A welding or additive manufacturing system includes a contact tip assembly having first and second exit orifices. A wire feeder is configured to deliver a first and second wire electrodes through the exit orifices. An arc generation power supply is configured to output a current waveform to the wire electrodes simultaneously, through the contact tip assembly. The current waveform includes a bridging current portion, and a background current portion having a lower current level than the bridging current portion. The bridging current portion has a current level sufficient to form a bridge droplet between the wire electrodes before the bridge droplet is transferred to a molten puddle during a deposition operation. Solid portions of the wire electrodes do not contact each other during the deposition operation. The bridge droplet is transferred to the molten puddle during a short circuit event between the molten puddle and the wire electrodes.

Embodiments of welding machines and methods for switching between electrically isolated welding output studs. One embodiment of a welding machine includes multiple welding output studs, a work stud, a contactor circuit, touch sense circuitry, and a contactor controller. The contactor controller is configured to determine that electrical contact has occurred between a first welding output stud of the multiple welding output studs and the work stud via the touch sense circuitry. The contactor controller is also configured to deactivate welding output power to other welding output studs of the multiple welding output studs via the contactor circuit based on determining that the electrical contact has occurred. The contactor controller is further configured to activate welding output power to the first welding output stud via the contactor circuit after deactivating the other welding output studs based on determining that the electrical contact has occurred.

A system and method of welding or additive manufacturing is provided where at least two welding electrodes are provided to and passed through a two separate orifices on a single contact tip and a welding waveform is provided to the electrodes through the contact tip to weld simultaneously with both electrodes, where a bridge droplet is formed between the electrodes and then transferred to the puddle.

A system and method of welding or additive manufacturing is provided where at least two welding electrodes are provided to and passed through a two separate orifices on a single contact tip and a welding waveform is provided to the electrodes through the contact tip to weld simultaneously with both electrodes, where a bridge droplet is formed between the electrodes and then transferred to the puddle.

Apparatuses and methods for repairing a defect in a nuclear reactor are provided. The apparatus includes a body for insertion in a tubular structure, the body includes: an end effector having a weld torch operable to deposit weld material by forming molten weld droplets and depositing the weld droplets the tubular structure. A drive unit includes a brace for selectively anchoring against said tubular structure; at least one linear actuator for moving the apparatus relative to the brace; and a rotational actuator coupled to rotate the weld torch. The method includes inserting a repair apparatus into tubular structure of the nuclear reactor; moving the repair apparatus to a defect location; depositing a protective weld layer over the defect by sequentially depositing weld droplets atop a weld pool on the tubular structure, wherein the protective weld layer bonds to the tubular structure surrounding the defect.

A system and method of welding or additive manufacturing is provided where at least two welding electrodes are provided to and passed through a two separate orifices on a single contact tip and a welding waveform is provided to the electrodes through the contact tip to weld simultaneously with both electrodes, where a bridge droplet is formed between the electrodes and then transferred to the puddle.

The amount of manganese in the weld fumes generated by an arc welding process can be reduced without reducing the concentration of manganese in the weld deposit ultimately obtained by supplying the manganese to the weld site by the hot wire welding electrode of a hot wire welding process.

A plurality of welding torches, which are disposed in a welding device and are made movable in three-dimensional directions, are provided with welding wires that differ in composition and diameter from each other. When welding is performed in the horizontal direction, an arc is generated by at least two of the welding torches to form a bead while the welding wires are being fed. When welding is performed in the vertical direction, the arc is generated by any one welding torch of the two welding torches to form a bead while the welding wire is being fed. Thus, a steel sheet to which an anti-corrosion material has been applied can be welded continuously with high quality and high-efficiency in a horizontal orientation and vertical orientation.

A method and device for gas metal arc welding, wherein a current-carrying wire electrode is melted by an arc, and wherein gas metal arc welding is performed using a filler metal, which contains at least one constituent that releases deleterious emissions through evaporation, wherein a composition that does not contain this constituent is selected for the wire electrode, and a dead weld metal containing this constituent is fed to the arc and/or a molten bath without a current.

A twin wire welding apparatus including a first contact tube for guiding a first consumable electrode toward a weld puddle and transferring welding current to the first consumable electrode, a second contact tube for guiding a second consumable electrode toward said weld puddle and transferring welding current to the second consumable electrode, and a single power source connected to said first and second contact tubes for providing the same potential to said two consumable electrodes, and a method for operating such an apparatus.