| 摘要 |
PROBLEM TO BE SOLVED: To lessen the maximum outside diameter of a socket portion of a fireproof two-layered tube. SOLUTION: The fireproof two-layered tube 10 comprises an inner tube 11 forming a socket 13 in which a pipe is inserted to its end, and a fireproof outer tube covering the periphery of the inner tube 11. The outer tube comprises a first outer tube 30 covering at least the maximum outside diameter portion 13x of the socket 13, and second outer tubes 42 and 44 capable of covering a portion excluding the portion covered by the first outer tube 30. The first outer tube 30 is made of cast iron, and the second outer tubes 42 and 44 are formed by mixtures of cement with a nonflammable material. Thus, the maximum outside diameter of the socket portion of the fireproof two-layered tube is lessened when compared with the case in which the inner tube is covered by the outer tubes made of the mixture of the cement and the fireproof material in its entirety as it was. COPYRIGHT: (C)2004,JPO
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