| 摘要 |
PURPOSE:To make it possible to control the buckling of heat transfer pipes by a method wherein the inlet side heat transfer pipe is welded to a pipe plate after it is expanded in the axial direction so that a tensile residual stress is given to the pipe in advance. CONSTITUTION:The heat transfer pipes 1 of the multiple type heat exchanger and the pipe plates 2 and 2A are assembled together such that all of the heat transfer pipes are welded to the pipe plate 2 and then to the lower pipe plate 2A with the exception of the pipe 1A which is heated to a higher temperature than the remaining pipes at the time of operation of the heat exchanger. After that, an electrical heater 11 and a thermocouple 12 are inserted into the pipe 1A so that the amount of expansion of the pipe 1A is adjusted by the heating temperature controlled through a temperature adjuster 13 and by the position of the heater 11 and when a predetermined thermal expansion is obtained on the pipe, the lower end 14 of the pipe 1A is welded to the pipe plate 2A. In this case, the heating of the pipe 1A is terminated after the welded section is cooled. Thus the heat transfer pipe 1A is given a tensile residual stress and even when the pipe 1A is expanded greatly because of its being located opposite a high temperature primary fluid inlet 7, its thermal deformaton is absorbed by the tensile residual stress. |
