The Shell & Tube heat exchanger according to TEMA standard is made up of a bundle of tubes with two tube plates in a cylindrical shell, inlet, return and outlet chamber and inlet and outlet nozzles for fluids. The heat exchanger design is adapted to the requirements, e.g. both fixed tube plates or one fixed and the other floating tube plate, chambers fitted with flange connection or welded to the shell, etc. The design can be based on a horizontal or vertical position. These exchangers find wide-ranging applications.