Expansion joints effect a degree of isolation for equipment installed in piping. Expansion joints prevent the transmission of forces by allowing a degree of longitudinal or angular movement. Expansion joints are used to compensate for piping movements, whatever their origin, and also serve to keep other pipe sections free from vibrations. However, this functionality can only be performed to a limited extent.
Pressure forces which act in both directions cannot be absorbed by expansion joints alone but require the use of additional pipe anchorage points. When a pump is fitted to a pipe using an expansion joint, it is important to ensure that this expansion joint is equipped with a length limiter so that differential pressure forces cannot act upon the pump and shift it in the suction side direction on the foundation. These forces must not act upon the pump. Expansion joints are not capable of compensating surge pressures.