Complete AS568 and metric O-ring gland design charts for static face seals, radial piston/rod seals and dynamic reciprocating applications. Instant lookup of groove depth, width, corner radius and recommended squeeze percentages.
Select the O-ring cross-section (CS) series that matches your seal. Use the static tables for face seals and stationary radial glands. Use the dynamic tables for reciprocating piston or rod seals. All dimensions follow mainstream industrial references including the Parker O-Ring Handbook (ORD 5700), SAE AS568 and ISO 3601 guidelines.
Values are nominal starting points. Always account for tolerance stack-up, fluid swell, thermal expansion and maximum extrusion clearance under your working pressure and material selection.
Recommended gland depth and width for static face seals and static radial seals. Typical squeeze range: 15–30 %.
| CS Series | Cross-Section (in) | Gland Depth (in) | Squeeze % | Groove Width – Liquids (in) | Groove Width – Gases/Vacuum (in) | Corner Radius (in) |
|---|---|---|---|---|---|---|
| -004 to -050 | 0.070 ± 0.003 | 0.050 – 0.054 | 19 – 32 | 0.101 – 0.107 | 0.084 – 0.089 | 0.005 – 0.015 |
| -102 to -178 | 0.103 ± 0.003 | 0.074 – 0.080 | 20 – 30 | 0.136 – 0.142 | 0.120 – 0.125 | 0.005 – 0.015 |
| -201 to -284 | 0.139 ± 0.004 | 0.101 – 0.107 | 20 – 30 | 0.177 – 0.187 | 0.158 – 0.164 | 0.010 – 0.025 |
| -309 to -395 | 0.210 ± 0.005 | 0.155 – 0.165 | 20 – 28 | 0.270 – 0.290 | 0.240 – 0.260 | 0.015 – 0.030 |
| -425 to -475 | 0.275 ± 0.006 | 0.205 – 0.215 | 20 – 27 | 0.350 – 0.375 | 0.310 – 0.340 | 0.020 – 0.040 |
Static face seals (flange) usually adopt the narrower gas/vacuum groove width when mating surfaces are rigid with zero diametral clearance. Radial static glands use the liquids width when a small extrusion gap exists.
Lower squeeze (typically 8–20 %) reduces friction and wear for moving piston and rod seals.
| CS Series | Cross-Section (in) | Gland Depth (in) | Squeeze % | Groove Width – No Backup (in) | 1 Backup Ring (in) | 2 Backup Rings (in) | Corner Radius (in) |
|---|---|---|---|---|---|---|---|
| -004 to -050 | 0.070 | 0.055 – 0.057 | 15 – 25 | 0.093 – 0.098 | 0.138 – 0.143 | 0.205 – 0.210 | 0.005 – 0.015 |
| -102 to -178 | 0.103 | 0.088 – 0.090 | 10 – 17 | 0.140 – 0.145 | 0.171 – 0.176 | 0.238 – 0.243 | 0.005 – 0.015 |
| -201 to -284 | 0.139 | 0.119 – 0.123 | 9 – 17 | 0.185 – 0.191 | 0.222 – 0.230 | 0.301 – 0.310 | 0.010 – 0.025 |
| -309 to -395 | 0.210 | 0.183 – 0.188 | 8.5 – 15 | 0.280 – 0.288 | 0.338 – 0.350 | 0.428 – 0.440 | 0.015 – 0.030 |
| -425 to -475 | 0.275 | 0.234 – 0.240 | 10 – 17 | 0.365 – 0.375 | 0.440 – 0.460 | 0.579 – 0.600 | 0.020 – 0.040 |
Keep diametral extrusion clearance within pressure-rated limits. Install backup rings when working pressure exceeds roughly 1500 psi or clearance is oversized.
Standard groove dimensions for common metric cross-sections used in cylinder piston/rod glands and flange face seals.
| CS (mm) | Cylinder Depth L (mm) | Cylinder Width G – 0 BR | Cylinder Width – 1 BR | Cylinder Width – 2 BR | Flange Depth L (mm) | Flange Width G (mm) | Radius R (mm) |
|---|---|---|---|---|---|---|---|
| 1.0 | 0.80 | 1.4 | – | – | 0.65 | 1.4 | 0.2 |
| 1.5 | 1.20 | 2.1 | – | – | 1.00 | 2.1 | 0.2 |
| 1.78 | 1.42 | 2.5 | 3.9 | 5.3 | 1.25 | 2.5 | 0.3 |
| 2.0 | 1.60 | 2.5 | 3.9 | 5.3 | 1.40 | 2.5 | 0.3 |
| 2.5 | 2.05 | 3.4 | 4.8 | 6.2 | 1.80 | 3.4 | 0.4 |
| 2.62 | 2.10 | 3.5 | 5.0 | 6.4 | 1.85 | 3.5 | 0.4 |
| 3.0 | 2.40 | 3.9 | 5.3 | 6.7 | 2.20 | 3.9 | 0.5 |
| 3.53 | 2.85 | 4.7 | 6.2 | 7.6 | 2.60 | 4.7 | 0.6 |
| 4.0 | 3.20 | 5.4 | 7.1 | 8.8 | 3.00 | 5.4 | 0.6 |
| 5.0 | 4.00 | 6.7 | 8.4 | 10.1 | 3.80 | 6.7 | 0.8 |
| 5.33 | 4.30 | 7.1 | 9.0 | 10.8 | 4.10 | 7.1 | 0.8 |
| 6.0 | 4.80 | 8.2 | 9.9 | 11.6 | 4.60 | 8.2 | 1.0 |
| 7.0 | 5.60 | 9.5 | 12.0 | 14.5 | 5.40 | 9.5 | 1.2 |
Cylinder columns apply to piston and rod radial glands; flange columns apply to axial face seals. BR = backup ring. Listed radii apply without backup rings; use smaller radii when backup rings are fitted.
Select a standard cross-section and application type to get recommended nominal groove depth, width and squeeze values.
These values are nominal design references. Apply manufacturing tolerances and verify against pressure, temperature and chemical compatibility for your project.
Static grooves use higher squeeze (15–30 %) since there is no relative motion. Reciprocating dynamic grooves use lower squeeze (8–20 %) to cut friction, heat and wear; groove widths are also adjusted to accommodate lubrication and backup rings.
Groove depth ≈ CS × (1 − target squeeze fraction). Example: 0.139 in CS with 15 % squeeze → depth ≈ 0.139 × 0.85 ≈ 0.118 in. Always reference official standard tables for exact toleranced values.
Add the thickness of each backup ring to the standard no-backup groove width. Common backup ring thickness is 0.04–0.06 in (1–1.5 mm); use the dedicated 1-BR / 2-BR columns in the dynamic table for ready-made values.
They are similar for matching cross-sections but not interchangeable. AS568 is inch-based while ISO 3601 is metric; follow the matching standard for your hardware unit system.
Small CS parts use 0.005–0.015 in radii; larger cross-sections use 0.020–0.040 in radii. Smooth rounded corners reduce stress risers and protect the seal during assembly.
1–5 % ID stretch is ideal. Stretch over 8–10 % shrinks the effective cross-section, raises compression set risk and shortens service life; custom gland geometry may be required for oversized stretch cases.
Static surfaces: 32 µin Ra (0.8 µm) or finer. Dynamic sliding surfaces: 16 µin Ra (0.4 µm) or finer. Concentric circular tool marks are preferred over spiral patterns.
Dovetail / half-dovetail grooves are used for face seals needing retention during assembly or vacuum service. They demand higher machining precision and are mostly limited to static applications.