HEAT TREATMENT OF HEAT TRANSFER PIPE OF HEAT EXCHANGER FOR NUCLEAR REACTOR

PURPOSE:To improve the corrosion resistance at the specific point of a heat transfer pipe by removing water from the inside of a heat exchanger, inserting a heater into the heat transfer pipe and heating the desired position of the pipe in the range where the relation between time and temp. is specified. CONSTITUTION:The water in the heat exchanger for a nuclear reactor is removed and the heater is inserted into the heat transfer pipe until the heater arrives at the desired position, then this section is heated. The heating conditions are determined within the polygon peaking at the points; A (1,000min, 750 deg.C), B (260min, 750 deg.C), C (260min, 680 deg.C), and D (1,000 deg.C, 640 deg.C) in the graph indicating the heat treating conditions with time and temp. at this time. The damages to be caused by the intergranular corrosion and residual stress in the desired section are thereby effectively prevented. Stress corrosion cracking is effectively prevented if the respective heat conditions are so determined as to be within the polygon peaking at the points; (a) (8min, 820 deg.C), (b) (0.5min, 890 deg.C), (c) (0.5min, 800 deg.C), (d) (0.9min, 720 deg.C), (e) (18min, 640 deg.C), and (f) (8min, 720 deg.C).