Recommended minimum Bolt Torque Values for class 400 spiral wound gaskets with inner ring.
Bolt Torque values are specified in ft-lb and N-m.
Bolt torques are based on design bolt stress of 60 ksi and a nut factor (K factor) of 0.18.
| NPS (in) |
Class 400 | Bolt Torque (ft-lb) |
Bolt Torque (N-m) |
|||
|---|---|---|---|---|---|---|
| No. of Bolts |
Bolt Size (in) |
Min | Max | Min | Max | |
| 1/2 | 4 | 1/2 | 10 | 41 | 13.6 | 55.6 |
| 3/4 | 4 | 5/8 | 16 | 64 | 21.7 | 86.8 |
| 1 | 4 | 5/8 | 22 | 87 | 29.8 | 118.0 |
| 1-1/4 | 4 | 5/8 | 27 | 110 | 36.6 | 149.1 |
| 1-1/2 | 4 | 3/4 | 39 | 156 | 52.9 | 211.5 |
| 2 | 8 | 5/8 | 50 | 199 | 67.8 | 269.8 |
| 2-1/2 | 8 | 3/4 | 58 | 232 | 78.6 | 314.5 |
| 3 | 8 | 3/4 | 85 | 330 | 115.2 | 447.4 |
| 4 | 8 | 7/8 | 155 | 330 | 210.2 | 447.4 |
| 5 | 8 | 7/8 | 196 | 330 | 265.7 | 447.4 |
| 6 | 12 | 7/8 | 178 | 330 | 241.3 | 447.4 |
| 8 | 12 | 1 | 284 | 496 | 385.1 | 672.5 |
| 10 | 16 | 1-1/8 | 314 | 737 | 425.7 | 999.2 |
| 12 | 16 | 1-1/4 | 476 | 1045 | 645.4 | 1416.8 |
| 14 | 20 | 1-1/4 | 390 | 1045 | 528.8 | 1416.8 |
| 16 | 20 | 1-3/8 | 559 | 1429 | 757.9 | 1937.5 |
| 18 | 24 | 1-3/8 | 596 | 1429 | 808.1 | 1937.5 |
| 20 | 24 | 1-1/2 | 717 | 1897 | 972.1 | 2572.0 |
| 24 | 24 | 1-3/4 | 1000 | 3117 | 1355.8 | 2572.0 |
1] For typical calculation of bolt torque values refer to article: Calculation of Bolt Torque for Flanged Joint Assembly.
2] Bolt Torque values provided in table above are for guidance only. For actual applied torque values follow gasket vendor recommendations.