To provide an apparatus for expanding pipe capable of affording a pipe excellent in roundness, and a method for manufacturing a steel pipe using it.
When a pipe is expanded by the apparatus for expanding pipe having an pipe expanding head 2 provided at the tip of the boom 3 and at least a pair of rollers 1a, 1b for constraining an expansion object pipe, i.e., a steel pipe equivalent to the X60 grade or higher of API Specification having a pipe diameter to wall thickness ratio of ≥60 to ≤200, from its inner face side to the diameter direction in the vicinity of the pipe expanding head, the roller having a width of ≥70 mm, a center thick shape having a curvature at the drum part of ≥85% to ≤105% of a nominal inner diameter of the object pipe and a roller mounting height of ≥49% to ≤51% of the nominal inner diameter of the object pipe is employed. The pipe expanding ratio is set to ≥0.6% to ≤1.2%.
MORI SHINICHIRO
HIDE HIROYUKI
KUBOTA YASUSHI
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