BUTTED GAS SHIELDED ARC WELD JOINT, AND BUTTED GAS SHIELDED ARC WELDING METHOD

摘要

PROBLEM TO BE SOLVED: To provide a welding method and a welding apparatus for preventing any high-temperature cracking from occurring even when the welding is executed at the welding rate of ≥1.5 m/min which is equal to or higher than the present state irrespective of the grade (material) of a steel tube, forming a smooth weld bead in an overhead attitude, and obtaining a stable welding quality in the root pass welding of the butted gas shielded arc welding of steel tube ends to each other, which is applied to site installation work of a submarine pipeline.;SOLUTION: In the root pass welding of the butted gas shielded arc welding of steel tubes to each other, a U-shaped groove shape is formed, in which the groove angle of a groove portion of a butted part is made ≥3° and ≤5°, the root face is made ≥1.0 mm and ≤1.5 mm, and the width of the groove root part is made ≥3.5 mm and ≤4.7 mm. The penetration bead width after the welding is ≥4.5 mm, and the ratio of the height of a dendrite structure from the penetration bead side to the total height of the weld bead in the sectional shape of the weld bead is ≥0.5.;COPYRIGHT: (C)2011,JPO&INPIT