Abstract: For U-tubular or floating head heat exchangers with multiple tube passes, large temperature difference between inlet and outlet of tube pass, high pressure and tube-sheet clamped by channel flange and shell flange, leakage often occurs at the channel flange. Based on the analysis of flange sealing mechanism and the influence law of internal pressure, pass partition, channel temperature and circumferential temperature gradient on the gasket residual compression pressure, this paper expounds the inevitable causes of local leakage on the sealing surface of the channel flange of this kind of heat exchanger, and puts forward the preventive and remedial measures to prevent this kind of leakage accordingly. In particular, taking the successful anti-leakage design of a heat exchanger with harsh working conditions in engineering as an example, the paper introduces a complete set of preventive structure optimization design method.

Key words: heat exchanger, circumferential temperature gradient, flange, residual specific pressure of gasket, anti-leakage measures, structure optimization