Heat Hardening & Oxidation Damage
Hardening and oxidation occur when the part is exposed to high temperatures for an extended period of time, causing plasticizer volatilization and oxidative cracking. As the O-ring material hardens, the O-ring is unable to retain sealability, causing leakage and failure to occur.
When the temperature in or around a system is considerably heightened, the seals are more likely to fail. Lubricants and plasticizers are more susceptible to volatilization and thus the seal becomes less flexible. Continuous exposure to elevated temperatures most frequently results in permanent compression set (seal deformation, see video below), resulting in loss of seal memory and sealing force retention.
Forms of Excessive Heat Damage