Home>Technical Resources for Fasteners>Stainless Steel Fasteners Pre-Load and Tightening Torques
Bolt Nut Fastener

Stainless Steel Fasteners Pre-Load and Tightening Torques

Optimas are a full-service supply chain and manufacturing solutions provider.   Before you design your next product or make updates to an existing product, consider partnering with Optimas to take advantage of our many capabilities.

This table shows the maximum permissible tightening torques and the resulting maximum preload for A1, A2 and A4 stainless steel fasteners.

For guidance only

Thread SizeCoeff FrictionPreload (Kn) Property classTightening Torque (Nm) Property classMin Breaking Torque
A1-50A2-70A4-80A1-50A2-70A4-80A1-50A2-70A4-80
M1.60.10.40.550.550.10.10.20.150.20.24
0.20.30.350.350.10.20.35
0.30.20.30.30.20.250.45
M2.00.10.50.60.60.150.20.30.30.40.48
0.20.40.50.50.250.30.4
0.30.250.360.360.40.40.55
M2.50.10.650.90.90.250.450.60.60.90.96
0.20.40.50.50.450.60.65
0.30.30.30.30.60.750.8
M3.00.10.9110.8511.31.11.61.8
0.20.60.650.6511.11.6
0.30.40.450.451.251.351.85
M4.00.11.082.972.970.81.72.32.73.84.3
0.21.122.42.41.32.63.5
0.30.91.941.941.534.1
M5.00.12.264.854.851.63.44.65.57.88.8
0.21.833.933.932.45.16.9
0.31.493.193.192.86.18
M6.00.13.26.856.852.85.989.31315
0.22.595.545.544.18.811.8
0.32.094.494.494.810.413.9
M8.00.15.8612.612.66.814.519.3233237
0.24.7510.210.210.121.428.7
0.33.858.858.8511.925.533.9
M10.00.19.32202013.73039.4466574
0.27.5816.216.220.34458
0.36.1413.113.1245169
M12.00.113.629.129.123.6506780110130
0.211.123.723.734.874100
0.3919.219.24188117
M14.00.118.7404037.179106210290330
0.215.232.632.656119159
0.312.326.426.466141188
M.16.00.125.7555556121161
0.220.944.944.986183245
0.31736.436.4102218291
M18.00.132.2696981174232
0.226.256.256.2122260346
0.321.145.545.5144380411
M20.00.141.388.688.6114224325
0.233.872.472.4173370494
0.327.458.758.7205439586
M22.00.150107107148318424
0.2418888227488650
0.3347272272582776
M24.00.158142142187400534
0.247101101284608810
0.3398383338724966
M27.00.175275
0.261421
0.350503
M33.00.191374
0.275571
0.361680
M36.00.1114506
0.294779
0.376929
M39.00.1135651
0.2110998
0.3891189
0.1162842
0.21331300
0.31081553

Let Us Help You Find Efficiencies