Recommended minimum Bolt Torque Values for class 900 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 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 | 41 | 13.6 | 55.6 |
| 3/4 | 4 | 3/4 | 16 | 64 | 21.7 | 86.8 |
| 1 | 4 | 7/8 | 22 | 87 | 29.8 | 118.0 |
| 1-1/4 | 4 | 7/8 | 36 | 143 | 48.8 | 193.9 |
| 1-1/2 | 4 | 1 | 48 | 194 | 65.1 | 263.0 |
| 2 | 8 | 7/8 | 70 | 282 | 94.9 | 382.3 |
| 2-1/2 | 8 | 1 | 83 | 330 | 112.5 | 447.4 |
| 3 | 8 | 7/8 | 110 | 330 | 149.1 | 447.4 |
| 4 | 8 | 1-1/8 | 199 | 737 | 269.8 | 999.2 |
| 5 | 8 | 1-1/4 | 281 | 1045 | 381.0 | 1416.8 |
| 6 | 12 | 1-1/8 | 229 | 737 | 310.5 | 999.2 |
| 8 | 12 | 1-3/8 | 352 | 1407 | 477.2 | 1907.6 |
| 10 | 16 | 1-3/8 | 321 | 1283 | 435.2 | 1739.5 |
| 12 | 20 | 1-3/8 | 359 | 1429 | 486.7 | 1937.5 |
| 14 | 20 | 1-1/2 | 425 | 1701 | 576.2 | 2306.2 |
| 16 | 20 | 1-5/8 | 574 | 2295 | 778.2 | 3111.6 |
| 18 | 20 | 1-7/8 | 963 | 3852 | 1305.7 | 5222.6 |
| 20 | 20 | 2 | 1013 | 4053 | 1373.4 | 5495.1 |
| 24 | 20 | 2-1/2 | 1517 | 6067 | 2056.8 | 8225.7 |
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.