What is an expansion joint or bellows?

What is an expansion joint or bellows?

An expansion joint or bellows is a flexible component .which is used in the piping system to absorb the expansion, contraction, deflection, or bending in torsion in a piping system. The expansion joint or bellows is used at the piping connection to the equipment nozzle (Pump, compressor, turbines) to absorb deflection in the piping system caused by thermal expansion or contraction of pipelines. Thus Bellows absorbs the piping movements and safeguards the connected equipment from Transmission of excessive loads to the equipment nozzle from the joint piping system.

Bellows movements and the spring

Four basic types can relate on a bellows

Axial Movements

Lateral Movements

Angular Movements

Torsional Movements

 1. Axial Movement

Axial Movements of the bellows are the change in the dimensional length of the bellows from its free length direction parallel to its longitudinal axis. The Bellows compression (-) and bellows extension (+). The unit for axial spring rate is N/mm

2. Lateral Movement

The relative displacement of one end of the bellows to the other end in the direction is perpendicular to its longitudinal axis? Lateral movement is imposed on a single bellow but at a limited degree. To get more lateral movement two sets of bellows are the better solution. Unit of lateral spring rate is N/mm

3. Angular Movement

Angular Movements are the rotational displacement of the longitudinal axis of the bellows towards a point of rotation. The convolutions at the innermost point are in compress (-) convolutions at the finest point are extension (+) angular spring rate.

4. Torsional Movements

The rotation twisting of the bellows about its center axis. Torsional movement do stabilize the bellow and reduces its ability to absorb other movements such as axial and lateral