In a piping system a expansion joints alternately known as Bellows are like sealed springs. Sealed because it is required to contain the fluid pressure which is flowing through it and spring because it is required to respond to the movement of the connected piping without offering appreciable stiffness to the piping system.
Pipe Expansion Joints
An expansion joint/bellow element employed in a piping system is an assembly of generally more than one convolute in series. The convolutes are designed strong enough to withstand the internal pressure of the system, at the same time the typical contour of the convolute assembly allow sit to flex under thermal movement of the connected piping. As a result of this extreme flexibility the expansion joint / bellow as such is highly incapable of absorbing any longitudinal loads by its own,thereby requiring external attachments to transfer these longitudinal loads to its connected piping for maintaining the overall stability of the piping system under question.
Pipe Expansion Joints
Common types of expansion joints are:
- Simple Expansion Joint
- Universal Expansion Joint
- Pressure Balanced Expansion Joint
- Hinged Expansion Joint
- Gimbal Expansion Joint
The Bellows are generally employed in a piping system in one of the following situations:
1.When the space constraints do not permit providing adequate flexibility by conventional methods (e. g. expansion loops etc.) for maintaining the system stresses with in acceptable limits.
2.When conventional solutions (e.g. expansion loops etc.) create unacceptable process conditions (e.g. excessive pressure drop).
3.When it is not practical to limit the piping induced loads on the terminal nozzles of the connected equipment within admissible limits by conventional methods.
4.When the equipment such as compressors, turbines, pumps etc. necessitate isolating the mechanical vibrations from being transmitted to the connected piping.
