A heat-exchanger system consisting of a bundle of U tubes (hairpin tubes) surrounded by a shell (outer vessel); one fluid flows through the tubes, and the other fluid flows through the shell, around the tubes.Multitherm can duplicate any existing bundle to include dimensions, materials and performance. we can build “U” tube bundles, straight tube “floating” tube bundles, or we can retube fixed tubesheet heat exchangers when the bundles is not removable. multitherm is not locked into any one material. Most bundles tend to be build with copper tubes and steel tubesheets.