PURPOSE: To prevent an U-shaped part of a heat-transmitting pipe from being vibrated or broken, by a method wherein vibration of a vortex in a multi-pipe cylinder U-pipe type heat exchanger and resonance of a heat-transmitting pipe are prevented by a final baffle, the heat-transmitting pipe is supported, and an end plate side pipe base is provided in front of the final baffle.

CONSTITUTION: The final baffle 4 is so provided that a fluid (a) entering the heat-transmitting pipe 1 from the side of a water chamber 3 and a fluid (b) entering from the side of a shell body 2 can deflectedly flow between baffles 5 appropriately arranged so as to prevent the pipe 1 from vibrating, and can flow out through the end plate side pipe base 7 while exchanging heat with each other. The final baffle 4 is made to support all of the heat-transmitting pipes 1 so that the U-shaped part the U-shaped part of the U-pipe does not vibrate and the fluid (b) is prevented from flowing into the U-shaped part in a large quantity. Further, the end plate side pipe base 7 is povided in front of the final baffle 4, whereby the fluid (b) is prevented from flowing into the U-shaped part in a large quantity, so that the frequency of vibration of the vortex generated due to the flow of the fluid (b) can be reduced. Accordingly, the heat-transmitting pipes 1 can be prevented from being damaged due to resonance.