Rubber expansion joints are used in piping installations to compensate for thermal growth, relieve piping stress during operation, and reduce vibration and noise caused by rotating equipment. While a rubber expansion joint can compensate for pipeline misalignment, this compliant product has installation and operational limitations. The best method for installing most piping products, including rubber expansion joints, is to follow standardized piping practices and use an installation tolerance of less than 1/8 inch (in.). Using a rubber expansion joint when the piping misalignment will be more than 1/8 in., however, requires special considerations. One standard practice is to use a concurrent movement calculation to ensure that the installation of the product does not use too much of the joint’s ability to compensate for movement. The concurrent movement formula established by the Fluid Sealing Association’s (FSA) Rubber Expansion Piping Division Edition 7.31 can help designers determine engineering needs and the allowable offset for piping installers. In addition, designers should write adequate construction notes for piping installers.
- Compression
- Elongation
- Lateral or transverse
- Angular
- Torsional