Backup rings are commonly installed with O-Rings to improve their performance. Backup rings are useful for many different reasons but the main reason is by blocking or reducing the extrusion gap. This prevents the O-Ring inside to be damaged or extruded causing failure of some systems, especially in high-pressure situations. Generally, backup rings come in two different shapes, flat-sided and concave sides. The reason behind the introduction of the concave backup ring was to relieve the pressure off the O-Ring as it deforms under pressure. However, there are no real performance benefits from either a flat or concave backup ring.
Backup rings are used for many different industries around the globe. A few typical applications include hydraulic systems, high-pressure hydraulic systems, and high-pressure valves. In the majority of applications, it is often best to use two backup rings; one above and one below the O-Ring. This type of application will provide the best support for the O-Ring and allow for a smooth operation.
Spiral backup rings are overlapping and coiled material. The overlapping coil provides extra support under higher pressures. While these types of backup rings are not heavily used in modern systems, it is used for very specific purposes.
Solid backup rings are easy to install and are super popular when working with rods and pistons. Face seals use these quite often because of the easy installation.
PTFE Split, scarf cut, backup rings are the most commonly used backup rings today. They are easy to install, be made of harder materials, and handle extreme pressures. Because of the gap, it can easily be opened or closed to fit most extrusion gaps when needed.
These are anti-extrusion rings that can be used in both static and dynamic applications. They have contoured These are useful when certain clearances aren’t controlled.