| 摘要 |
<p>PURPOSE:To prevent generation of corrosion and crack during storing and after welding in the end parts of double pipe by forming a build-up weld zone by annular corrosion resistant metal on the inner side in the end parts of the double pipe consisting of a non-corrosion resistant outside pipe and a corrosion resistant inside pipe and working said parts to form a joint. CONSTITUTION:In the end parts of corrosion resistant double pipe 3 consisting of an outside pipe 1 made of carbon steel and an inside pipe 2 consisting of stainless steel, the length of the pipe 2 is made shorter than the length of the pipe 1 to provide a level difference part 10 between both. While the end part of the pipe 1 is pulled axially with a suitable means, stainless steel is build-up welded 11 to an annular shape in the part 10 to bind the end part 2' of the pipe 2 and the inside surface at the end of the pipe 1 metallurgically to one body. The tensile force upon the pipe 1 is relieved to form a residual compressive stress that prevents stress corrosion cracking in the end parts of the pipes. Thereafter, the build-up weld zone 11 is worked 8 with a joint by machining or the like. The initiation of corrosion from the boundaries between the outside and inside pipes during storage and the generation of cracking in the weld zones after the welding are prevented.</p> |
