PURPOSE: To improve the purity of the gaseous atmosphere in a weld zone and to prevent consumption and welding defect of an electrode in the stage of subjecting a pipe and a pipe plate to TIG welding from the inside of the pipe by ejecting a shielding gas in the direction where the gas collides against the weld zone.
CONSTITUTION: A welding torch 10 is rotated by a welding device for inside surface of a pipe and a shielding gas is passed via a gas supply path 11 of a torch 10 through a gas flow regulating chamber 12. The shielding gas subjected to the flow regulation is passes approximately uniformly through the inside of a filter 15 and is ejected in the direction where the gas collides against a weld zone 8 via the hole parts of a guide 16 consisting of a perforated plate and a nozzle 16A. Since the atmosphere in the weld zone 8 is hardly evacuatable in this state, the amt. of the air leaking from the space between the guide 6 and the torch 10 decreases. A ring 17 for regulating the flow of the gas is formed at the top end part of the torch 10 and therefore the purity of the gaseous atmosphere near the weld zone 8 is further improved.
KOZONO YUUZOU
OGURA SATOSHI
TAKAHASHI YOUICHI
