|
The torque or turning effort required to produce a certain stress in bolting is dependent upon a number of conditions, some of which are:
- Diameter of bolt
- Type and number of threads on bolt.
- Material of bolt.
- Condition of nut bearing surfaces.
- 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
|
|
|