PURPOSE: To improve the safety and reliability of piping equipment by mounting piping for gaseous oxygen and hydrocarbon within a trunnion shaft and trunnion block for tilting the body of a top blown converter in adding a bottom blowing device to said converter.

CONSTITUTION: Double tuyeres of a tuyere for bottom blowing of oxygen and an outer side pipe for blowing of gaseous hydrcarbon for cooling such as propane for the purpose of protecting the refractory material for tuyeres are provided in the bottom part of an oxygen top blown converter. In the new installation of pipings for supplying of gaseous oxygen for blowing and gaseous hyrocarbon for cooling, the furnace body shell 1 and lining refractory bricks opposite to the shaft hole 3b opened in the end part on the inner side of a trunnion shaft 3 for tilting of the body are notched, and operations such as expanding, working and cutting of the gas flow passage hole in the shaft 3 as well as connecting of pipes and pipe joints are carried out by utilizing the hole made in this way, and upon completion of the operations, the notched parts of the shell and the refractory bricks are restored, whereby the pipings for gaseous oxygen and hydrocarbon are mounted safely by utilizing the trunnion shaft and the block.