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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 150 Class 300 Class 150 Class 300
Inch mm Inside Diameter Outside Diameter
1⁄2 31.8 19.1 19.1 47.8 54.1
3⁄4 39.6 25.4 25.4 57.2 66.8
1 47.8 31.8 31.8 66.8 73.2
1 1⁄4 60.5 47.8 47.8 76.2 82.6
1 1⁄2 69.9 54.1 54.1 85.9 95.3
2 85.9 69.9 69.9 104.9 111.3
2 1⁄2 98.6 82.6 82.6 124 130.3
3 120.7 101.6 101.6 136.7 149.4
4 149.4 127 127 174.8 181.1
5 177.8 155.7 155.7 196.9 215.9
6 209.6 182.6 182.6 222.3 251
8 263.7 233.4 233.4 279.4 308.1
10 317.5 287.3 287.3 339.9 362
12 374.7 339.9 339.9 409.7 422.4
14 406.4 371.6 371.6 450.9 485.9
16 463.6 422.4 422.4 514.4 539.8
18 527.1 474.7 474.7 549.4 596.9
20 577.9 525.5 525.5 606.6 654.1
24 685.8 628.7 628.7 717.6 774.7

Class 400 and Class 600 Spiral Gasket Dimensions

(NPS) Classes
400, 600		 Class 400 Class 600 Class 400 Class 600
Inch mm Inside Diameter Outside Diameter
1⁄2 31.8 . 19.1 . 54.1
3⁄4 39.6 . 25.4 . 66.8
1 47.8 . 31.8 . 73.2
1 1⁄4 60.5 . 47.8 . 82.6
1 1⁄2 69.9 . 54.1 . 95.3
2 85.9 . 69.9 . 111.3
2 1⁄2 98.6 . 82.6 . 130.3
3 120.7 . 101.6 . 149.4
4 149.4 120.7 120.7 177.8 193.8
5 177.8 147.6 147.6 212.9 241.3
6 209.6 174.8 174.8 247.7 266.7
8 263.7 225.6 225.6 304.8 320.8
10 317.5 274.6 274.6 358.9 400.1
12 374.7 327.2 327.2 419.1 457.2
14 406.4 362 362 482.6 492.3
16 463.6 412.8 412.8 536.7 565.2
18 527.1 469.9 469.9 593.9 612.9
20 577.9 520.7 520.7 647.7 682.8
24 685.8 628.7 628.7 768.4 790.7
Piping Courses

Class 900 and Class 1500 Spiral Wound Gasket Dimensions

(NPS) Classes
900, 1500		 Class 900 Class 1500 Class 900 Class 1500
Inch mm Inside Diameter Outside Diameter
1⁄2 31.8 . 19.1 . 63.5
3⁄4 39.6 . 25.4 . 69.9
1 47.8 . 31.8 . 79.5
1 1⁄4 60.5 . 39.6 . 88.9
1 1⁄2 69.9 . 47.8 . 98.6
2 85.9 . 58.7 . 143
2 1⁄2 98.6 . 69.9 . 165.1
3 120.7 95.3 92.2 168.4 174.8
4 149.4 120.7 117.6 206.5 209.6
5 177.8 147.6 143 247.7 254
6 209.6 174.8 171.5 289.1 282.7
8 263.7 222.3 215.9 358.9 352.6
10 317.5 276.4 266.7 435.1 435.1
12 374.7 323.9 323.9 498.6 520.7
14 406.4 355.6 362 520.7 577.9
16 463.6 412.8 406.4 574.8 641.4
18 527.1 463.6 463.6 638.3 704.9
20 577.9 520.7 514.4 698.5 755.7
24 685.8 628.7 616 838.2 901.7

Class 2500 Spiral Wound Gasket Dimensions

(NPS) Class
2500		 Class 2500 Class 2500
Inch mm Inside Diameter Outside Diameter
1⁄2 31.8 19.1 69.9
3⁄4 39.6 25.4 76.2
1 47.8 31.8 85.9
1 1⁄4 60.5 39.6 104.9
1 1⁄2 69.9 47.8 117.6
2 85.9 58.7 146.1
2 1⁄2 98.6 69.9 168.4
3 120.7 92.2 196.9
4 149.4 117.6 235
5 177.8 143 279.4
6 209.6 171.5 317.5
8 263.7 215.9 387.4
10 317.5 270 476.3
12 374.7 317.5 549.4

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.