ASME B16.20 Spiral Wound Gasket Dimensions
Dimensions of ASME B16.20 spiral wound gaskets for ASME B16.5 flanges in millimetres: inside and outside diameter of the sealing element (winding) and outside diameter of the centering ring, by flange class.
The centering ring locates the gasket inside the bolt circle; the sealing element sits on the raised face. Teshi Group stocks and supplies spiral wound gaskets, normally as a kit with Teshi-manufactured flanges and stud bolts.
ASME B16.20 Spiral Wound Gasket dimensions — tables
Sealing element inside diameter (mm)
| NPSin | DN | Class 150 | Class 300 | Class 600 | Class 900 | Class 1500 | Class 2500 |
|---|---|---|---|---|---|---|---|
| ½" | 15 | 19.1 | 19.1 | 19.1 | 19.1 | 19.1 | 19.1 |
| ¾" | 20 | 25.4 | 25.4 | 25.4 | 25.4 | 25.4 | 25.4 |
| 1" | 25 | 31.8 | 31.8 | 31.8 | 31.8 | 31.8 | 31.8 |
| 1¼" | 32 | 47.8 | 47.8 | 47.8 | 39.6 | 39.6 | 39.6 |
| 1½" | 40 | 54.1 | 54.1 | 54.1 | 47.8 | 47.8 | 47.8 |
| 2" | 50 | 69.9 | 69.9 | 69.9 | 58.7 | 58.7 | 58.7 |
| 2½" | 65 | 82.6 | 82.6 | 82.6 | 69.9 | 69.9 | 69.9 |
| 3" | 80 | 101.6 | 101.6 | 101.6 | 95.3 | 92.2 | 92.2 |
| 4" | 100 | 127.0 | 127.0 | 120.7 | 120.7 | 117.6 | 117.6 |
| 5" | 125 | 155.7 | 155.7 | 147.6 | 147.6 | 143.0 | 143.0 |
| 6" | 150 | 182.6 | 182.6 | 174.8 | 174.8 | 171.5 | 171.5 |
| 8" | 200 | 233.4 | 233.4 | 225.6 | 222.3 | 215.9 | 215.9 |
| 10" | 250 | 287.3 | 287.3 | 274.6 | 276.4 | 266.7 | 270.0 |
| 12" | 300 | 339.9 | 339.9 | 327.2 | 323.9 | 323.9 | 317.5 |
| 14" | 350 | 371.6 | 371.6 | 362.0 | 355.6 | 362.0 | — |
| 16" | 400 | 422.4 | 422.4 | 412.8 | 412.8 | 406.4 | — |
| 18" | 450 | 474.7 | 474.7 | 469.9 | 463.6 | 463.6 | — |
| 20" | 500 | 525.5 | 525.5 | 520.7 | 520.7 | 514.4 | — |
| 24" | 600 | 628.7 | 628.7 | 628.7 | 628.7 | 616.0 | — |
Sealing element outside diameter (mm)
| NPSin | DN | Class 150–600 | Class 900–2500 |
|---|---|---|---|
| ½" | 15 | 31.8 | 31.8 |
| ¾" | 20 | 39.6 | 39.6 |
| 1" | 25 | 47.8 | 47.8 |
| 1¼" | 32 | 60.5 | 60.5 |
| 1½" | 40 | 69.9 | 69.9 |
| 2" | 50 | 85.9 | 85.9 |
| 2½" | 65 | 98.6 | 98.6 |
| 3" | 80 | 120.7 | 120.7 |
| 4" | 100 | 149.4 | 149.4 |
| 5" | 125 | 177.8 | 177.8 |
| 6" | 150 | 209.6 | 209.6 |
| 8" | 200 | 263.7 | 257.3 |
| 10" | 250 | 317.5 | 311.2 |
| 12" | 300 | 374.7 | 368.3 |
| 14" | 350 | 406.4 | 400.1 |
| 16" | 400 | 463.6 | 457.2 |
| 18" | 450 | 527.1 | 520.7 |
| 20" | 500 | 577.9 | 571.5 |
| 24" | 600 | 685.8 | 679.5 |
Centering ring outside diameter (mm)
| NPSin | DN | Class 150 | Class 300 | Class 600 | Class 900 | Class 1500 | Class 2500 |
|---|---|---|---|---|---|---|---|
| ½" | 15 | 47.8 | 54.1 | 54.1 | 63.5 | 63.5 | 69.9 |
| ¾" | 20 | 57.2 | 66.8 | 66.8 | 69.9 | 69.9 | 76.2 |
| 1" | 25 | 66.8 | 73.2 | 73.2 | 79.5 | 79.5 | 85.9 |
| 1¼" | 32 | 76.2 | 82.6 | 82.6 | 88.9 | 88.9 | 104.9 |
| 1½" | 40 | 85.9 | 95.3 | 95.3 | 98.6 | 98.6 | 117.6 |
