| 摘要 |
PURPOSE:To manufacture the titled pipe having superior fire resistance and causing a small fusion loss by dipping an iron pipe in molten Al to form an Al permeated layer and an Al stuck layer on the pipe, subjecting the pipe to oxidation calcining treatment, and coating the pipe surface with a heat insulator. CONSTITUTION:Al or an Al alloy is melted by heating and kept at 650-1,000 deg.C. An iron metallic body such as a steel pipe is dipped in the molten Al to form an Al permeated layer on the pipe surface and a stuck Al layer on the permeated layer after a fixed time. This pipe is subjected to oxidation calcining treatment to oxidize the outermost stuck Al layer, forming an aluminum oxide layer. The surface of the treated pipe is then coated with a heat insulator to manufacture a gas blowing pipe. As the insulator an inorg. oxide or a mixture of the oxide and a nonoxide having >=1,400 deg.C m.p. is preferably used. |
