METHOD OF MANUFACTURING MEDIUM DIAMETER SEAMLESS STEEL PIPE

PROBLEM TO BE SOLVED: To provide a method of manufacturing a medium diameter seamless pipe by which eccentric uneven thickness of the rolled stock succeeding to a detected rolled stock is reduced by detecting the generation of the eccentric uneven thickness on the spot during the piercer rolling of the same pipe-making lot. SOLUTION: In the method of manufacturing the medium diameter seamless steel pipe including the piercer rolling by which the inclined rotation piercing rolling is performed with upper and lower rolls 31, 32 and a plug 11 between the rolls while guiding the rolled stock 9 with right and left shoes 33, 34, by monitoring shoe load during the piercer rolling, the shoe position on the side where a monitored value is below the prescribed lowest limit is changed to a position near the pass center line. COPYRIGHT: (C)2008,JPO&INPIT