Aerospace Size Standard for Oversize O-rings
This SAE Aerospace Standard (AS) is applicable to military and commercial aircraft. It specifies the dimensions, tolerances and size codes (dash numbers) for use in glands per MIL-G-5514 where squeeze at low temperature is often insufficient to provide a leak-tight seal. The dimensions and tolerances specified in this standard are suitable for any elastomeric material. This standard should not be used as a part standard, therefore no part numbers like AS5798-001X shall be created. Each dash number, which should be appended to an appropriate drawing or standard number, identifies one size O-ring only. An AS5798 sized O-ring is intended to replace an AS568 sized O-ring of the same dash number. An X suffix is part of the dash number to signify oversize. Temperature limitations of 275 °F (135 °C) and coefficient of thermal expansion of 9.0 x 10⁻⁵ unit length per °F (1.6 x 10⁻⁴ unit length per °C) were used for swell calculations. Applications that exceed these values should be evaluated for excessive gland fill.