To provide a structure for joining tubes made of different metals which are highly reliable and are excellent in strength and airtightness.
The tubes 1 and 2 made of different metals respectively are joined by means of a joining fixture 3 composed of two-layer clad metal plates. The two different metals composing the two-layer clad plates are of the same materials as the tubes 1 and 2 of the different metals respectively. The joining fixture 3 is formed like a flange having a cylindrical rising portion 4 with open ends, by burring the two-layer clad metal plates after boring prepared holes in the two-layer clad metal plates beforehand. Then the tubes 1 and 2 of the different metals respectively are fitted into the outer circumferential face side 4a and inner circumferential face side 4b of the rising portion 4 respectively so that the metals of the same kind touch each other. Only the portions where the metals of the same kind touch each other are joined by welding or brazing.
ISHIDA HIDEO
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