CategoryPage
Home     Products Seals O-rings and accessories

Back-up Rings (3 products containing 573 Items)

Grid    
List    
1 / 1
  • ERIKS Back-up ring FKM
    Back-up ring FKM
    37 items
  • ERIKS Back-up ring NBR
    Back-up ring NBR
    286 items
  • ERIKS Back-up ring PTFE
    Back-up ring PTFE
    250 items
Grid    
List    
1 / 1

Back-up rings

In high-pressure applications, an O-ring can be forced out of the groove and squeezed into the seal clearance gap. This is known as extrusion. When this happens, the seal suffers damage and leakage occurs. A back-up ring, or anti-extrusion ring, prevents this type of unwanted movement.


In static applications, rubber O-rings with a Shore A hardness of 70 can be used up to a maximum pressure of 80 bars. Even so, we recommend the use of an O-ring with a Shore A hardness of 90 at pressures of 50 bars and above. At higher pressures, we advise you to use back-up rings as well.


In dynamic applications, back-up rings are required from 50 bars pressure. VMQ (silicone) seals are an exception to this rule. This type of material of the same hardness can withstand roughly half as much pressure. You should always strictly adhere to the guidelines on groove dimensions and the seal clearance gap.

Back-up ring dimensions

If you want to use an anti-extrusion ring, there must be enough room for it in the groove. Ideally, you should place the anti-extrusion ring in this space, next to the O-ring, thereby closing the gap where extrusion can occur. Note also that you must place the back-up ring on the side where there is no medium pressure.


If the O-ring is subject to load on both sides, install two anti-extrusion rings. If there is enough space, the use of a back-up ring on both sides is recommended anyway.


Our back-up rings are either offered in metric sizes or according to international standards, specifically AS568, BS1806 and ISO3601.

Back-up ring materials

We use various materials, such as NBR, FKM and PTFE, for the production of back-up rings. As with O-rings, you must ensure that your back-up rings are suitable for the conditions under which they will be used. So choosing anti-extrusion rings made of the right material is critically important. The summary below provides concise information about the most popular materials and their properties.

  • PTFE back-up rings

Most back-up rings are made of PTFE. PTFE anti-extrusion rings, also known as Teflon back-up rings, are highly resistant to strong acids and bases. However, this material is neither hard-wearing nor elastic.

  • NBR back-up rings

Many anti-extrusion rings are made from NBR, also referred to as nitrile. This rubber material is suitable for sealing lubricating oils and hydraulic oils. NBR back-up rings are not very resistant to ageing, UV radiation and high temperatures (above +120°C).

  • FKM back-up rings

An FKM anti-extrusion ring is the best solution for applications that involve extremely high temperatures. This material is capable of withstanding temperatures up to +200°C. Furthermore, these back-up rings are resistant to many strong acids and bases, but not to hot water or steam.


Would you like more information about the chemical resistance of our materials? Refer to our Chemical Resistance Guide for a handy overview.

Ordering back-up rings at ERIKS

When are back-up rings used?

Back-up rings are used to prevent extrusion of an O-ring into the clearance gap. This is necessary in applications with a pressure of 80 bars or higher. In such cases, you should also use an O-ring with a Shore A hardness of 90. Would you like to know more? Read our article on the causes of O-ring damage.

What prices does ERIKS charge for back-up rings?

The price of our back-up rings is shown on the product pages. If the price is not immediately visible, it will be displayed after you have logged in.

What delivery time does ERIKS offer for back-up rings?

The delivery time for a specific back-up ring is indicated on the page for that product. If you need your back-up ring faster, Choose a different material that also works in your application.

What if you have trouble finding a good alternative? Let us help - contact us via the enquiry form.

Can I order custom back-up rings?

Solid split back-up rings are available on request. The advantage of this type of back-up ring is that it is easier to install in the groove. For other specific requirements, please contact us via the enquiry form.