Recommended minimum Bolt Torque Values for class 900 spiral wound gaskets without 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 900 | Bolt Torque (ft-lb) |
Bolt Torque (N-m) |
|||
|---|---|---|---|---|---|---|
| No. of Bolts |
Bolt Size (in) |
Min | Max | Min | Max | |
| 1/2 | 4 | 3/4 | 10 | 30 | 13.6 | 40.7 |
| 3/4 | 4 | 3/4 | 16 | 48 | 21.7 | 65.1 |
| 1 | 4 | 7/8 | 22 | 65 | 29.8 | 88.1 |
| 1-1/4 | 4 | 7/8 | 36 | 107 | 48.8 | 145.1 |
| 1-1/2 | 4 | 1 | 48 | 145 | 65.1 | 196.6 |
| 2 | 8 | 7/8 | 70 | 211 | 94.9 | 286.1 |
| 2-1/2 | 8 | 1 | 83 | 248 | 112.5 | 336.2 |
| 3 | 8 | 7/8 | 110 | 329 | 149.1 | 446.1 |
| 4 | 8 | 1-1/8 | 199 | 597 | 269.8 | 809.4 |
| 5 | 8 | 1-1/4 | 281 | 842 | 381.0 | 1141.6 |
| 6 | 12 | 1-1/8 | 229 | 687 | 310.5 | 931.4 |
| 8 | 12 | 1-3/8 | 352 | 1055 | 477.2 | 1430.4 |
| 10 | 16 | 1-3/8 | 321 | 962 | 435.2 | 1304.3 |
| 12 | 20 | 1-3/8 | 359 | 1078 | 486.7 | 1461.6 |
| 14 | 20 | 1-1/2 | 425 | 1276 | 576.2 | 1730.0 |
| 16 | 20 | 1-5/8 | 574 | 1721 | 778.2 | 2333.4 |
| 18 | 20 | 1-7/8 | 963 | 2889 | 1305.7 | 3917.0 |
| 20 | 20 | 2 | 1013 | 3039 | 1373.4 | 4120.3 |
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.