The rubber joint is a type of flexible, non-metallic connector used in piping systems to isolate vibration and compression. It provides resistance to erosion, abrasion, and corrosion. It is widely used in process piping and ship building industries. It is also used in sewage treatment plants and urban heating and air conditioning systems. It is very durable and reliable.
An expansion joint has three parts: the body, the cover, and the pressure bearing layer. The body consists of the fabric that supports the joint while it is in the open. The cover is made of natural or synthetic rubber to protect the joint from external damage. The cover is designed to resist chemicals, sunlight, and oils. It can be manufactured to resist acid fumes. The cover should be leak-proof and contain a secondary seal.
The cover can be designed to protect the rubber expansion joint from acids, abrasions, and corrosion. The joint can be installed on flanges with a flat face or raised face. It is usually reinforced with metal. The inner tube is also made of natural or synthetic rubber and extends through the bore of the joint to the outside edges. This is to prevent the materials from penetrating the carcass. The joint is typically designed to accommodate a bend.
The DA style is the most economical of the dual arch types. This design has a long radius arch that can be self cleaned. It is also a simple installation option. The joint is available in a single sphere or double sphere.
The clamp type rubber joint is less complicated to install and maintain than the DA style. It has fewer parts and has simplified the production process. Its advantage is that the raw material is saved. The clamp type also promotes the working efficiency of the joint. However, rubber joint it is not suitable for all applications.
A spherical joint is usually too rigid to handle large deformations. Hence, it is generally reinforced with solid metal rings or wire. This can raise the rated working pressure. For this type, the rated working pressure should not exceed a certain percentage of the pressure thrust force. The pressure thrust force is the total force on the pipe anchor and is added to the spring force.
The most common failure in a flexible rubber expansion joint is due to the failure of the rubber. This can be attributed to plasticization, hardening, or temperature. It can also be attributed to incorrect installation. Therefore, the joint should be installed in accordance with the installation instructions, and inspections should be performed to ensure that the installation was done correctly. The joint should be installed in neutral length and should be inspected to ensure that there is no excessive misalignment between flanges. It should be replaced if any leakage is seen.
When designing a flexible rubber expansion joint, the axial elongation should be less than the lateral elongation. The angular elongation should be less than the transverse elongation. The axial extension lengthens the joint along the longitudinal axis.
