Dimensions of Spiral Wound Gaskets ASME B16.20
used with Raised Face flanges ASME B16.47 series B
OTHER PRESSURE CLASSES
900
| NPS | Inner Ring | Sealing Element | Outer Ring | |
| d1 | d2 | d3 | d4 | |
| 26 | 666.8 | 692.2 | 749.3 | 838.2 |
| 28 | 717.6 | 743 | 800.1 | 901.7 |
| 30 | 781.1 | 806.5 | 857.3 | 958.9 |
| 32 | 838.2 | 863.6 | 914.4 | 1016 |
| 34 | 895.4 | 920.8 | 971.6 | 1073.2 |
| 36 | 920.8 | 946.2 | 997 | 1124 |
| 38 | 1009.7 | 1035.1 | 1085.9 | 1200.2 |
| 40 | 1060.5 | 1098.6 | 1149.4 | 1251 |
| 42 | 1111.3 | 1149.4 | 1200.2 | 1301.8 |
| 44 | 1155.7 | 1206.5 | 1257.3 | 1368.6 |
| 46 | 1219.2 | 1270 | 1320.8 | 1435.1 |
| 48 | 1270 | 1320.8 | 1371.6 | 1485.9 |
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.
- The gasket thickness tolerance is ± 0.13 mm measured across the metallic portion of the gasket, not including the filler, which may protrude slightly beyond the metal.
- The gasket inside diameter tolerance for NPS 26 through NPS 34 is ± 0.8 mm, and the tolerance for NPS 36 through NPS 60 is ± 1.3 mm.
- The gasket outside diameter tolerance for NPS 26 through NPS 60 is ± 1.5 mm.
- The centering ring outside diameter tolerance is ± 0.8 mm.
- The inside diameter tolerance is ± 3.0 mm.
- Thickness of inner and outer ring.. 2.97 mm - 3.33 mm.
- ASME B16.47 Series A flanges NPS 12 through NPS 24 have the same raised face dimensions as ASME B16.5 flanges.
- There are no Class 900 flanges NPS 50 and larger.
Marking of Spiral Wound Gaskets
