A rubber joint is a flexible connector fabricated of natural or synthetic elastomers, fluoroplastics and fabrics with internal metallic reinforcements designed to absorb movements in a piping system while containing pressure and a medium running through it. They can be used to relieve stress from thermal growth, mechanical movement, vibration and noise, compensate for misalignment and provide shock loading and wind and seismic movement relief.
They are primarily a vibration dampening device but can also contain pulsation and directional movement in a piping system. They are used for a wide range of applications and are often preferred over metal expansion joints due to their resistance to abrasion, erosion, corrosion and noise and vibration.
Expansion joints are available in many shapes and sizes depending on the application. Standard spool style rubber expansion joints feature a cylindrical body, reinforcing rings, and a full-face flange. Spherical type rubber expansion joints have a spherical body, floating flanges and a bead seal instead of a full-face flange.
Typical materials for rubber joint include EPDM, IIR, NBR, and PTFE depending on the fluid being served. These materials offer excellent resistance to abrasion, chemicals and corrosive fluids. They can also resist heat, sunlight, acid fumes and ozone.
There are a variety of spool-type and spherical-type rubber joint types, as well as special designs for specific installation requirements. The spherical type provides a larger surface area than the cylindrical style.
They are able to accommodate a higher pressure than the standard metal joints and can be manufactured in single, multiple or custom arches. They are resistant to corrosion, abrasion and erosion in a variety of conditions and may be provided with hot-dipped galvanized retaining rings.
These joints are light in weight and require minimal face-to-face dimensions. This allows for easier handling and installability compared to metal joints and reduces plant space and labor costs.
The bellows are made of a resilient elastomer material. These elastomers are not susceptible to fatigue/cycle failure like metal expansion joints, making them more durable and longer lasting in the long run.
FEA simulations have been conducted for optimizing rubber expansion joints to handle large movement compensations in both lateral and axial directions. Using these simulations, optimal bellow shapes and the required number of bellows have been derived.
Mandrel-built rubber expansion joints are traditionally hand fabricated using steel mandrels, rubber bellows and flange rings. TANIQ has developed processes and equipment to automate the production of these joints, significantly reducing the time required for manufacturing these products by up to 70% in some cases.
Smart Point Filtering and Path Optimizations – FEA Analysis for Optimal Bellow Shapes
A digital three-dimensional design, combined with Finite Element Analysis (FEA), can be used to optimize the design of the joint for performance and economy. FEA can also be used to identify smart rubber-to-cord meshing strategies to lower the required amount of reinforcement.
This can save up to 50% of the required reinforcement materials, resulting in reduced costs and improved performance.