Patent ID: 9468967
Filing Date: 2016-10-18
CPC Classification: B21D,C10M,C10N,C22C

Claim Text:
1. A pipe end correction method of a seamless pipe for correcting an inner diameter of pipe end of a seamless pipe made of a high Cr stainless steel containing 8 to 35 mass % Cr, and 0.1 to 10 mass % Ni, the pipe end correction method comprising: a hot tube-making step; a heat treatment step; a lubricant film forming step, following the tube-making step and the heat treatment step, of applying lubricant at least either on an inner surface of a pipe end portion of the seamless pipe or on a surface of a plug for inner diameter correction while oxide scale remains accumulated on the inner surface of the pipe end portion of the seamless pipe; a pipe end correction step, following the lubricant film forming step, of forcing the plug into an inside of the pipe end portion of the seamless pipe so as to expand the pipe end portion; a shotblasting step, following the pipe end correction step, of applying shotblasting to the seamless pipe; and: an acid pickling treatment step, the shot blasting step, of acid pickling the seamless pipe.