How to Design a Rubber Expansion Joint

Rubber expansion joints are engineered products that provide protection to equipment from unwanted vibrations. They can be installed in a wide range of conditions and media, and their flexibility allows them to absorb large deformations. In addition, they also have excellent sound insulation properties. They can be used in many different systems, including buildings, chemical plants, and shipbuilding. They are available in both angular and torsional direction, and are manufactured from either natural or synthetic elastomers.

There are two types of rubber expansion joints: hand-built and mandrel-built. A hand-built joint has fixed metal flanges embedded in the rubber. This type of joint has a wider arch and lower spring rates than a narrow one. The mandrel-built ones have an arched shape and are made from heat-resistant synthetic elastomers. They are often used for applications in abrasive slurries or chemical environments.

Both types of rubber expansion joints are used to absorb movement. Unlike the spherical connectors, which are designed to absorb only small stress motions, style FTF joints are made for larger axial movements, such as those experienced by building construction, shipbuilding, and other industries that need to withstand a lot of pressure.

Typically, the elastomeric material used for the body of the joint is EPDM, Neoprene, or Viton. This expansion joint rubber is because these materials offer the best temperature resistance, and also have better physical characteristics. In addition, all of these elastomers are capable of resisting embrittlement, which is the leading cause of failure in expansion joints.

In addition, a layer of elastomeric epoxy is added to the exterior of the joint to form a secondary seal. This prevents contaminants from reaching the concrete. Control rod assemblies are optional, and may be necessary to avoid excessive movement. The control units can also act as a safety device in the event of an anchor failure.

The design of an expansion joint must be optimized for the application and the current production process. This can help to reduce the cost and increase the performance of the product. The use of Finite Element Analysis (FEA) has proven useful in optimizing the design of expansion joints. For example, FEA models have been used to optimize the design of rubber expansion joints, and the result has been an increase in machine speed and accuracy. The optimization has been validated by the results of product testing.

In the case of mandrel-built rubber expansion joints, a mold is used to form the joint. The material is then placed into the mold, which is then vulcanized. The result is an expansion joint that has unique consistency. All layers are then wrapped with a bias-cut fabric ply. This provides an interwoven layer that prevents the layers from delaminating.

Aside from being a cost-effective solution, rubber expansion joints are designed for ease of installation. There are numerous accessories for these joints, such as retaining rings, control units, and safety shields. There are also options to add solid rings or wire to the expansion joint’s carcass to support it.