Abstract: A boiler having a furnace, a tunnel section and a rear gas duct is improved by the fact that a partition wall at right angles to side walls of the rear gas duct is disposed in the rear gas duct to divide it into two passages. A low-pressure reheater is disposed in the divided passage nearest to the tunnel section and has a narrow width. Two partition walls are disposed in the other divided passage parallel to the side walls of the rear gas duct to further divide the passage into three passages. Superheaters are disposed in the further divided passages close to the side walls and a high-pressure reheater is disposed in the central further divided passage. In another embodiment, the locations of the superheater and the high-pressure reheater are reversed.

Abstract: A butt welded tube is provided having excellent properties by the steps of forming a skelp onto a round shape, butt welding the edges thereof with butt welding rolls, blowing oxygen or air into the weld zone, so that said zone is brought to a melted condition with oxidizing heat based on said blowing and some notches which are formed are blown off with said blowing, and then said tube is passed through a train of reducing rolls to obtain a smooth surface and the required dimension of said tube.