In any piping system, there is a degree of flexibility inherent in the design. This flexibility results from change in direction of the pipe system as it connects the various components to each other. This inherent flexibility may be insufficient, in which case it becomes necessary to develop additional flexibility. This can be achieved by locating Expansion joints at strategic points in the system. Expansion joints help in reducing stresses in the pipe and forces at the anchors, to accommodate  the strains of thermal growth in a restricted space.

The previous method of achieving flexibility, by creating pipe loops or direction change, is more costly than the use of Expansion joints, because of piping material, space problems, pressure drop, increased power requirements, for fans, blowers, etc. This can be eliminated by the use of "Bellows Expansion Joints".