TYPES AND USES - Continued
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
Torque wrenches are designed to measure the specific
degree of tightness of nuts or bolts. Torque wrenches
are considered precision instruments and therefore must
be calibrated at regular intervals. Torque wrenches are
sometimes 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 facility 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
Change 2 25-11