Expansion joints are simply an assembly of bellows with other components to form a product that can contain movements caused by stress, thermal stress, and other seismic activities. They can be classified into multiple types based on their design, functions, and so on. Some of the common types are axial, lateral, hinged, gimbal, universal, elbow pressure balanced expansion joints and so on. Universal expansion joints are one of the most important and most used types of expansion joints.
The reason behind the widespread usage of universal expansion joints is that unlike a lot of the other types, these can contain movements in all 3 directions namely lateral, axial, and angular. Also known as a double bellow expansion joints, these are made with 2 bellows that are connected by a spool or pipe section. Another major advantage of using this over others is that large amounts of lateral deflection can be absorbed with this. If the capacity has to be increased, this can be done by increasing the length of the pipe section connecting the 2 bellows. In certain cases, tier rods may be attached to limit the axial expansion. If 2 tie rods are used, it can take in good lateral and angular expansion. By using more than 2, you can make the expansion joints to contain only lateral expansion.
Be careful while handling the product. It is important to ensure that there are no dents, weld splatter, etc on them.
The joint is not made to rectify misalignments in the piping system. As a result, you must not use them to do the same. Imposing unnecessary movements to align can reduce the life cycle and capability.
If any sleeves, flanges, etc. are required, you must attach them properly.
Store in a cool dry place and not exposed to heavy traffic and a damaging environment.
While lifting, do not use ropes or rods through the holes. Use proper lugs instead.
Install the product in the direction of flow.
Do not subject it to heaving torsional forces.
Do not use steel wire, mesh, and other abrasive cleaning products on the surface.
Before testing, ensure that you remove all the shipping devices and packaging.
Align the bolt holes with ones matching on the mounting flange.
Do not use cleaning products that contain Chlorides
Do not expose the product to more than one and a half times its rated working pressure.
Check for any evidence of leakage or loss of pressure.
Check for any distortion of the expansion joint hardware, the bellows and other piping components.
Check for any possible squirm in the product.
If there are any abnormalities during the testing, it must be evaluated by the concerned authority.
Just like the checks and inspections before installation, it is extremely important to check the product while it is in service to ensure a successful and smooth functioning.
Inspect the product to check if it is functioning as planned by the manufacturer, as well as any unwanted vibrations.
Periodic inspection must be done. The frequency of this must be decided based on the working conditions.
Through these inspections, the product must be checked for any loose components, any deformations, corrosion on the surface, as well as any other damages.
If required, the components must be replaced or repaired as decided by the design team.
Improper handling during shipping
Corrosion of bellow elements
Higher working conditions that what is designed for
System fatigue, etc.
Generally, the expansion joints are not made to sort out the misalignments. However, if there are small deflections, you may contact the manufacturer and tell him beforehand.
Wide temperature ranges
Better performance than other expansion joints
Absorbs large degrees of lateral movement.