| 摘要 |
PURPOSE:To preheat uniformly the entire part of a long-sized hollow structure and to reduce the strain owing to welding by ejecting hot wind from a perforated hot wind pipe inserted into the hollow part of said structure and installing an electrical heater on the outside surface thereof. CONSTITUTION:Two distribution pipes 9, 9 for hot wind are inserted into the hollow part of a structure, and many ejection holes 10 for hot wind are formed to the pipe 9. The hot wind forced into the pipe 9 from a hot wind generator 11 is ejected in the hollow part to preheat the inside surface of the structure from the inside surface. The ejecting direction of the hot wind is directed to a guide plate 2 and the thick-walled member of a rack 4 to preheat uniformly the thick- walled member having large heat capacity and the thin-walled member having small heat capacity. An electrical heater 12 is installed on the outside surface of the structure by each prescribed interval on the longitudinal direction on both top surface sides of the plate 2 and both side surfaces of the rack 4 to preheat the structure from the outside surface. |
