Tightening torque

The tightening torque is dependent on many factors, in particular however on the friction value in the thread, as well as on the head respectively the nut contact area.

For a medium friction value of μG≈ μK = 0.14 (threads and contact surface is lightly oiled) the tightening torque MA to pre-load FM for the hydraulic torque wrench is indicated.

Considering a divergence of ±10% the assembly torque MA' has been determined for the torque spanner.

Clamping forces and tightening torques for bolts with metric regulation threads DIN 13, for μG≈ μK = 0.14

Strength class to DlN/ISO 898:   8.8   10.9   12.9

Table 4a: Clamping forces and tightening torques for bolts with metric regulation threads DIN 13, for µG ≈ µK = 0.14

Strength class to DIN/ISO 898  8.8
Yield limit Rp 0,2 N/mm²  640 for ≤ M 16
 660 for > M 16
Metric
ISO-
thread 		Cross section
of area
under stress 		Cross section
of thread 		Clamping
force		 For hydr.
and electric
torque wrench 		Ma' = 0.9 MD*
for spanner
DIN 13 AS
mm²		 A3
mm²		 FM
kN		 MA
Nm		 MA'
Nm
M12 84.3 76.2 38.5 87 78
M14 115 105 53 140 126
M16 157 144 72 215 193
M18 193 175 91 300 270
M20 245 225 117 430 387
M22 303 282 146 580 522
M24 353 324 168 740 666
M27 459 427 221 1100 990
M30 561 519 270 1500 1350
M33 694 647 335 determined bolt through
yield measurement
M36 817 759 395
M39 976 913 475
M42 1120 1045 542
M45 1300 1224 635
M48 1470 1377 714
M52 1760 1652 857
M56 2030 1905 989
M60 2360 2227 1156


Tabelle 4b: Clamping forces and tightening torques for bolts with metric regulation threads DIN 13, for µG ≈ µK = 0.14

Strength class to DIN/ISO 898  10.9
Yield limit Rp 0,2 N/mm²  940
Metric
ISO-
thread 		Cross section
of area
under stress 		Cross section
of thread 		Clamping
force		 For hydr.
and electric
torque wrench 		Ma' = 0.9 MD*
for spanner
DIN 13 AS
mm²		 A3
mm²		 FM
kN		 MA
Nm		 MA'
Nm
M12 84.3 76.2 56 130 117
M14 115 105 77 205 184
M16 157 144 106 310 279
M18 193 175 129 430 387
M20 245 225 166 620 558
M22 303 282 208 830 747
M24 353 324 239 1060 954
M27 459 427 315 1550 1395
M30 561 519 385 2100 1890
M33 694 647 480 determined bolt through
yield measurement
M36 817 759 560
M39 976 913 670
M42 1120 1045 772
M45 1300 1224 905
M48 1470 1377 1018
M52 1760 1652 1221
M56 2030 1905 1408
M60 2360 2227 1647


Tabelle 4c: Clamping forces and tightening torques for bolts with metric regulation threads DIN 13, für µG ≈ µK = 0.14

Strength class to DIN/ISO 898  12.9
Yield limit Rp 0,2 N/mm²  1100
Metric
ISO-
thread 		Cross section
of area
under stress 		Cross section
of thread 		Clamping
force		 For hydr.
and electric
torque wrench 		Ma' = 0.9 MD*
for spanner
DIN 13 AS
mm²		 A3
mm²		 FM
kN		 MA
Nm		 MA'
Nm
M12 84.3 76.2 66 150 135
M14 115 105 90 240 216
M16 157 144 124 370 333
M18 193 175 151 510 459
M20 245 225 194 720 648
M22 303 282 243 970 873
M24 353 324 280 1240 1116
M27 459 427 370 1850 1665
M30 561 519 450 2500 2250
M33 694 647 560 determined bolt through
yield measurement
M36 817 759 660
M39 976 913 790
M42 1120 1045 904
M45 1300 1224 1059
M48 1470 1377 1191
M52 1760 1652 1429
M56 2030 1905 1648
M60 2360 2227 1927


* = MA will change with deviating µG or µK