| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for producing a UOE steel pipe, upon production of a UOE steel pipe having a tensile strength of ≤705 MPa, capable of achieving the improvement of efficiency and the reduction of welding defects in tack welding.SOLUTION: Upon U forming, the U forming is performed under the condition where the ratio between the width (W) of a U pipe and the outer diameter (D) of a UOE steel pipe, (W/D) reaches 0.60 to 0.75, and upon tack welding, the tack welding is performed while applying a pressing amount of 0.5 to 1.0% of the outer diameter of an O pipe 1 in which a seam part 1a is located in the upper side to the O pipe 1 from the right and the left sides by a right side cage roll 6c and a left side cage roll 6g, and further, while applying a pressing amount of 0.1 to 0.5% of the outer diameter of the O pipe 1 from the upper part by an upper side cage roll 6a. |
