17 Appendix
17.1 Tightening torques for screws with metric screw threads with and without wedge lock washers
17 Appendix
17.1 Tightening torques for screws with metric screw threads with and without wedge lock
washers
Notice
In the case of galvanised screw plugs and screw plugs made of stainless steel the inner thread and
outer thread have to be greased thorough before mounting in order to prevent threads from seizing.
Notice
The manufacturer recommends tightening screws with wedge lock washers according to the table
three times after another with the same tightening torque.
Tightening torque [Nm]
Screws with head contact surface
Countersunk
screws
Stainless steel screws A2
and A4
Thread
5.6
8.8
10.9
8.8+
Alu*
Property
class 70
Property
class 80
8.8
M 3
0.6
1.5
–
1.2
–
–
1
M 4
1.4
3.0
4.1
2.3
–
–
2
M 5
2.7
6.0
8.0
4.8
3.5
4.7
5
M 6
4.7
10.3
14.0
7.6
6.0
8.0
9
M 8
11.3
25.0
34.0
18.4
16.0
22.0
14
M 10
23.0
47.0
68.0
36.8
32.0
43.0
36
M 12
39.0
84.0
117
64.0
56.0
75.0
60
M 14
62.0
133
186
101
–
–
90
M 16
96.0
204
285
155
135
180
100
M 18
133
284
390
224
–
–
–
M 20
187
3999
558
313
280
370
135
M 24
322
687
960
540
455
605
360
Tab. 30: Tightening torques metric screw thread
*When screwing into aluminium, the tightening torque reduces by 20 % when the screw-in depth is less
than double the thread diameter.
17.2 Tightening torques for screw plugs with thread measured in inches and elastomer
seal
Notice
In the case of galvanised screw plugs and screw plugs made of stainless steel the inner thread and
outer thread have to be greased thorough before mounting in order to prevent threads from seizing.
Tightening torque [Nm]
Thread
Galv stainless steel
G 1/8"
13.0
G 1/4"
30.0
G 3/8"
60.0
G 1/2"
80.0
G 3/4"
120
G 1"
200
G 1 1/4"
400
G 1 1/2"
450
Tab. 31: Tightening torques, thread measured in inches
Operating instructions
OID 06en-GB Edition 2019-11
57
