Gallagher recently released its Expansion Joint Design Guide, now available for download on our site. This design guide takes an in-depth look at elastomeric, metal, and flue duct expansion joints. The excerpt below is a section of our Expansion Joint Design Guide focusing on types of metal expansion joints. To download the entire guide, visit our Resources Page, or click on the image to the right.
Much like elastomeric expansion joints, metal expansion joints are used to preserve the integrity of a piping system where the piping is subject to changes in temperature, pressure, vibration, compression, extension, cyclical movements or movements required by usage.
Oftentimes, metal expansion joints are used when an elastomeric joint simply cannot handle the extreme conditions - applications where high temperature, large temperature range, or high pressure exists. Generally, metal expansion joints can be used from -450°F to +2000°F, depending on the metallurgy, and can also handle pressures from full vacuum to 3,000psi.
Metal Expansion Joint Components
Though customized and intricate expansion joints can be manufactured for a variety of specialized applications, there are four basic designs that are most commonly used:
Basic Bellows
A bellows can be supplied without end fittings for field installation. The skirt, or straight portion at each end of the bellows, can be sized to fit a flange or pipe. Skirt length can vary depending on your needs and should be specified when ordered.
Unrestrained Single
An unrestrained single expansion joint is best used by piping systems which are equipped with proper guides and anchors to absorb axial, angular, and a small amount of lateral movement.
Limit Single
A limit single expansion joint is best used when main anchors and guides are in the pipeline. While some axial movement and lateral movement are acceptable, the hardware protects the expansion joint from exceeding its design movements.
Tied Single
A tied single expansion joint is best used in piping systems without a main anchor. It allows for lateral movement only while also restraining pressure thrust.
In addition to the four basic designs, there are numerous other designs currently in use:
For more information about metal expansion joints, or about any of your expansion joint needs, please Contact Us today, and one of our engineers would be happy to assist you.