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Dimensions of Spiral Wound Gaskets ASME B16.20 used with Raised Face flanges ASME B16.47 series A

Spiral Wound Gasket

Other Pressure Classes

150 -
300 -
400 -
600 -
900 -
Class  400  NPS 26-60
NPS Inner Ring Sealing Element Outer Ring
d1 d2 d3 d4
26 660.4 685.8 736.6 891.9
28 711.2 736.6 787.4 892.3
30 755.7 793.8 844.6 946.2
32 812.8 850.9 901.7 1003.3
34 863.6 901.7 952.5 1054.1
36 917.7 955.8 1006.6 1117.6
38 952.5 971.6 1022.4 1073.2
40 1000.3 1025.7 1076.5 1127.3
42 1051.1 1076.5 1127.3 1178.1
44 1104.9 1130.3 1181.1 1231.9
46 1168.4 1193.8 1244.6 1289.1
48 1206.5 1244.6 1295.4 1346.2
50 1257.3 1295.4 1346.2 1403.4
52 1308.1 1346.2 1397 1454.2
54 1352.6 1403.4 1454.2 1517.7
56 1403.4 1454.2 1505 1568.5
58 1454.2 1505 1555.8 1619.3
60 1517.7 1568.5 1619.3 1682.8
NPS Inner Ring Sealing Element Outer Ring
d1 d2 d3 d4
Spiral Wound Gasket

Spiral Wound Gasket

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

Marking of Spiral Wound Gaskets
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