There are four basic movements that can be applied to a bellows. These are Axial, Lateral, Angular and Torsional. SHAH ENGINEERS (I) is able to vary bellows geometry such as convolution height, pitch, thickness and number of plies to provide a bellows to satisfy our customer's needs.

Axial Movement
Also know as: Compression, Extension Axial movement is the change in dimensional length of the bellows from its free length in a direction parallel to its longitudinal axis. Compression is always expressed as negative (-) and extension as positive (+)

Lateral Movement
Lateral movement is the relative displacement of one end of the bellows to the other end in a direction perpendicular to its longitudinal axis (shear). Lateral movement can be imposed on a single bellows, but to a limited degree. A better solution is to incorporate two bellows in a universal arrangement. This results in greater offset movements and much lower offset forces.

Angular Movement
Angular movement is the rotational displacement of the longitudinal axis of the bellows toward a point of rotation. The convolutions at the inner most point are in compression (-) while those furthest away are in extension (+).



Torsional Movement
Torsional movement is the rotation about the axis through the center of a bellows (twisting). EJMA DISCOURAGES ANY TORSIONAL ROTATION OF METAL BELLOWS EXPANSION JOINTS.

Vibration
This can be either one or a combination of four types of movements described above under a variable or constant frequency. Vibration is always undesirable in a piping system and often bellows type Expansion joints are used to dampen vibration. It is essential to know the magnitude of movements and the frequency of the vibration in the system.