Dimensions of Spiral Wound Gaskets for Rating 900# as per ASME B16.20 used with Raised Face flanges ASME B16.5
| Class 900 NPS 1/2″ – 24″ | ||||
| NPS | Inner Ring | Sealing Element | Outer Ring | |
| Inside (d1) | Inside (d2) | Outside (d3) | Outside (d4) | |
| Dia. | Dia.mm | Dia.mm | Dia.mm | |
| 1/2 | 14.2 | 19.1 | 31.8 | 63.5 |
| 3/4 | 20.6 | 25.4 | 39.6 | 69.9 |
| 1 | 26.9 | 31.8 | 47.8 | 79.5 |
| 1-1/4 | 33.3 | 39.6 | 60.5 | 88.9 |
| 1-1/2 | 41.4 | 47.8 | 69.9 | 98.6 |
| 2 | 52.3 | 58.7 | 85.9 | 143.0 |
| 2-1/2 | 63.5 | 69.9 | 98.6 | 165.1 |
| 3 | 78.7 | 95.3 | 120.7 | 168.4 |
| 4 | 102.6 | 120.7 | 149.4 | 206.5 |
| 5 | 128.3 | 147.6 | 177.8 | 247.7 |
| 6 | 154.9 | 174.8 | 209.6 | 289.1 |
| 8 | 196.9 | 222.3 | 257.3 | 358.9 |
| 10 | 246.1 | 276.4 | 311.2 | 435.1 |
| 12 | 292.1 | 323.9 | 368.3 | 498.6 |
| 14 | 320.8 | 355.6 | 400.1 | 520.7 |
| 16 | 374.7 | 412.8 | 457.2 | 574.8 |
| 18 | 425.5 | 463.6 | 520.7 | 638.3 |
| 20 | 482.6 | 520.7 | 571.5 | 698.5 |
| 24 | 590.6 | 628.7 | 679.5 | 838.2 |
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General notes:
- Dimensions are in millimeters unless otherwise indicated.
- Image shows a Spiral Wound gasket with Inner – and Outer ring.
- d1 = Inside diameter when Inner ring is used.
- d2 = Inside diameter sealing element when no Inner ring is used.
- d3 = Outside diameter of sealing element.
- d4 = Outside diameter of Outer ring.
- Thickness of inner and outer ring: 2.97 mm – 3.33 mm.
- Thickness sealing element: 4.45 mm.
- Tolerance Outside diameter for NPS 1/2 through NPS 8 is ± 0.8 mm; for NPS 10 trough NPS 24 tolerance is + 1.5 mm – 0.8 mm.
- ASME B16.20 does not covers class 400 flanges up to NPS 3 and class 900 flanges up to NPS 2½.
- There are no class 400 flanges NPS 1/2 thru NPS 3 (use Class 600), class 900 flanges NPS 1/2 thru NPS 2½ (use Class 1500), or class 2500 flanges NPS 14 or larger.
- The inner ring inside diameters shown for NPS 1¼ thru 2½ in class 1500 and 2500 will produce inner ring widths of 0.12 inches, a practical minimum for production purposes.
- ASME B16.20 which covers spiral wound gaskets requires the use of solid metal inner rings in: Pressure Class 900, nominal pipe sizes 24 and larger, Pressure Class 1500 from nominal pipe sizes 12 and larger, Pressure Class 2500 from nominal pipe sizes 4 and larger and all PTFE filled gaskets.
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