| 摘要 |
PROBLEM TO BE SOLVED: To zero out penetrator crack and to cope with pipe dimension variation by performing gas shield welding in a seal box.SOLUTION: A welding method for an electroseamed steel pipe using a seal box includes, from an inlet side to an outlet side of a seal box (5), a seal box entrance gas supply pipe (30), a high frequency heating coil (22), a squeeze roll (23), a welding point gas supply pipe (31), a gas supply pipe (32) for adjusting seal box atmosphere, and an enzyme concentration meter (33). An impeder (8) is provided in an electroseamed steel pipe (6). The impeder (8)and an inner surface bead cutting device (7) are cooled with inactive gas of liquid at flow rate of 5 L/min or higher. The oxygen concentration in the seal box (5) is set to be 100 ppm or less, and a seal box atmosphere adjustment gas flow rate to be 100 L/min or higher. Gas flow rate from the welding point gas supply pipe (31) is set to be 50 L/min or higher. |
