Extrusion & Nibbling

Failure Pattern: Typical of high pressure systems, this pattern can be identified by the many small bites (nibbles) taken from the O-ring on the low pressure (downstream) side.

Problem Sources: Excessive clearances... Excessive system pressure... O-ring material too soft... Degradation of O-ring by system fluid... Irregular clearance gaps caused by eccentricity... Improper machining of O-ring gland (sharp edges)... O-ring size too large for gland.

Suggested Solutions: Decrease gland clearances by machining... Use back-up rings to prevent extrusion... Use harder O-ring material... Re-check elastomer compatibility with system chemicals... Increase rigidity and improve concentricity of metal components... Break sharp edges of gland to a minimum radius of .005"... Install proper size O-ring... Consider a reinforced composite seal such as rubber-bonded-to-metal.