METHOD FOR HEAT-TREATING METAL TUBES OR PIPES FOR NUCLEAR POWER PLANT, BATCH-TYPE VACUUM HEAT TREATMENT FURNACE USED THEREFOR, AND METAL TUBES OR PIPES FOR NUCLEAR POWER PLANT HEAT-TREATED BY THE SAME

摘要

Disclosed is a method of heat-treating metal pipes that are to be used in a nuclear power plant, the method involving: placing the metal pipes, which are to be placed in a batch-type vacuum heat-treatment furnace, on a plurality of metal beams that are lined up in the length direction of the metal pipes; and heat-treating said metal pipes; wherein the metal pipes are placed on the metal beams with a heat-resistant cloth having a thickness of 0.1 to 1.2 mm being disposed therebetween. Thus, it is possible to inhibit scratches from being formed on the outer surfaces of the metal pipes due to the heat treatment, and to reduce the staining of the outer surfaces of the metal pipes. Preferably, the composition, in percentage by mass, of each metal pipe used herein consists of: at most 0.15% of C; at most 1.00% of Si; at most 2.0% of Mn; at most 0.030% of P; at most 0.030% of S; 10.0-40.0% of Cr; 8.0-80.0% of Ni; at most 0.5% of Ti; at most 0.6% of Cu; at most 0.5% of Al; at most 0.20% of N; and Fe and impurities as the remainder.