PURPOSE: To safely and efficiently cool the upper part of a converter by allowing cooling water to flow in an inside pipe of a double pipe fitted to outer surface of a contracted part iron shell at the time of cooling the contracted part at the upper part of the converter.

CONSTITUTION: The upper contracted part 6 of the converter 1 becomes extremely high temp. and in order to prevent shortening of the service life of converter due to erosion of lining refractory brick 3, thermal deformation of an iron shell 5 at this part and breakage of the contracted part 6, the double cooling pipe 2 composed of the inside pipe 7 and outside pipe 8 on the surface of the iron shell 5 at the upper contracted part 6 in the converter 1, is welded 10 to allow the cooling water to flow in the inner part 9 of the inside pipe 7. The contracted part 6 becoming high temp. at the upper part of the converter is effectively cooled and the thermal deformation of the iron shell 5 and the erosion of the lining refractory brick 3 at this part can be prevented. Further, as the cooling water pipe is made of the double pipe structure, water leakage due to crack in the outside pipe 8 and the iron shell 5 as centering the weld part 10 is prevented, and the safe operation can be executed for long time.