Rubber expansion joints are tubes made of elastomeric material, reinforced with multiple plies of fabric. The fabric reinforcement can be metal rings, wires, or solid metal embedded in rubber. Once the bellow is molded, the reinforcements and independent rubber layers are vulcanized. These vulcanized layers are used for a variety of applications.
FE modelling of rubber expansion joints
FE modelling has proven to be a useful tool for optimizing rubber expansion joints. The manual manufacturing process of mandrel-built expansion joints is extremely labour-intensive. TANIQ has developed a production system that automates the process, resulting in significant production time savings and a higher product quality. The new automated production line can be operated by a single operator. Training can be completed in less than a week.
A common problem associated with expansion joints is torsional movement. This can lead to failures when excessive torsional forces are applied to the joint. It is therefore important to design systems that do not place excessive torsional force on the joint. Another problem is pressure thrust, which can overcome the spring rate. This can cause specific failures in high-pressure systems. Furthermore, when the bellow does not have guidance or constraints, it can buckle.
Static analysis can include an expanded-pipe model, which involves simplification of the expansion joint and other components. The simplified expansion joint model can be used for static general analysis, as long as it includes the connection details. It is assumed that the expansion joint is responsible for axial extension of the fluid pipe. The expansion joint is then connected to a rigid connection on the free side, such as a concrete wall. Figures 6 and 7 show the stress and axial displacements of the expansion joint assembly.
The body of a rubber expansion joint is made of a protective lining of natural or synthetic rubber. The lining supports the joint for both pressure and movement. There rubber expansion joints are several different types of liners, and they are designed for different kinds of service. Some are designed for chemical and petroleum service while others are designed to protect against abrasive materials. The lining is made of a fabric, but some can also have metal reinforcement.
One of the most common applications of rubber expansion joints is in power generation. Power plants utilize them in coal-burning, hydroelectric, and nuclear heated facilities. Depending on the application, power plants may have several different fluid pipe systems, which use rubber expansion joints for their piping systems.
Typical materials used in rubber expansion joints
Rubber expansion joints are an ideal solution for many piping applications. These joints are available in many materials and can be shaped to meet a variety of needs. Typical materials used for these joints include natural or synthetic elastomers. They may also contain internal metallic reinforcements. These joints can be manufactured in two general types: universal and dual construction. They are designed to withstand the forces and movements that occur during mechanical expansion and contraction.
These joints are typically made of natural rubber, or synthetic oil-based elastomers. They can also be reinforced with metal, nylon, or polyester. Some rubber expansion joints are also made with PTFE lining to resist corrosive fluids and chemicals. These materials are extremely resilient and do not wear down under high pressure. PTFE expansion joints also have a low coefficient of friction and can flex and absorb forces that would damage metal joints.