Expansion joints expand in length when under pressure. The force created by this pressure is designated as Pressure thrust. Where the pipe supports and anchors are not designed to absorb this force, tie rods across the joint must be incorporated. Tie rods are designed to take the full pressure thrust and tie rods supports are integrated in the flanges (retaining rings) so there is no thrust on counter flanges.

Recommended on most applications to prevent damage due to excessive pipe movements, each rod incorporates double nuts on each end to keep the expansion joint from over elongating and spherical washers to allow lateral and some angular
movements (2 tie rods only).