A floating head heat exchanger, in which only one end of the two end tube plates is fixed to the shell, and the other end can move freely relative to the shell, is called a floating head. The thermal deformation of the tube bundle and the shell is not mutually constrained, so no thermal stress is generated. Its advantage is that it is easy to clean between and inside the pipes, and does not generate thermal stress; Suitable for situations where there is a large temperature difference between the shell and the tube bundle, or where the shell side medium is prone to scaling.