WELDED-JOINT STRUCTURE IN THICK-WALLED LARGE-DIAMETER PIPE, AND WELDING METHOD THEREFOR

摘要

A pair of thick-walled large-diameter base pipes (1) constituted of an Ni-based alloy which comprises, in terms of wt%, 20-35% Cr, 0.1-10% Mo, 0.1-3% Al, 0.11-3% Ti, and Ni as the remainder and intermediate pieces constituted of the same material and having a width of about 60 mm are subjected beforehand to hot working or cold working, thereby giving a solution treatment to a range including portions to be finally welded on a site where at least a boiler has been installed. Thereafter, the intermediate pieces are finally welded to each other on the site where a boiler has been installed. With this method, it is possible to obtain a highly reliable welded-joint structure in a thick-walled large-diameter pipe.