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:

  • 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

0.185

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

17250

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.

Compression, Lbs.

STRESS 45,000 PSI Torque Ft. Lbs.

Compression, Lbs.

60,000 PSI Torque Ft. Lbs.

Compression, 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

284580

15440

379440