Expansion joint rubber is an effective material for a variety of piping applications. It can be used as an expansion joint rubber to take up thermal growth and temporary pipe movements, or as a flex connector to absorb noise and vibration from mechanical equipment that is next to the pipeline. These products can be manufactured with a variety of construction features, including steel or aluminum rings or fluoroplastic liners.
Sphere and Spool Type Joints
Spherical expansion joints are made from either single or double rubber spheres that are molded in hydraulic molds. They are available in a wide range of sizes, from 1-1/2 inch to 36 inches diameter. They are a good choice for absorbing small pipe motions, such as the movement of water in HVAC systems.
Spool-type rubber expansion joints are made in a variety of styles and sizes, from a single wide arch to multiple arches that can be built to absorb even greater pipe movements. They are made from a high-pressure reinforcing of polyester fabric plies along with steel hoops for vacuum ratings, and are wrapped with a rubber cover to protect the reinforcing.
These are the most commonly manufactured rubber expansion joints in the world, and they can be customized to meet specific needs. Typically, they are reinforced with polyester fabric plies and steel hoops for working pressures up to 150 PSI and vacuum ratings up to 225 PSI.
They are also made with fluoroplastic liners to resist chemicals in the temperature range of the product’s construction. This can be a critical factor when a product is exposed to the chemicals in the fluid that the pipe system may be conveying, as well as corrosive liquids and gases.
The spool-type is also manufactured with an arc design, which increases its capacity to take up large deformations. This is especially useful for piping misalignments that cannot be corrected with a simple flanged joint, as it is able to maintain 100 percent of its movement absorbing capability.
Style 1200 “Flexi-Spool” Rubber Expansion Joints
Designed to handle a multitude of industrial applications, style 1200 “Flexi-Spool” rubber expansion joints are hand-wrapped, wide-arch-style joints that can take up several times the movement capability of narrow-arch-style joints. They feature a high-pressure reinforcing made from both polyester fabric plies and steel wire for impressive working pressure and vacuum ratings, while a thick, wrapped-on rubber cover protects the reinforcing from damage or contamination.
A special feature of this joint is that it can be filled with a rubber foam if needed, which helps to absorb media that might clog or degrade an open arch. It is an economical option for high-pressure applications that do not require the high pressure and vacuum ratings of a full-face joint, but still need the wide range of movement capability of an arch-style joint.
In addition to a wide variety of construction options, some rubber expansion joints can be fabricated to field dimensions for offset installations where piping misalignments are difficult to correct in the field. These can be very helpful for reducing costs and time in a project, but should be used as a last resort when precise measurements are not possible.