Bolting Torque Data - Torque Required to Produce Bolt Stress

The torque or turning effort required to produce a certain stress in bolting is dependent upon a number of conditions, some of which are:

  1. Diameter of bolt
  2. Type and number of threads on bolt.
  3. Material of bolt.
  4. Condition of nut bearing surfaces.
  5. Lubrication of bolt threads and nut bearing surfaces.

The tables below reflect the results of many tests to determine the relation between torque and bolt stress. Values are based on steel bolting well lubricated with a heavy graphite and oil mixture. It was found that a non-lubricated bolt has an efficiency of about 50 percent of a well lubricated bolt and also that different lubricants produce results varying between the limits of 50 and 100 percent of the tabulated stress figures.

Data for Use with Machine Bolts and Cold Rolled Steel Stud Bolts Load in Pounds on Bolts and Stud Bolts when Torque Loads Are Applied

Nominal
Diameter
Of Bolt
(Inches)
Number
Of
Threads
Per Inch)
Diameter
At Root
Of Thread
(Inches)
Area
At Root
Of Thread
(Sq. Inch)
7,500 PSI
Torque
Ft. Lbs.
Compres-
sion, Lbs.
15,000 PSI
Torque
Ft. Lbs.
Compres-
sion, Lbs.
30,000 PSI
Torque
Ft. Lbs.
Compres-
sion, Lbs.
1/4
20
0.182
0.027
1
203
2
405
4
810
5/16
18
0.24
0.045
2
338
4
675
8
1350
3/8
16
0.294
0.068
3
510
6
1020
12
2040
7/16
14
0.345
0.093
5
698
10
1395
20
2790
1/2
13
0.4
0.126
8
945
15
1890
30
3780
9/16
12
0.454
0.162
12
1215
23
2430
45
4860
5/8
11
0.507
0.202
15
1515
30
3030
60
6060
3/4
10
0.62
0.302
25
2265
50
4530
100
9060
7/8
9
0.731
0.419
40
3143
80
6285
160
12570
1
8
0.838
0.551
62
4133
123
8265
245
16530
1-1/8
7
0.939
0.693
98
5190
195
10380
390
20760
1-1/4
7
1.064
0.89
137
6675
273
13350
545
26700
1-3/8
6
1.158
1.054
183
7905
365
15810
730
31620
1-1/2
6
1.283
1.294
219
9705
437
19410
875
38820
1-5/8
5-1/2
1.389
1.515
300
11363
600
22725
1200
45450
1-3/4
5
1.49
1.744
390
13080
775
26160
1550
52320
1-7/8
5
1.615
2.049
525
15368
1050
30735
2100
61470
2
4-1/2
1.711
2.3
563
175250
1125
34500
2250
69000

Data For Use with Alloy Steel Stud Bolts Load in Pounds on Stud Bolts when Torque Loads Are Applied

Nominal
Diameter
Of Stud
(Inches)
Number
Of
Threads
Per Inch)
Diameter
At Root
Of Thread
(Inches)
Area
At Root
Of Thread
(Sq. Inch)
30,000 PSI
Torque
Ft. Lbs.
Compres-
sion, Lbs.
STRESS
45,000 PSI
Torque
Ft. Lbs.
Compres-
sion, Lbs.
60,000 PSI
Torque
Ft. Lbs.
Compres-
sion, Lbs.
1/4
20
0.185
0.027
4
810
6
1215
8
1620
5/16
18
0.24
0.045
8
1350
12
2025
16
2700
3/8
16
0.294
0.068
12
2040
18
3060
24
4080
7/16
14
0.345
0.093
20
2790
30
4185
40
5580
1/2
13
0.4
0.126
30
3780
45
5670
60
7560
9/16
12
0.454
0.162
45
4860
68
7290
90
9720
5/8
11
0.507
0.202
60
6060
90
9090
120
12120
3/4
10
0.62
0.302
100
9060
150
13590
200
18120
7/8
9
0.731
0.419
160
12570
240
18855
320
25140
1
8
0.838
0.551
245
16530
368
24795
490
33060
1-1/8
8
0.963
0.728
355
21840
533
32760
710
43680
1-1/4
8
1.088
0.929
500
27870
750
41805
1000
55740
1-3/8
8
1.213
1.155
680
34650
1020
51975
1360
69300
1-1/2
8
1.338
1.405
800
42150
1200
63225
1600
84300
1-5/8
8
1.463
1.68
1100
50400
1650
75600
2200
100800
1-3/4
8
1.588
1.98
1500
59400
2250
89100
3000
118800
1-7/8
8
1.713
2.304
2000
69120
3000
103680
4000
138240
2
8
1.838
2.652
2200
79560
3300
119340
4400
159120
2-1/4
8
2.088
3.423
3180
102690
4770
154035
6360
205380
2-1/2
8
2.338
4.292
4400
128760
6600
193140
8800
257520
2-3/4
8
2.588
5.259
5920
157770
8880
236655
11840
315540
3
8
2.838
6.324
7720
189720
11580
28450
15440
379440