TM 9-243
TYPES AND USES - Continued
PIPE WRENCHES
There are three basic types of pipe wrenches, the
stillson wrench, the strap wrench, and the chain wrench.
They are all used to connect or break pipe joints or to
turn cylindrical parts.
The stillson pipe wrench has a fixed jaw which is on the
end of the handle and an adjustable jaw at the top of the
wrench. Adjustment is made by turning a knurled
adjusting screw which moves the jaw. Always pull the
pipe fitting towards the fixed jaw. The serrated (grooved)
jaws of the stillson wrench will mar soft pipe.
Strap pipe wrenches have a leather or canvas strap
which is attached to the handle. The strap is looped
around the pipe and back through the handle to grip the
pipe. The strap pipe wrench will not scratch the surface
of the pipe.
Chain pipe wrenches have a section of bicycle-type
chain permanently attached to the handle. The upper
section of the head has teeth which mate with the links of
the chain. The chain is wrapped around the pipe and
pulled over the head section of the wrench to grip the
pipe. Chain pipe wrenches will scratch the surface of the
pipe.
T O R Q U E W R E N C H E S
Torque wrenches are designed to measure the spe-
cific degree of tightness of nuts or bolts. Torque
wrenches are considered precision instruments and
therefore must be calibrated at regular intervals.
Torque wrenches are used for final tightening of nuts
or bolts. Torque wrenches are normally calibrated in
a right-hand direction only. If a unit is required to
perform torquing operations in a left-hand direction,
they must request that the supporting calibration fa-
cility calibrate the torque wrench in both directions.
A dial torque wrench has a head which contains the
drive element and a dial for reading the exact amount of
torque.
Change 1
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