Recommended minimum Bolt Torque Values for class 900 spiral wound gaskets with inner ring for Series A flanges.
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 7257 2459.5 9839.2
28 20 3 2121 8482 2875.7 11500.0
30 20 3 2280 9118 3091.3 12362.3
32 20 3-1/4 2642 10568 3582.1 14328.3
34 20 3-1/2 3010 12040 4081.0 16324.0
36 20 3-1/2 3196 12782 4333.2 17330.1
38 20 3-1/2 3443 13772 4668.1 18672.3
40 24 3-1/2 3041 12164 4123.0 16492.2
42 24 3-1/2 3178 12714 4308.8 17237.9
44 24 3-3/4 3571 14284 4841.6 19366.5
46 24 4 4006 16022 5431.4 21722.9
48 24 4 4163 16650 5644.3 22574.4

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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