Welding wire preheating systems and methods are disclosed. An example welding method includes: receiving a signal indicative of initiation of welding process; prior to initiating a welding arc based on the received signal, controlling voltage or current applied to a welding electrode to preheat the electrode to a temperature above an ambient temperature but below a melting point of the welding electrode; monitoring feedback voltage to determine a termination of preheating; and terminating preheating prior to initiating the welding arc in accordance with a welding protocol.

Welding wire preheating systems and methods are disclosed. An example welding method includes: receiving a signal indicative of initiation of welding process; prior to initiating a welding arc based on the received signal, controlling voltage or current applied to a welding electrode to preheat the electrode to a temperature above an ambient temperature but below a melting point of the welding electrode; monitoring feedback voltage to determine a termination of preheating; and terminating preheating prior to initiating the welding arc in accordance with a welding protocol.

According to an aspect of the present invention, there is provided a flux-cored wire including a steel sheath and a flux that fills the steel sheath. The flux contains fluorides of which a total value a of F-equivalent values is 0.21% or more, oxides of which the total value of amounts ranges from 0.30% to less than 3.50%, and carbonates of which a total value of amounts ranges from 0% to 3.50%. An amount of CaO ranges from 0% to less than 0.20%. An amount of iron powder ranges from 0% to less than 10.0%. A X-value is 5.0% or less. The amount of CaF.sub.2 is less than 0.50%. The amount of Ti oxides ranges from 0.10% to less than 2.50%. A ratio of to ranges from 0.10 to 4.00. A total value of amounts of MgCO.sub.3, Na.sub.2CO.sub.3, and LiCO.sub.3 ranges from 0% to 3.00%. Other chemical composition is within a predetermined range. Ceq ranges from 0.45% to 1.20%.

According to an aspect of the present invention, there is provided a flux-cored wire including a steel sheath and a flux that fills the steel sheath. The flux contains fluorides of which a total value a of F-equivalent values is 0.21% or more, oxides of which the total value of amounts ranges from 0.30% to less than 3.50%, and carbonates of which a total value of amounts ranges from 0% to 3.50%. An amount of CaO ranges from 0% to less than 0.20%. An amount of iron powder ranges from 0% to less than 10.0%. A X-value is 5.0% or less. The amount of CaF.sub.2 is less than 0.50%. The amount of Ti oxides ranges from 0.10% to less than 2.50%. A ratio of to ranges from 0.10 to 4.00. A total value of amounts of MgCO.sub.3, Na.sub.2CO.sub.3, and LiCO.sub.3 ranges from 0% to 3.00%. Other chemical composition is within a predetermined range. Ceq ranges from 0.45% to 1.20%.

Methods for welding a particle-matrix composite body to another body and repairing particle-matrix composite bodies are disclosed. Additionally, earth-boring tools having a joint that includes an overlapping root portion and a weld groove having a face portion with a first bevel portion and a second bevel portion are disclosed. In some embodiments, a particle-matrix bit body of an earth-boring tool may be repaired by removing a damaged portion, heating the particle-matrix composite bit body, and forming a built-up metallic structure thereon. In other embodiments, a particle-matrix composite body may be welded to a metallic body by forming a joint, heating the particle-matrix composite body, melting a metallic filler material forming a weld bead and cooling the welded particle-matrix composite body, metallic filler material and metallic body at a controlled rate.

Methods for welding a particle-matrix composite body to another body and repairing particle-matrix composite bodies are disclosed. Additionally, earth-boring tools having a joint that includes an overlapping root portion and a weld groove having a face portion with a first bevel portion and a second bevel portion are disclosed. In some embodiments, a particle-matrix bit body of an earth-boring tool may be repaired by removing a damaged portion, heating the particle-matrix composite bit body, and forming a built-up metallic structure thereon. In other embodiments, a particle-matrix composite body may be welded to a metallic body by forming a joint, heating the particle-matrix composite body, melting a metallic filler material forming a weld bead and cooling the welded particle-matrix composite body, metallic filler material and metallic body at a controlled rate.

A method for manufacturing boiler tubes includes the steps of removing end caps from a plurality of tubes, the plurality of tubes including at least a first tube and a second tube, cleaning an outer surface of the first tube and the second tube, forming a weld preparation on an upstream end of the first tube, forming a weld preparation on a downstream end of the second tube, welding the upstream end of the first tube to the downstream end of the second tube to form a butt weld, to produce a long tube, and with an automated device, measuring a parameter of at least the first tube and the second tube. The steps of removing the end caps, cleaning the outer surface of the tubes, forming the weld preparations, welding the first tube to the second tube, and measuring the parameter are performed autonomously.

The present disclosure is directed to a system and method for preventing damage to one or more components of the gas turbine engine during a repair procedure. The method includes locating one or more gaps of one or more components of the gas turbine engine in the vicinity of the defect. Further, the method includes filling the one or more gaps with a filler material so as to prevent arcing over the gaps during repair. Thus, the method also includes applying an electrical discharge to the defect.

The present disclosure is directed to a system and method for preventing damage to one or more components of the gas turbine engine during a repair procedure. The method includes locating one or more gaps of one or more components of the gas turbine engine in the vicinity of the defect. Further, the method includes filling the one or more gaps with a filler material so as to prevent arcing over the gaps during repair. Thus, the method also includes applying an electrical discharge to the defect.

The present invention relates to an air conditioner. The air conditioner according to the present embodiment has a refrigeration capacity of 11 kW to 16 kW, inclusive, and uses R32 as a refrigerant circulating therein, and since a refrigerant pipe therein is made of a ductile stainless steel material having 1% or less of a delta-ferrite matrix structure with respect to the grain size area thereof, the refrigerant pipe can maintain strength and hardness as good as or better than those of a copper pipe, while also maintaining good processability.