WELDING METHOD

PURPOSE:To assure prescribed strength in welding parts by interposing sheetlike spacing members between the end faces of a backing material arranged on one prismatic body and the end faces of the other prismatic body and executing welding to the bevel formed on the one prismatic body. CONSTITUTION:The bevel 3 is formed in the part 2 to be welded of the prismatic body A1 and the bevel 3 is subjected to rust inhibitive coating. The end face 5 of the planar backing material 4 is pressed to the peripheral surface 2a on the rear side of the part 2 to be welded so as to project to the end face 6 side of the other prismatic body B1. The sheet-like spacing materials 7 are interposed between the end faces 5 at the four corners of the backing material 4 and the end faces 6 at the four corners of the other prismatic body B1, by which the end faces 5 of the backing material 4 and the end faces 6 of the prismatic body B1 are slightly parted from each other. The bevel 3 is subjected welding by an automatic welding machine. The welding is executed sequentially from the side where the prismatic bodies A1, B1 face each other.