GB/T 3452.1 O-Ring Size Guide
The Chinese national standard for hydraulic and pneumatic O-rings, dimensionally aligned with the ISO 3601 metric G-series.
GB/T 3452.1-2005 covers O-ring dimension series and tolerances for general (G-series) hydraulic and pneumatic applications in China. Its size table matches the ISO 3601-1 G-series: cross-sections of 1.8, 2.65, 3.55, 5.3 and 7.0 mm combined with preferred inside diameters, designated ID × CS (e.g. 25×3.55).
Because the dimensions align with ISO 3601, a GB/T 3452.1 size normally has a direct international counterpart — useful when sourcing across regions. Tolerances shown below are typical band values; confirm exact values in the current edition before release drawings.
Common GB/T 3452.1 sizes
| Designation | Nominal ID mm | Cross-section mm | Nominal OD mm | ID tol. ±mm | CS tol. ±mm |
|---|---|---|---|---|---|
| 5×1.8 | 5.00 | 1.80 | 8.60 | 0.13 | 0.08 |
| 6.3×1.8 | 6.30 | 1.80 | 9.90 | 0.13 | 0.08 |
| 8×1.8 | 8.00 | 1.80 | 11.60 | 0.13 | 0.08 |
| 10×1.8 | 10.00 | 1.80 | 13.60 | 0.20 | 0.08 |
| 12.5×1.8 | 12.50 | 1.80 | 16.10 | 0.20 | 0.08 |
| 14×1.8 | 14.00 | 1.80 | 17.60 | 0.20 | 0.08 |
| 16×1.8 | 16.00 | 1.80 | 19.60 | 0.20 | 0.08 |
| 18×1.8 | 18.00 | 1.80 | 21.60 | 0.20 | 0.08 |
| 20×1.8 | 20.00 | 1.80 | 23.60 | 0.20 | 0.08 |
| 22.4×1.8 | 22.40 | 1.80 | 26.00 | 0.20 | 0.08 |
| 25×1.8 | 25.00 | 1.80 | 28.60 | 0.30 | 0.08 |
| 28×1.8 | 28.00 | 1.80 | 31.60 | 0.30 | 0.08 |
| 31.5×1.8 | 31.50 | 1.80 | 35.10 | 0.30 | 0.08 |
| 35.5×1.8 | 35.50 | 1.80 | 39.10 | 0.30 | 0.08 |
| 40×1.8 | 40.00 | 1.80 | 43.60 | 0.30 | 0.08 |
| 10.6×2.65 | 10.60 | 2.65 | 15.90 | 0.20 | 0.09 |
| 12.5×2.65 | 12.50 | 2.65 | 17.80 | 0.20 | 0.09 |
| 14×2.65 | 14.00 | 2.65 | 19.30 | 0.20 | 0.09 |
| 16×2.65 | 16.00 | 2.65 | 21.30 | 0.20 | 0.09 |
| 18×2.65 | 18.00 | 2.65 | 23.30 | 0.20 | 0.09 |
| 20×2.65 | 20.00 | 2.65 | 25.30 | 0.20 | 0.09 |
| 22.4×2.65 | 22.40 | 2.65 | 27.70 | 0.20 | 0.09 |
| 25×2.65 | 25.00 | 2.65 | 30.30 | 0.30 | 0.09 |
| 28×2.65 | 28.00 | 2.65 | 33.30 | 0.30 | 0.09 |
| 31.5×2.65 | 31.50 | 2.65 | 36.80 | 0.30 | 0.09 |
| 35.5×2.65 | 35.50 | 2.65 | 40.80 | 0.30 | 0.09 |
| 40×2.65 | 40.00 | 2.65 | 45.30 | 0.30 | 0.09 |
| 45×2.65 | 45.00 | 2.65 | 50.30 | 0.30 | 0.09 |
| 50×2.65 | 50.00 | 2.65 | 55.30 | 0.50 | 0.09 |
