Recommended minimum Bolt Torque Values for class 150 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 150 Bolt Torque
(ft-lb)
Bolt Torque
(N-m)
No. of
Bolts
Bolt
Size
(in)
Min Max Min Max
1/2 4 1/2 11 57 14.9 77.3
3/4 4 1/2 16 57 21.7 77.3
1 4 1/2 22 57 29.8 77.3
1-1/4 4 1/2 24 57 32.5 77.3
1-1/2 4 1/2 33 57 44.7 77.3
2 4 5/8 53 113 71.9 153.2
2-1/2 4 5/8 62 113 84.1 153.2
3 4 5/8 113 113 153.2 153.2
4 8 5/8 66 113 89.5 153.2
5 8 3/4 95 204 128.8 276.6
6 8 3/4 136 204 184.4 276.6
8 8 3/4 204 204 276.6 276.6
10 12 7/8 183 330 248.1 447.4
12 12 7/8 248 330 336.2 447.4
14 12 1 309 496 418.9 672.5
16 16 1 312 496 423.0 672.5
18 16 1-1/8 505 737 684.7 999.2
20 20 1-1/8 445 737 603.3 999.2
24 20 1-1/4 643 1045 871.8 1416.8

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.