With the advancement of welding technology, most of the connection methods of titanium heat exchanger tube bundles, tubes and tube sheets are welded or expanded. Weld leakage between tube and tube sheet is a difficult problem in tube bundle leakage treatment. Repair welding is not a good method, because there are impurities in the hole gap between the tube and the tube sheet during use, which makes strong bubbles, slag, interlayer and local stress concentration caused by welding formed during the welding process. , cracks may appear near the repair welding nozzle, causing new leaks.
Therefore, in terms of the strength of welded titanium heat exchanger tube bundles, the way to avoid the failure of the solder joints: one is to reasonably select the material, that is, to reasonably select the tube sheet and the heat exchange tube according to the medium, especially to avoid the electrical connection between the tube sheet and the tube. chemical corrosion. Secondly, the root of the weld should ensure the welding penetration and have a high enough strengthening height (≥2.5 mm). Furthermore, production practice shows that the strength of solder paste expansion is the key to ensuring that the solder joints of titanium heat exchangers do not fail.
For pure-strength expansion tube bundles, if the expansion port leaks, it can be supplemented after pressure relief, and the number of supplementary expansions shall not exceed three times.