| 56×2.65 | 56.00 | 2.65 | 61.30 | 0.50 | 0.09 |
| 60×2.65 | 60.00 | 2.65 | 65.30 | 0.50 | 0.09 |
| 18×3.55 | 18.00 | 3.55 | 25.10 | 0.20 | 0.10 |
| 20×3.55 | 20.00 | 3.55 | 27.10 | 0.20 | 0.10 |
| 22.4×3.55 | 22.40 | 3.55 | 29.50 | 0.20 | 0.10 |
| 25×3.55 | 25.00 | 3.55 | 32.10 | 0.30 | 0.10 |
| 28×3.55 | 28.00 | 3.55 | 35.10 | 0.30 | 0.10 |
| 31.5×3.55 | 31.50 | 3.55 | 38.60 | 0.30 | 0.10 |
| 35.5×3.55 | 35.50 | 3.55 | 42.60 | 0.30 | 0.10 |
| 40×3.55 | 40.00 | 3.55 | 47.10 | 0.30 | 0.10 |
| 45×3.55 | 45.00 | 3.55 | 52.10 | 0.30 | 0.10 |
| 50×3.55 | 50.00 | 3.55 | 57.10 | 0.50 | 0.10 |
| 56×3.55 | 56.00 | 3.55 | 63.10 | 0.50 | 0.10 |
| 63×3.55 | 63.00 | 3.55 | 70.10 | 0.50 | 0.10 |
| 71×3.55 | 71.00 | 3.55 | 78.10 | 0.50 | 0.10 |
| 80×3.55 | 80.00 | 3.55 | 87.10 | 0.50 | 0.10 |
| 40×5.3 | 40.00 | 5.30 | 50.60 | 0.30 | 0.13 |
| 45×5.3 | 45.00 | 5.30 | 55.60 | 0.30 | 0.13 |
| 50×5.3 | 50.00 | 5.30 | 60.60 | 0.50 | 0.13 |
| 56×5.3 | 56.00 | 5.30 | 66.60 | 0.50 | 0.13 |
| 63×5.3 | 63.00 | 5.30 | 73.60 | 0.50 | 0.13 |
| 71×5.3 | 71.00 | 5.30 | 81.60 | 0.50 | 0.13 |
| 80×5.3 | 80.00 | 5.30 | 90.60 | 0.50 | 0.13 |
| 90×5.3 | 90.00 | 5.30 | 100.60 | 0.50 | 0.13 |
| 100×5.3 | 100.00 | 5.30 | 110.60 | 0.90 | 0.13 |
| 125×5.3 | 125.00 | 5.30 | 135.60 | 0.90 | 0.13 |
| 140×5.3 | 140.00 | 5.30 | 150.60 | 0.90 | 0.13 |
| 160×5.3 | 160.00 | 5.30 | 170.60 | 0.90 | 0.13 |
| 180×5.3 | 180.00 | 5.30 | 190.60 | 0.90 | 0.13 |
| 200×5.3 | 200.00 | 5.30 | 210.60 | 1.50 | 0.13 |
| 125×7 | 125.00 | 7.00 | 139.00 | 0.90 | 0.15 |
| 140×7 | 140.00 | 7.00 | 154.00 | 0.90 | 0.15 |
| 160×7 | 160.00 | 7.00 | 174.00 | 0.90 | 0.15 |
| 180×7 | 180.00 | 7.00 | 194.00 | 0.90 | 0.15 |
| 200×7 | 200.00 | 7.00 | 214.00 | 1.50 | 0.15 |
| 224×7 | 224.00 | 7.00 | 238.00 | 1.50 | 0.15 |
| 250×7 | 250.00 | 7.00 | 264.00 | 1.50 | 0.15 |
| 280×7 | 280.00 | 7.00 | 294.00 | 1.50 | 0.15 |
| 315×7 | 315.00 | 7.00 | 329.00 | 1.50 | 0.15 |
| 355×7 | 355.00 | 7.00 | 369.00 | 1.50 | 0.15 |
| 400×7 | 400.00 | 7.00 | 414.00 | 1.50 | 0.15 |
Source & version
GB/T 3452.1-2005《液压气动用O形橡胶密封圈 第1部分：尺寸系列及公差》，与 ISO 3601-1 G 系列尺寸一致。需对照现行版本核实。 · GB/T 3452.1-2005
Standard size data is for preliminary engineering selection only. Final purchasing and design should be verified against the applicable standard edition, supplier data sheets and actual operating conditions.