| 摘要 |
Down weldable steel pipes and their welding joint method are provided in which a weld even in the lower portion can be performed in a downward position inside the pipes by cutting an inside edge in the lower portion of the pipes so that a weld in the lower portion can be performed approximately in a downward position, but not in an upward position. An inner cutting surface (4) is formed at the lower portion of each end of the large-diameter steel pipes (1, 2), and an outer cutting surface (3) is formed at the upper portion thereof. Welding is performed approximately in the downward or horizontal position inside and outside the pipes after prewelding one side of a backing bar (11) at the lower outer surface of the previously installed large-diameter steel pipe (2) and placing the large-diameter steel pipe (1) to be installed on other side of the backing bar (11). |
