To develop a technique which prevents molten steel from picking up nitrogen by infiltration of the nitrogen in the atmosphere air from the outside of an immersion pipe of a degassing treatment device when melting extra-low nitrogen steel.
Gas piping 21 is disposed within the thick part of at least the descending side immersion pipe 3 and at a portion of this piping is provided with a gas outlet 21 and is so provided therewith in such a manner that the outlet is not exposed to the outer peripheral surface and inner peripheral surface of the piping 21. Inert gas is filled in the refractory 4 segment within the thick part of the immersion pipe to shut off the infiltration of the nitrogen in the atmosphere air into the immersion pipe. A plurality of the he supply piping 21 for the inert gas for preventing the infiltration of the atmosphere air into the immersion pipe 3 are previously branched from a header pipe 24 and are disposed to improve execution workability and to prevent the leakage of the inert gas.
SAKURAI EIJI
KOMATANI MASANORI
NIMURA YOICHI
TANABE HARUYOSHI
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