Patent ID: 8207468

Claim:
A welding apparatus of a stainless steel pipe comprising: a welding torch jetting argon gas for shielding oxygen into a gap of the steel pipe rolled in a circular shape, while fusing at least one of a base metal and a welding material; and a gas supply pipe installed inside the steel pipe, the gas supply pipe having a jetting nozzle which jets argon gas at a rate of 4 to 20 l/min toward an inner surface of a welding bead portion formed at the gap of the steel pipe, where welding has been already completed and which is positioned backwardly at a predetermined distance from a welding bead portion where welding is being performed by the welding torch such that the argon gas jetted from the jetting nozzle cools and solidifies the welding bead portion where welding has been already completed and then, spreads towards the inner surface of the welding bead portion, where welding is being performed, for preventing the inner surface of the welding bead portion from being oxidized.