The back up ring, also called anti extrusion ring, is aptly named as they do just that: they back-up an O-ring.

The purpose of using the backup ring is to prevent the O-ring from extruding into the sealing gap under the system pressure. The structure of the increased back up ring will bear much higher pressure than using the O-ring alone.

The profile shape of the back up ring is usually rectangular but may also be concave at the face mating with the O-ring.

There're mainly 3 types of back up rings (based on the geometries):

1.Solid (uncut)

2.Single turn (scarf cut)

3.Multi-turn (spiral cut)

Backup rings are used for many different industries including hydraulic systems, high-pressure valves, and oil and gas field. 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. In the oilfield of demanding working conditions, PEEK back up rings can be used in multiple down-hole drilling applications where pressures can be up to 5,000 psi and temperatures often approach 350°F.

PEEK back up ring can function at the same level as a metallic back-up ring, without the risk of metal-to-metal contact which could potentially gall the hardware.

Materials of back up rings are chosen as per the applications. JST can provide back up rings with suitable material for a variety of unique applications. PEEK, PTFE, FKM, HNBR, NBR are available in JST.