| 摘要 |
PURPOSE:To perform a new welding without the need for back sealing by abutting the mutual bevelings formed on the edge end of a pipe and by welding respectively the initial layer zone and double layer zone with the same material as the following welding material after performing the build-up welding of the groove for build-up provided on the inner surface of the pipe with the welding material of low alloy steel. CONSTITUTION:The groove 2 for build-up which extends from the edge end of the inner surface of a pipe 1 to the inner side is provided thereon (Fig. a), then a build-up part 3 is formed by performing a build-up welding with the welding material of low alloy steel (Fig. b). A beveling 4 is then provided by performing the beveling for piping welding after the build-up welding (Fig. c). Then, the beveling mating of the pipe 1 with another pipe 5 is performed as shown in Fig. d and the welding is performed on the initial layer zone 6 with inert gas arc welding by using the same material as said welding material, and on the 2nd layer and on, namely a double layer zone 7 by using the same welding material as that of pipe material (Fig. e). In this piping welding no back shielding is necessary by an Ar gas, etc.
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