Expansion Joints for Heat Exchangers

Differential axial expansion between the shell and the tube bundle is a well-known problem in fixed tube sheet heat exchanger and pressure vessels design.

In heat exchangers, inner tubes and shells frequently do not expand at the same rate due to differences in the materials used, varying temperatures, and other factors. If the heat exchanger is not prepared to control this longitudinal thermal expansion, pressure and dimensional changes in the tubes or shell can cause significant damage to the unit.

Expansion joints are promising for accommodating differential thermal expansion of heat exchanger shells. Differences in the axial expansion of the shell and the tube bundle due to high mean metal temperature differentials warrant incorporation of expansion. This is particularly true for fixed tube-sheet exchangers.

In most cases, the internal tubes of exchangers are made of nickel alloys or stainless steel material which means that they expand approximately 50% more than carbon steel, which is the material from which the shells are usually manufactured.

The most optimal way to manage and control the differences in thermal expansion between tubes and shell is with the installation of expansion joints in the outer shell.