Welding method using special torch

A welding method, comprising:

• performing welding by feeding a flux cored wire to protrude from a contact tip and produce a protruded portion, while discharging an electric current through the protruded portion of the flux cored wire, to form an electric arc and melt the protruded portion of the flux cored wire;
• supplying a shielding gas from a shielding gas nozzle, to provide a gas shield around the protruded portion of the flux cored wire;
• and
• sucking the shielding gas during the welding step using a suction nozzle provided between the contact tip and the shielding gas nozzle,
• wherein the flux cored wire comprises:
• a steel outer casing,
• a flux filled inside the steel outer casing, and
• a seam portion of the steel outer casing where opposing ends of the steel outer casing in a width direction of the steel outer casing are butted or overlapped, the seam portion extending in a longitudinal direction of the flux cored wire,
• wherein, in a cross section of the seam portion, when a length of a portion of a clearance between said ends of the steel outer casing where the size of the clearance is less than 20 μm is denoted by La, a length of a portion of said clearance where the size of the clearance is 20 μm or more and less than 40 μm is denoted by Lb, and a length of a portion of said clearance where the size of the clearance is 40 μm or more and less than 100 μm is denoted by Lc, a value represented by Lseam=2.0×La+1.5×Lb+Lc is 0.1 to 1.5 mm.