PURPOSE: To efficiently feed a short and hot metallic bloom at little fluctuating temperatures, to save the energy consumption, and to shorten the length of process, by arranging plural parallel heating furnaces following to the metallic bloom cutter.

CONSTITUTION: A long size square bloom is charged into the bloom heating furnace 1 and is extracted after heating; thus prepared hot bloom is processed by one or more of breakdown mills 2; hereby, the sectional area of the bloom is reduced and a long size bloom with a round section is obtained. This round bloom is cut by the cutter 3 into a length of the blank material to be fed to the piercing process; thus divided bloom is passed through either one of parallelly arranged plural heating furnaces 5-1, 5-2... or through the by-pass table 4, and is fed to the piercer 6. Then the divided bloom is pierced by the piercer 6 into a specified size and is sent to the continuous rolling mill 7. A mandrel is inserted into the pipe on the feed-in side of the mill 7; thereafter the pipe is continuously rolled by plural rolling stands in order to reduce the outer diameter and wall thickness of the pipe; the mandrel is withdrawn from the pipe on the run-out side of the mill 7. Thus obtained pipe is again sent to the reheating furnace 8 for the purpose of soaking it, and is subjected to the finishing pass carried out by the stretch reducer 9; after which, the pipe is sent to the next process.