Patent ID: 6073331
Filing Date: 2000-06-13
Classification: B21B,Y10T

Abstract:
A method for manufacturing a seamless pipe, comprising the steps of:preparing a billet made of an alloy steel or an alloy having a main component selected from the group consisting of Cr, Ni and Mo;joining a steel plate at least to an end surface of the billet at which a piercing of the billet is to be commenced;preparing a piercing plug made of Mo, a Mo alloy or a heat resistant steel;hot-piercing the billet at a hot-piercing temperature, to which the steel plate is joined, with the piercing plug by a Mannesmann piercing to produce a hollow shell;an oxide scale being formed from said steel plate, at the hot-piercing temperature, the oxide scale lubricates the piercing plug during the hot-piercing;rolling the hollow shell to produce a seamless pipe.