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Tightening Torque Guide

Tightening Torque Guide for Grade 5 & 8 Hex Cap Screws

This table is based on IFI 5th Edition Technical Data N-12/N-16, using Equation (1) and a torque coefficient, K=0.20 for non plated steel fasteners and K=0.15 for plated fasteners.

These Figures represent an estimate of torque (torque being the measurement of friction, not tension) required to induce given preload (clamp load) in a bolt for non-critical applications only. For critical or special applications where greater control is desired this should be experimentally determined. This applies to washer faced or double chamfered hex nuts (or bolts, if bolt is torqued) having a width across flats of approximately 1.5 times the nominal diameter and having threads free of interference.

Because of the many interrelated variables that directly or indirectly affect friction, such as surface texture, type or coating or finish, lubrication, speed of tightening, human error, etc., it is possible to experience as much as ±25% deviation in preload (clamp load) with the use of a torque wrench.

!!!Attention!!! Our printed catalog contains an incorrect unit for the column of grade 5 plated, both coarse and fine thread. The 1st plated item in both coarse & fine thread should be measured in (in. lbs.) not (ft. lbs.). The remaining items in the column are correctly labeled as (ft. lbs.). This web page table has been corrected.

GRADE 5
GRADE 8
Coarse Thread
Coarse Thread
Size
Clamp Load
Plain (ft. lbs.)
Plated
Size
Clamp Load
Plain (ft. lbs.)
Plated (ft. lbs.)
1/4-20 (.250)
2025
8
76 in lbs.
1/4-20 (.250)
2850
12
9
5/16-18 (.3125)
3338
17
13 ft lbs.
5/16-18 (.3125)
4725
25
18
3/8-16 (.375)
4950
31
23 ft lbs.
3/8-16 (.375)
6975
44
33
7/16-14 (.4375)
6788
50
37 ft lbs.
7/16-14 (.4375)
9600
70
52
1/2-13 (.500)
9075
76
57 ft lbs.
1/2-13 (.500)
12750
106
80
9/16-12 (.5625)
11625
109
82 ft lbs.
9/16-12 (.5625)
16350
153
115
5/8-11 (.625)
14400
150
112 ft lbs.
5/8-11 (.625)
20325
212
159
3/4-10 (.750)
21300
266
200 ft lbs.
3/4-10 (.750)
30075
376
282
7/8-9 (.875)
29475
430
322 ft lbs.
7/8-9 (.875)
41550
606
454
1-8 (1.000)
38625
644
483 ft lbs.
1-8 (1.000)
54525
909
682
1 1/8-7 (1.125)
42375
794
596 ft lbs.
1 1/8-7 (1.125)
68700
1288
966
1 1/4-7 (1.250)
53775
1120
840 ft lbs.
1 1/4-7 (1.250)
87225
1817
1363
1 3/8-6 (1.375)
64125
1470
1102 ft lbs.
1 3/8-6 (1.375)
103950
2382
1787
1 1/2-6 (1.500)
78000
1950
1462 ft lbs.
1 1/2-6 (1.500)
126450
3161
2371
GRADE 5
GRADE 8
Fine Thread
Fine Thread
Size
Clamp Load
Plain (ft. lbs.)
Plated
Size
Clamp Load
Plain (ft. lbs.)
Plated (ft. lbs.)
1/4-28 (.250)
2325
10
87 in lbs.
1/4-28 (.250)
3263
14
10
5/16-24 (.3125)
3675
19
14 ft lbs.
5/16-24 (.3125)
5113
27
20
3/8-24 (.375)
5588
35
26 ft lbs.
3/8-24 (.375)
7875
49
37
7/16-20 (.4375)
7575
55
41 ft lbs.
7/16-20 (.4375)
10650
78
58
1/2-20 (.500)
10200
85
64 ft lbs.
1/2-20 (.500)
14400
120
90
9/16-18 (.5625)
12975
122
91 ft lbs.
9/16-18 (.5625)
18300
172
129
5/8-18 (.625)
16350
170
128 ft lbs.
5/8-18 (.625)
23025
240
180
3/4-16 (.750)
23775
297
223 ft lbs.
3/4-16 (.750)
33600
420
315
7/8-14 (.875)
32475
474
355 ft lbs.
7/8-9 (.875)
45825
668
501
1-12 (1.000)
42300
705
529 ft lbs.
1-12 (1.000)
59700
995
746
1-14 (1.000)
32275
721
541 ft lbs.
1-14 (1.000)
61125
1019
764
1 1/8-12 (1.125)
47475
890
668 ft lbs.
1 1/8-12 (1.125)
77025
1444
1083
1 1/4-12 (1.250)
59550
1241
930 ft lbs.
1 1/4-12 (1.250)
96600
2012
1509
1 3/8-12 (1.375)
72975
1672
1254 ft lbs.
1 3/8-12 (1.375)
118350
2712
2034
1 1/2-12 (1.500)
87750
2194
1645 ft lbs.
1 1/2-17 (1.500)
142275
3557
2668

 

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