Expansion Joints are used to absorb dimensional changes caused by thermal expansion or contraction of a pipeline, duct, or vessel while containing the system pressure. The flexible element of the expansion joint that expands or contracts to absorb thermal movement is called Bellows. It consists of one or more convolutions.
Piping Expansion Joints serve various purposes when installed in a piping system. Those are:
- To absorb movement (Thermal expansion as well as compression)
- To relieve system stress and strain.
- To reduce mechanical noise and vibration.
- To have a compact design (space constraint)
- To compensate for misalignment.
- To eliminate electrolysis between dissimilar metals.
- To reduce piping loads on equipment nozzles.
The main components which constitute an expansion joint are as follows:
- Bellow
- Tie Rods
- Flanges
- Shipping Bar
- Protective Covers and Internal Liners
- Special Attachments like Pantographic linkages, etc
Expansion Joints used in industry are designed, manufactured, and tested in accordance with the following Codes and Standards
- EJMA, Expansion Joint Manufacturer Association, Inc.
- ASME B31.3 Appendix X, Metallic Bellows Expansion Joints
- ASME Sec. Ⅷ Div.1, App.26.
- EN 14917 Metal Bellows Expansion Joints for Pressure Applications