Safety in Tube Bundle Heat Exchangers: Some Remarks on the Latest German Standard Concerning Flow-Induced Vibration

In 1997 a new German standard dealing with flow-induced vibrations in tube bundle heat exchangers was published in the VDI Warmeatlas (VDI 1997). Meanwhile there are some experiences with the use of this standard. Although the standard includes a large data basis in order to guarantee safety against flow-induced vibration there is still a number of uncertainties in it. E.g., in a number of experiments the authors were able to measure the hydrodynamic coefficient of tubes in tube bundles and found significant deviations between the results and the standard. Also the critical velocities were measured in the same tube bundles still showing deviations compared to the results of the standard up to a factor of 6.2. The explanation for this lies in the fact that it is not known which Eigenfrequency of a bundle might be dominating due to the influence of the baffle support gap. Moreover, one case was investigated by the authors where severe damage occured although the design should have been safe following the VDI Warmeatlas. Theretbre, for damping parameters lower than 0.3 the authors propose a revised form of Connor’s equation for stability. For a more exact investigation, the developement of numerical simulation codes is recommended and two examples for this are shown.Copyright © 2002 by ASME