A rubber expansion joint is a flexible connector that absorbs shock, vibration, physical and thermal energy. Made from natural and synthetic elastomers, it may be internally reinforced with fabrics and metal for strength and pressure resistance or externally for movement control.
The design and material selection of a rubber expansion joint are critical to its life and performance. Its ability to absorb and accommodate pipe movement, misalignment, and vibration allows the piping system to function properly and protect the connected equipment from damage.
Its flexibility can also be used to isolate and reduce noise and vibration. It can also be designed to absorb abrasion and chemical erosion within a fluid system, which helps to prevent contamination of the system from these materials.
Several different types of rubber expansion joints are available, including double-protected designs that provide superior protection and long life. These are designed with a leakproof tube and flanged flanges that are coated with special urethane formulation for additional resistance to aging.
This type of expansion joint can be used in many ducting systems, including those found in power plants, gas turbines, pumping systems, and industrial processes. It is especially beneficial in systems that handle abrasive slurries, corrosive chemicals, or extremely reactive liquids and gases.
The elasticity of rubber makes it able to accommodate large axial movements (compression and extension) as well as lateral deflection and angular movement in a much shorter face-to-face dimension than steel. This allows for the joint to recover from these imposed movements with minimal force and minimizes the risk of damage to piping, pumps, and other motive equipment.
A wide range of natural and synthetic elastomers are available to meet the demands of different applications. These can be treated and mixed to give high performance with resistance to abrasion, chemical attack, oil, sunlight, acid fumes and ozone.
The flexibility of rubber expansion joints allows them to be designed with arches or bends that help to increase their capacity to accommodate movement in a variety of directions. This can result in a significant cost savings for the piping and system designer because it eliminates the need for separate constructions for axial, lateral, and angular movements.
Other design features can also be incorporated to enhance the performance of a rubber expansion joint, such as:
It is important for the design and installation of an expansion joint to take into account any barriers or interferences that may be present next to the ducting or pipes it is attached to. This can include obstacles or obstructions in the ducting, such as a clogged vent pipe, or any object that might prevent the expansion joint from being mounted on its proper location.
This is particularly important for the application of an expansion joint in a concrete structure because of the potential for damage to the concrete and to the surrounding environment. The proper placement and spacing of a control joint can minimize this potential, especially when the joint is installed before the concrete has been poured.