Approximate

Nominal Size

Approximate

Torque

Torque

(inches) of

(foot-pounds)

(foot-pounds)

Alloy Steel Bolt

Required to Obtain Required to Obtain

or Stud

30,000 psi Stress

25,000 psi Stress

30

1/2

25

5/8

50

60

314

83

100

has been compressed enough, and it prevents excessive

160

718

133

245

1

205

compression of the gasket and overstressing of the

355

1-M

295

bolt-stud.

500

416

1-1/4

Bolt-stud stress is checked by measuring the overall

645

1-3/8

567

length of the bolt-stud before and after installation to

800

1-1/2

667

determine the total amount of stretch (elongation). The

total amount of stretch is then divided by the effective

length of the bolt-stud to determine the stretch per inch

The approximate torque required for bolt-stud

of effective length.

stresses of 25,000 psi and 30,000 psi is shown in table

The effective length of a bolt-stud is generally

16-4.

considered to be the distance from the center of one nut

These figures assume that the threads (UNC) are

to the center of the other nut (fig. 16-22).

well lubricated. Torque wrenches should be used to

Naval shipyards and repair ships are equipped with

apply the initial bolt-stud stress. The dial of the torque

strain gauges for measuring bolt-stud elongation. When

wrench indicates the torque (in foot-pounds) applied.

strain gauges are not available, use the best micrometer

The torque values given in table 16-4 should be applied

calipers available. If you do not have micrometer

to obtain the required stress.

calipers, use a C-frame, such as the one shown in figure

Bolt-stud stress must be checked by measuring the

bolt-stud elongation. This check ensures that the gasket

16-23.

16-21