Tightening torques - inch screws in Nm
Screw
diameter
Strength 2
Strength 5
Strength 8
No marks on head
3 marks on head
6 marks on head
Inch
mm
Coarse
thread
Fine thread
Coarse
thread
Fine thread
Coarse
thread
Fine thread
1/4
6.4
5.6
6.3
8.6
9.8
12.2
13.5
5/16
7.9
10.8
12.2
17.6
19.0
24.4
27.1
3/8
9.5
20.3
23.0
31.2
35.2
44.7
50.2
7/16
11.1
33.9
36.6
50.2
55.6
70.5
78.6
1/2
12.7
47.5
54.2
77.3
86.8
108.5
122.0
9/16
14.3
67.8
81.3
108.5
122.0
156.0
176.3
5/8
15.9
95.0
108.5
149.1
169.5
216.0
244.0
3/4
19.1
169.5
189.8
271.1
298.3
380.0
427.0
7/8
22.2
176.3
196.6
433.9
474.5
610.0
678.0
1
25.4
257.6
278.0
650.8
718.6
915.2
1017
1 1/8
28.6
359.3
406.8
813.5
908.4
1302
1458
1 1/4
31.8
508.5
562.7
1139
1261
1844
2034
1 3/8
34.9
664.4
759.3
1491
1695
2414
2753
1 1/2
38.1
881.3
989.8
1966
2237
3128
3620
Inch screws
71
