COOLING METHOD AND REPAIRING METHOD OF HOT AIR PIPE

PROBLEM TO BE SOLVED: To provide a cooling method and a repairing method of a hot air pipe which can introduce external air into a hot air main pipe and a hot air branch pipe existing on the hot air main pipe side rather than the hot air valve side in order to achieve shortening of a repair period by efficient cooling of the hot air pipe and which also can perform sufficient suction of the external air.SOLUTION: A hot air pipe 30 includes: a hot air main pipe 31 which reaches a blast furnace; a plurality of hot air branch pipes 32B and 32D which connect the hot air main pipe 31 to a hot blast stove 10, and hot air valves 33 which are placed in the middle of the hot air branch pipes 32B and 32D. A method for cooling the hot air pipe 30 includes: a preparation step of, to a repair part 9 in the hot air main pipe 31, removing the hot air valve of the hot air branch pipe 32C closest to the repair part 9 and also placing a supplementary bleeder 41 to the hot air branch pipes 32B and 32D adjacent to the closest hot air branch pipe 32C; and a cooling step of sucking the external air into the hot air branch pipe 32C closest to the repair part 9 from the place from where the hot air valve is removed and forming an external air flow F2 discharged from the supplementary bleeder 41 through the repair part 9.