Tied Expansion Joints required to accept large amounts of lateral movements. Because tie rods are provided to resist pressure thrusts, these joints cannot accept axial movements. Also, if more than two tie rods are used, angular movements are not accepted. The tie rods are usually at or near ambient temperatures and therefore do not expand and contract as a function of the temperature of the media within the pipe. As a result, the thermal expansion of the length between the tie rods occurs within the expansion joint and is not applied to the rest of the piping system. The bellows design must accommodate this axial thermal expansion as well as the lateral movement for which the expansion joint is needed.