| 摘要 |
PROBLEM TO BE SOLVED: To provide a porous plug capable of keeping a gas blowing operation under a good condition for a long period of time while reducing gas leakage. SOLUTION: This porous plug is characterized in that a plurality of iron rings 8 are fitted to the upper and middle portions of outer peripheral surface of a plug body 1 which is formed by covering the outer periphery of a porous refractory material 2 with a dense refractory material 5, and the lower and bottom portions of the outer peripheral surface is covered with a shell 6 having a gas conduit 7.
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