Nkk Corporation

Yuji Sugitani

Masatomo Murayama

A method for one-side root path welding of a pipe joint comprises the steps of forming a ring groove having a V-shaped bottom portion thereof at end faces of both pipes whose joint is circumferentially welded, attaching a backing material to a butt portion of the pipes from an internal side of the pipes, running an automatic welding machine along a guide rail mounted on an outer surface of the pipes in the circumferential direction thereof, controlling a position of a welding torch along a seam by means of an arc sensor, and welding root pass from the outer side of the pipes with a predetermined welding current and at a welding speed in a high-speed rotating arc welding of the pipes at a predetermined rotational speed and with a predetermined diameter of rotation. The rotational speed of arc is from 10 to 150 Hz. The rotation diameter of the arc is from 1 to 4 mm. The welding current is from 200 to 500 A. The welding speed is from 75 to 300 cm/min.

Growing community of inventors

Kawasaki, Japan

Masatomo Murayama