Dimensions of Spiral Wound Gaskets of Rating 300# as per ASME B16.20 used with Raised Face flanges ASME B16.5
| Class 300 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 | 54.1 |
| 3/4 | 20.6 | 25.4 | 39.6 | 66.8 |
| 1 | 26.9 | 31.8 | 47.8 | 73.2 |
| 1-1/4 | 38.1 | 47.8 | 60.5 | 82.6 |
| 1-1/2 | 44.5 | 54.1 | 69.9 | 95.3 |
| 2 | 55.6 | 69.9 | 85.9 | 111.3 |
| 2-1/2 | 66.5 | 82.6 | 98.6 | 130.3 |
| 3 | 81.0 | 101.6 | 120.7 | 149.4 |
| 4 | 106.4 | 127.0 | 149.4 | 181.1 |
| 5 | 131.8 | 155.7 | 177.8 | 215.9 |
| 6 | 157.2 | 182.6 | 209.6 | 251.0 |
| 8 | 215.9 | 233.4 | 263.7 | 308.1 |
| 10 | 268.2 | 287.3 | 317.5 | 362.0 |
| 12 | 317.5 | 339.9 | 374.7 | 422.4 |
| 14 | 349.3 | 371.6 | 406.4 | 485.9 |
| 16 | 400.1 | 422.4 | 463.6 | 539.8 |
| 18 | 449.3 | 474.7 | 527.1 | 596.9 |
| 20 | 500.1 | 525.6 | 577.9 | 654.1 |
| 24 | 603.3 | 628.7 | 685.8 | 774.7 |
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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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