| 摘要 |
PROBLEM TO BE SOLVED: To provide a device for shielding a pipe stock welded part of an electric resistance welded steel pipe, to provide a method of shielding a pipe stock welded part, and to provide an electric resistance welded steel pipe manufacturing method using the shielding method, which can sufficiently reduces an oxygen concentration in the welded part to prevent forming of penetration by surely shielding the welded part with gas during electric resistance welding without sacrificing the aspect of pipe manufacturing cost and the aspect of efficiency.SOLUTION: Shield gas is blown to a welded part from a gas discharge port of a shield gas blowing nozzle 1 in which a gas discharge port 1A is divided into three layers with respect to a pipe stock circumferential direction and is arranged at a position 5 to 300 mm above an upper end of the welded part. A gas discharge flow rate B from the central layer among the three layers of the discharge port is set as B=0.5 to 50 m/s, and a gas discharge flow rate A from both the remaining end layers of the gas discharge port is set to satisfy 0.01≤B/A≤10. |
