| 摘要 |
PROBLEM TO BE SOLVED: To prevent environmental pollution due to scattering of thermal insulation material while improving appearance by winding a thermal insulation material, e.g. glass wool or neoprene around various ducts, including a rectangular tubular duct, and racking the outside thereof with an exterior material, e.g. a steel plate. SOLUTION: A thermal insulation material 2a, e.g. glass wool, is wound, by a specified thickness, around a rectangular tubular duct 1a a circular tubular duct and a spiral duct formed with various size and length in a factory and the outside thereof is wrapped and racked with a thin exterior material 3, e.g. a galvanized sheet, a tinplate, a stainless plate or a vinyl chloride steel plate. Racking is performed by fitting the single seam 3b of an exterior material 3 provided with double seams 3a at the opposite ends thereof over the entire length and an exterior material 3 provided with single seams 3b at the opposite ends thereof over the entire length from the inlet of the double seams 3a and hooking an intermediate button punch repulsively to a hook. |
