Table 16-4.--Approximate Torque Required to Obtain
Bolt-Stud Stress of 25,000 psi and 30,000 psi in Various
Sizes of Alloy Steel Bolts and Studs (UNC)
Alloy Steel Bolt
Required to Obtain Required to Obtain
30,000 psi Stress
25,000 psi Stress
Figure 16-22.--Bolt-stud measurements.
has been compressed enough, and it prevents excessive
compression of the gasket and overstressing of the
Bolt-stud stress is checked by measuring the overall
length of the bolt-stud before and after installation to
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
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
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
Figure 16-23.--C-frame gauge for measuring bolt-stud elongation.