Compression Set

Description: The o-ring or seal exhibits a flat-sided cross-section, the flat sides corresponding to the mating seal surfaces.

Contributing Factors: Excessive compression. Excessive temperature. Incompletely cured elastomer. Elastomer with high compression set. Excessive volume swell in chemical.

Suggested Solutions: Low compression set elastomer. Proper gland design for the specific elastomer. Confirm material compatibility.

Outgassing/Extraction

Description: This failure is often very difficult to detect from examination of the o-ring or seal. The o-ring or seal may exhibit a decrease in crosssectional size.

Contributing Factors: Improper or improperly cured elastomer. High vacuum levels. Low hardness/plasticized elastomer.

Suggested Solutions: Avoid plasticized elastomers. Ensure all seals are properly post-cured to minimize outgassing.

Installation Damage

Description: The o-ring or seal or parts of it may exhibit small cuts, nicks or gashes.

Contributing Factors: Sharp edges on glands or components. Improper sizing of elastomer. Low-modulus/hardness elastomer. Elastomer surface contamination.

Suggested Solutions: Remove all sharp edges. Proper gland design. Proper elastomer sizing. Higher-modulus/hardness elastomer.