Rubber-Edged Composites: A Unique Approach to Reducing the Effects of Compression Stress Relaxation on Static Rubber Seals

Static rubber seals are common in bolted flange joints. These seals share the feature that, during assembly, the seal compresses until there is metal-to-metal contact. Examples include O-rings in grooves, metal carrier gaskets, or metal grommets at bolt holes. It is this “fixed compression” of the rubber that creates the optimum initial sealing stress within the rubber. However, a rubber seal will relax over time and, as the sealing stress decreases, leaks can develop. Since further compression of the rubber over time is prevented by metal-to-metal contact, there is no mechanical remedy for this type of failure.

Rubber-edged composite seals have a rubber seal on the inner edge of a composite carrier. This is a completely new type of seal construction. The dynamics of joints using this sealing solution are different from the dynamics of joints using “fixed compression” sealing solutions. With certain rubber-edged composite seals, as the rubber sealing edge relaxes over time, so does the compressible carrier. This creates additional compression of the carrier that causes a further compression of the rubber edge-seal, thereby maintaining or restoring sealing stress within the rubber.