Recommended minimum Bolt Torque Values for class 900 spiral wound gaskets Series-A flanges 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
26 20 2-3/4 1814 5443 2459.5 7379.7
28 20 3 2121 6362 2875.7 8625.7
30 20 3 2280 6839 3091.3 9272.4
32 20 3-1/4 2642 7926 3582.1 10746.2
34 20 3-1/2 3010 9030 4081.0 12243.0
36 20 3-1/2 3196 9587 4333.2 12998.2
38 20 3-1/2 3443 10329 4668.1 14004.2
40 24 3-1/2 3041 9123 4123.0 12369.1
42 24 3-1/2 3178 9535 4308.8 12927.7
44 24 3-3/4 3571 10713 4841.6 14524.9
46 24 4 4006 12017 5431.4 16292.9
48 24 4 4163 12488 5644.3 16931.5

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.

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