METHOD OF CONTINUOUS PIPE ROLLING Russian patent published in 2016 - IPC B21B17/00 

FIELD: process engineering.

SUBSTANCE: invention relates to production of seamless hot-rolled pipes by rolling at multistand long-mandrel mills. Billet is rolled at multistand long-mandrel mill with sequential reshaping of its profile to regular polyhedron, oval and round shape and, finally, to regular polyhedron. Note here that billet rolling is performed at long floating mandrel simultaneously at several series stands with polyhedral symmetric gages arranged mutually perpendicular at 45 degrees to horizon. At rolling, said billet is shaped to regular polyhedron with the number of faces not smaller than 10.

EFFECT: higher precision of wall depth, elimination of flaws at OD.