We test our anti-extrusion ring at the Polytechnic University of Catalonia

From Epidor Seals and Rubber Technology we have tested our anti-extrusion rings in the test bench located in the research laboratory of the Fluid Mechanics Department of the Universitat Politècnica de Catalunya (UPC).  And the results were all a success!

Also, in this weekly post, we look at how extrusion can affect equipment and delve into the functions of an anti-extrusion ring working in hydraulic applications.

What is the function of the anti-extrusion ring?

In applications where high pressure stresses are found, or even in assemblies where the extrusion groove is of considerable dimensions, it is common to find assemblies where profiles that incorporate a ring on the back side. This ring is known as an anti-extrusion ring.

The main function of this sealing solution is to prevent extrusion of the seal, caused by the high pressure it has to withstand. Extrusion can occur at these two points:

1. Extrusion groove in stem:
   
2. Extrusion groove in piston:

The anti-extrusion ring can be found in both static and dynamic mountings, O-rings and/or U rings.

Our anti-extrusion ring passes UPC tests with ease

Supported by the test bench we have at the UPC facilities in Barcelona, we have subjected our anti-extrusion rings to a series of tests to ensure that they comply 100% with their function.

Below is a diagram summarising the conditions of this test which aims to confirm the sealing performance of the anti-extrusion ring:

• 1. Two equal profiles were assembled, one without an anti-extrusion ring and one with a ring. The profiles are as follows:

DS101 40x50x10

DS102 40x50x10

1. 2. To further exemplify the results, the two profiles were manufactured in soft material and the ring was machined in POM. Afterwards, a 50,000 cycle test at 200 Bar was launched.
2. 3. Once the test was completed, the system was disassembled and it was observed that, in the housings where the parts without the anti-extrusion ring were installed, gasket remains appeared, as can be seen in the image.

A visual comparison of the images of the two gaskets below shows the extrusion suffered by the gasket without the anti-extrusion ring:

In short, the seals designed and manufactured by our team have proven to withstand the sealing tests in the series of trial runs to which they have been subjected on the UPC test bench.

The effects of extrusion can be devastating for equipment

In all our technical data sheets we indicate the maximum permissible extrusion grooves depending on the application pressure and shaft/piston diameter for the most common materials. A good initial design is the best guarantee to avoid future problems and production stoppages due to problems with the equipment in the plant.

At Epidor Seals and Rubber Technology we have a team of engineers to advise our customers on hydraulic system housings and finishes.