Tightening Torques for Metric Austenitic Stainless Steels (A2 & A4)

Thread Diameter Friction Coefficient Tightening Torque (Nm) Property Class
50 70 80
M1.6

0.1

0.2

0.1

0.1

0.1

0.2

0.2

0.35
M2

0.1

0.2

0.15

0.25

0.2

0.3

0.3

0.4
M2.5

0.1

0.2

0.25

0.45

0.45

0.6

0.6

0.65
M3

0.1

0.2

0.85

1

1

1.1

1.3

1.6
M4

0.1

0.2

0.8

1.3

1.7

2.6

2.3

3.5
M5

0.1

0.2

1.6

2.4

3.4

5.1

4.6

6.9
M6

0.1

0.2

2.8

4.1

5.9

8.8

8

11.8
M8

0.1

0.2

6.8

10.01

14.5

21.4

19.3

28.7
M10

0.1

0.2

13.70

20.30

30

44

39.4

58
M12

0.1

0.2

23.3

34.8

50

74

67

100
M14

0.1

0.2

37.1

56

79

119

106

159
M16

0.1

0.2

56

86

121

183

161

245
M18

0.1

0.2

81

122

174

260

232

346
M20

0.1

0.2

114

173

244

370

325

494
M22

0.1

0.2

154

234

182

279

n/a

n/a
M24

0.1

0.2

197

298

234

355

n/a

n/a
M27

0.1

0.2

275

421

323

502

n/a

n/a
M30

0.1

0.2

374

571

445

680

n/a

n/a
M33

0.1

0.2

506

779

n/a

n/a

n/a

n/a
M36

0.1

0.2

651

998

n/a

n/a

n/a

n/a
M39

0.1

0.2

842

1300

n/a

n/a

n/a

n/a

Stainless Steel Fasteners tend to seize while being assembled (tightened) The risk of seizing is reduced by:

  • Using Fasteners with smooth clean threads (Rolled Threads)
  • Using Molybdenum Disulphide Grease
  • Tightening the screws with low rpm's without interruptions

The tightening torques stated result in a 90% utilization of the yield strength. Conversion factor: Nm to foot pound = 0.7376 Nm to inch pound = 8,851