| 2" | 50 | 104.9 | 111.3 | 111.3 | 143.0 | 143.0 | 146.1 |
| 2½" | 65 | 124.0 | 130.3 | 130.3 | 165.1 | 165.1 | 168.4 |
| 3" | 80 | 136.7 | 149.4 | 149.4 | 168.4 | 174.8 | 196.9 |
| 4" | 100 | 174.8 | 181.1 | 193.8 | 206.5 | 209.6 | 235.0 |
| 5" | 125 | 196.9 | 215.9 | 241.3 | 247.7 | 254.0 | 279.4 |
| 6" | 150 | 222.3 | 251.0 | 266.7 | 289.1 | 282.7 | 317.5 |
| 8" | 200 | 279.4 | 308.1 | 320.8 | 358.9 | 352.6 | 387.4 |
| 10" | 250 | 339.9 | 362.0 | 400.1 | 435.1 | 435.1 | 476.3 |
| 12" | 300 | 409.7 | 422.4 | 457.2 | 498.6 | 520.7 | 549.4 |
| 14" | 350 | 450.9 | 485.9 | 492.3 | 520.7 | 577.9 | — |
| 16" | 400 | 514.4 | 539.8 | 565.2 | 574.8 | 641.4 | — |
| 18" | 450 | 549.4 | 596.9 | 612.9 | 638.3 | 704.9 | — |
| 20" | 500 | 606.6 | 654.1 | 682.8 | 698.5 | 755.7 | — |
| 24" | 600 | 717.6 | 774.7 | 790.7 | 838.2 | 901.7 | — |
Notes
- Dimensions are in millimetres unless stated otherwise.
- For Class 900, NPS ½" to 2½", the Class 1500 gasket is used.
- Class 2500 is listed to NPS 12" only.
- Inner ring inside diameters have been revised between editions of ASME B16.20 and are not tabulated here; ask for the value to the edition your project specifies.
- Nominal sealing element thickness is 4.5 mm (0.175").
Reference information compiled from the published standard for convenience. It does not replace the current edition of the governing standard, which takes precedence. Verify critical dimensions and properties before design, purchase or fabrication. Teshi Engineers & Sales Promoters (P) Ltd accepts no liability for errors or omissions.
Equivalent and related standards to ASME B16.20 Spiral Wound Gasket Dimensions
All equivalents| Region | Standard | Relationship |
|---|---|---|
| Europe | EN 1514-1 / -2 / -4 / EN 12560 | Gaskets for PN and Class flanges |
| China | GB/T 4622.2 / HG/T 20610 / HG/T 20631 | Spiral-wound gaskets for PN and Class flanges |
| China | HG/T 20612 / HG/T 20633 | Ring joint and metal gaskets |
| Japan | JIS B2404 | Gasket dimensions for JIS flanges |
Teshi Group manufactures flanges and fittings to all of these standards on request, including Chinese GB / HG / SH and European EN dimensions for export projects. Always confirm bolting, facing and thickness when substituting one standard for another.
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ASME B16.20 Spiral Wound Gasket Dimensions — size by size
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FAQ
ASME B16.20 spiral wound gasket dimensions: common questions
When is an inner ring required on a spiral wound gasket?
ASME B16.20 requires inner rings for PTFE-filled gaskets, for flexible-graphite-filled gaskets unless the purchaser specifies otherwise, and for larger sizes in the higher classes. The inner ring prevents inward buckling of the winding.
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