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.