IMPROVEMENT OF RESIDUAL STRESS OF DOUBLE METALLIC PIPE OR THE LIKE

摘要

PURPOSE:To form a residual compressive stress in double pipes consisting of a base pipe made of an austenitic stainless steel and thermal sleeve therein and to prevent the corrosion cracking by a residual tensile stress by heating the base pipe of said double pipes from the outside while passing cooling water between the two pipes. CONSTITUTION:The double pipes for a pressure vessel 1 of a nuclear reactor are formed by providing a thermal sleeve 5 to the inside of the base pipe 4 which is made of the austenitic stainless steel and includes a nozzle 2 and a safe end 3. The cooling water from a cooling water nozzle 7 is filled in the base pipe 4 and the thermal sleeve 5 and while the cooling water is spouted into a hollow cylindrical part 6 formed of the two pipes, the base pipe 4 is heated by a heating means 8 on the outside. A temp. difference arises in the thickness direction of the base pipe 4 and the residual compressive stress is generated to the inside surface near a welded joint 9 of the double pipes, by which the generation of the corrosion crack based on the residual tensile stress is prevented.