limits are disclosed are disclosed. A disclosed example cladding head for a strip cladding system includes a first contact jaw comprising first and second contacts to deliver welding power to a cladding strip that is driven between the first and second contacts, a first contact pressure adjuster to set a first pressure applied by the first and second contacts to the cladding strip, and a first strip lock preventer to limit the first pressure applied by the first and second contacts to the cladding strip to less than a threshold pressure.

Granular welding flux delivery devices and strip cladding systems with granular welding flux delivery devices are disclosed. A disclosed example granular welding flux delivery device includes a hopper having: an intake opening to receive granular welding flux; a chute; and an output opening to output the granular welding flux to an electroslag strip cladding process, a submerged arc welding process, or a submerged arc strip cladding process. The example granular welding flux delivery device further includes a chute divider positioned within the chute to reduce an intake rate of granular material through the intake opening by reducing a cross-section of the chute based on a dimension of the chute divider. The disclosed example granular welding flux delivery device includes an adjustable output cover attached to the chute proximate to the output opening to extend or retract a length of the chute by adjusting a location of the output opening along the chute.