Ask the Experts

We experienced seal failure in a natural gas application and noticed a number of splits or cracks in the O-ring. What might be the cause?

In high pressure gas applications, a common problem is explosive decompression. This problem is indicated by the random short splits or ruptures going deep into the O-ring cross section. When the O-ring is first removed, the surface may also be covered by small blisters. Explosive decompression typically occurs when a gas is absorbed by an O-ring while operating in high pressure: the gas is trapped within the O-ring when the system pressure drops, causing the surface of the O-ring to blister and rupture as the trapped gas expands. In this situation, an O-ring with the smallest possible cross section should be used, as well as a rubber compound with low permeability.

How do I know which elastomer to specify when ordering seals?

For virtually every O-ring end use, the selection of elastomeric material is contingent upon a number of design factors such as: dynamic or static application; chemical compatibility; the O-ring's ability to resist pressure, heat, cold and friction, and consideration of material availability and cost. In addition to design factors, of course, you should also consider the nature of the installation, the use of the product and the kind and degree of maintenance that may reasonably be expected.

With such a multiplicity of design factors to consider, it is possible for several O-ring materials to meet, or nearly meet, your specified application requirements. In the case where several O-ring materials meet your requirements, cost and availability may be the deciding factor.

Click here for more information on material selection.

A stainless steel component in our product is covered with small pock marks around the seal area. Where are they coming from?

More than likely, the seal features a graphite compound for durability. You should avoid using graphite-loaded compounds with stainless steel, as they tend to pit the stainless seal surface over time.

Ask the Experts yourself

If you've got sealing questions, you can Ask the Experts at Apple Rubber for answers. Submit your question or questions using our Engineering Assistance Request form and we will respond as quickly as possible.