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BA 9142 en 02/2015
6.13.2 Tightening torques and initial stressing forces
The tightening torques apply to friction coefficients of µ
total
= 0.14.
The friction coefficient µ
total
= 0.14 applies here to lightly oiled steel bolts, black-annealed or phosphatised
and dry, cut counter threads in steel or cast iron. Lubricants which alter the friction coefficient are not
permitted and might overload the screw connection.
Table 8: Initial stressing forces and tightening torques for screw connections of strength classes 8.8;
10.9; 12.9 with a common friction coefficient of μ
total
= 0.14
Nominal
diameter of
the thread
Strength
class of the
bolt
Initial stressing force for screw
connection classes from Table 7
Tightening torque for screw
connection classes from Table 7
C D E C D E
d
mm
F
M
min.
N
M
A
Nm
M10
8.8 18000 11500 7200 44.6 38.4 34.3
10.9 26400 16900 10600 65.4 56.4 50.4
12.9 30900 19800 12400 76.5 66.0 58.9
M12
8.8 26300 16800 10500 76.7 66.1 59.0
10.9 38600 24700 15400 113 97.1 86.6
12.9 45100 28900 18100 132 114 101
M16
8.8 49300 31600 19800 186 160 143
10.9 72500 46400 29000 273 235 210
12.9 85000 54400 34000 320 276 246
M20
8.8 77000 49200 30800 364 313 280
10.9 110000 70400 44000 520 450 400
12.9 129000 82400 51500 609 525 468
M24
8.8 109000 69600 43500 614 530 470
10.9 155000 99200 62000 875 755 675
12.9 181000 116000 72500 1020 880 790
M30
8.8 170000 109000 68000 1210 1040 930
10.9 243000 155000 97000 1720 1480 1330
12.9 284000 182000 114000 2010 1740 1550
M36
8.8 246000 157000 98300 2080 1790 1600
10.9 350000 224000 140000 2960 2550 2280
12.9 409000 262000 164000 3460 2980 2670
M42
8.8 331000 212000 132000 3260 2810 2510
10.9 471000 301000 188000 4640 4000 3750
12.9 551000 352000 220000 5430 4680 4180
M48
8.8 421000 269000 168000 4750 4090 3650
10.9 599000 383000 240000 6760 5820 5200
12.9 700000 448000 280000 7900 6810 6080
M56
8.8 568000 363000 227000 7430 6400 5710
10.9 806000 516000 323000 10500 9090 8120
12.9 944000 604000 378000 12300 10600 9500
M64
8.8 744000 476000 298000 11000 9480 8460
10.9 1060000 676000 423000 15600 13500 12000
12.9 1240000 792000 495000 18300 15800 14100
M72x6
8.8 944000 604000 378000 15500 13400 11900
10.9 1340000 856000 535000 22000 18900 16900
12.9 1570000 1000000 628000 25800 22200 19800
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