AS568 O-Ring Standard (SAE/ANSI)
Also known as: AS568A · AS568B · SAE AS568 · dash number
AS568 (SAE Aerospace Standard) defines 369 standard O-ring sizes in inch dimensions — each identified by a dash number (e.g. -214) specifying inside diameter and cross-section width.
Technical Detail
AS568B (current revision) covers O-ring sizes from -001 (0.029 in ID × 0.040 in W) to -475 (18.968 in ID × 0.275 in W), plus boss seal and face-seal series. The dash number directly encodes the size class: -0xx are face seals; -1xx to -4xx are standard O-rings sorted by cross-section (1/16, 3/32, 1/8, 3/16, 1/4 in W). Common sizes in industrial flanges: -214 (1.489 in / 37.8 mm ID, 2.62 mm W), -222 (2.237 in ID), -230 (2.984 in ID), -238 (3.734 in ID), -250 (5.237 in ID). AS568 groove dimensions are specified in the standard Appendix A — groove depth, width, and diametral clearance for static and dynamic duty. Used predominantly with ANSI/ASME B16.5 flanges (class 150–2500) and JIC/SAE hydraulic fittings.
Reference Standards
- SAE AS568B
- ANSI/ASME B16.5
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