During the inspection of Spiral Wound Gasket Dimensions, you should check for

  • Diameter – Inside / Outside
  • Thickness
  • Centering ring dimensions
  • Permissible Variations of Gasket dimensions are covered in
  • ASME B16.20– that covered dimensions for Metallic Gaskets such as Ring-Joint, Spiral-Wound, and Jacketed
spiral wound gasket dimensions

Spiral Wound Gasket Dimensions Tables

Class 150 and Class 300 Spiral Gasket Dimensions

NPS)Classes
150, 300
Class 150Class 300Class 150Class 300
InchmmInside DiameterOutside Diameter
1⁄231.819.119.147.854.1
3⁄439.625.425.457.266.8
147.831.831.866.873.2
1 1⁄460.547.847.876.282.6
1 1⁄269.954.154.185.995.3
285.969.969.9104.9111.3
2 1⁄298.682.682.6124130.3
3120.7101.6101.6136.7149.4
4149.4127127174.8181.1
5177.8155.7155.7196.9215.9
6209.6182.6182.6222.3251
8263.7233.4233.4279.4308.1
10317.5287.3287.3339.9362
12374.7339.9339.9409.7422.4
14406.4371.6371.6450.9485.9
16463.6422.4422.4514.4539.8
18527.1474.7474.7549.4596.9
20577.9525.5525.5606.6654.1
24685.8628.7628.7717.6774.7

Class 400 and Class 600 Spiral Gasket Dimensions

(NPS)Classes
400, 600
Class 400Class 600Class 400Class 600
InchmmInside DiameterOutside Diameter
1⁄231.8.19.1.54.1
3⁄439.6.25.4.66.8
147.8.31.8.73.2
1 1⁄460.5.47.8.82.6
1 1⁄269.9.54.1.95.3
285.9.69.9.111.3
2 1⁄298.6.82.6.130.3
3120.7.101.6.149.4
4149.4120.7120.7177.8193.8
5177.8147.6147.6212.9241.3
6209.6174.8174.8247.7266.7
8263.7225.6225.6304.8320.8
10317.5274.6274.6358.9400.1
12374.7327.2327.2419.1457.2
14406.4362362482.6492.3
16463.6412.8412.8536.7565.2
18527.1469.9469.9593.9612.9
20577.9520.7520.7647.7682.8
24685.8628.7628.7768.4790.7
Piping Courses

Class 900 and Class 1500 Spiral Wound Gasket Dimensions

(NPS)Classes
900, 1500
Class 900Class 1500Class 900Class 1500
InchmmInside DiameterOutside Diameter
1⁄231.8.19.1.63.5
3⁄439.6.25.4.69.9
147.8.31.8.79.5
1 1⁄460.5.39.6.88.9
1 1⁄269.9.47.8.98.6
285.9.58.7.143
2 1⁄298.6.69.9.165.1
3120.795.392.2168.4174.8
4149.4120.7117.6206.5209.6
5177.8147.6143247.7254
6209.6174.8171.5289.1282.7
8263.7222.3215.9358.9352.6
10317.5276.4266.7435.1435.1
12374.7323.9323.9498.6520.7
14406.4355.6362520.7577.9
16463.6412.8406.4574.8641.4
18527.1463.6463.6638.3704.9
20577.9520.7514.4698.5755.7
24685.8628.7616838.2901.7

Class 2500 Spiral Wound Gasket Dimensions

(NPS)Class
2500
Class 2500Class 2500
InchmmInside DiameterOutside Diameter
1⁄231.819.169.9
3⁄439.625.476.2
147.831.885.9
1 1⁄460.539.6104.9
1 1⁄269.947.8117.6
285.958.7146.1
2 1⁄298.669.9168.4
3120.792.2196.9
4149.4117.6235
5177.8143279.4
6209.6171.5317.5
8263.7215.9387.4
10317.5270476.3
12374.7317.5549.4

All dimensions are in millimeters.

Tolerance in the Dimension of the Spiral 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.
  • Outside diameter tolerance for NPS 1⁄2 through NPS 8 is ±0.8 mm; for NPS 10 through NPS 24, +1.5 mm, −0.8 mm.
  • Inside diameter tolerance for NPS 1⁄2 through NPS 8 is ±0.4 mm; for NPS 10 through NPS 24, ±0.8 mm.
  • The centering ring outside diameter tolerance is ±0.8 mm.

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