IMMERSION TUBE FOR TREATING MOLTEN METAL AND MANUFACTURING METHOD THEREOF, AND VACUUM-DEGASSING METHOD

PROBLEM TO BE SOLVED: To provide an immersion tube and manufacturing method thereof, and a vacuum-degassing method with which regarding to the immersion tube for treating molten metal fitted to a vacuum vessel in the degassing vessel for degassing apparatus performing the degassing treatment in molten metal, the durability thereof is improved and the service life can drastically be prolonged. SOLUTION: The immersion tube for treating molten metal and the manufacturing method thereof, are performed as the followings, that is, a core metal 8 of the immersion tube 5, is a double tube-shape of an inside cylindrical iron plate 8a and an outside cylindrical iron plate 8b and on the inner and the outer circumferences and the bottom part, to the bottom part, to refractory brick 9 or a monolithic refractory 10 is disposed, and in a gap part 11 between the outside cylindrical iron plate 8b and the inside cylindrical iron plate 8a, the monolithic refractory 13 for filling up is filled up, and the monolithic refractory 13 for filling up is filled up and the monolithic refractory 13 for filling up, is ≤30% apparent porosity and ≥5MPa bending strength and a gas introducing tube 14 for flowing cooling gas into the gap part 11 of the core metal 8 is peculiarly disposed . Then, the monolithic refractory 13 for filling up, the refractory as the raw material of that having ≤2mm the maximum grain diameter is used. COPYRIGHT: (C)2008,JPO&INPIT