Pressure balanced expansion joint is used most frequently in applications similar to those shown for the single expansion joint, but where pressure loading up on piping or equipment is considered excessive or objectionable. The major advantage of the pressure balanced design is its ability to absorb externally imposed axial movement without imposing pressure loading on the system.
Where large amounts of lateral deflection are involved, a pressure balanced universal expansion joint must be used. Two bellows are used in the flow end of the expansion joint and a single bellows in the balancing end. Normally, the balancing bellows will be subjected only to axial movement if the tie rods are properly designed to rotate or pivot at their attachment points.