shoulder, and a ring with an inside flange at one end
on both sides of the metal while the bolt is secured
and inside threads similar to that on the exterior of
in the structure.
the thread end on the other. A gasket is placed
STUFFING TUBE--A packed tube that makes a
between the thread and bottom ends, which are then
watertight fitting for a cable or small pipe passing
drawn together by the ring. The use of unions
through a bulkhead.
permits connections with a minimum disturbance
SWEATED-- A surface coated with soft solder or tin.
of pipe positions.
In making a sweated joint, the pipe and the fitting
VALVE--A device for regulating, stopping, or starting
are sweated separately and then sweated again after
flow in a system, and for controlling the direction
they have been assembled.
SWIVEL JOINT--A joint that rotates about an axis
VALVE SEAT--A flat or conical fixed surface on
without any loss in its efficiency.
which a valve rests, or against which it presses.
SYSTEM--A grouping of components or equipment
VALVE STEM--A rod or spindle attached to a valve
joined to serve a common purpose.
and used to move the valve.
TAP--A tool used to cut internal threads. Small sizes
are usually solid, but larger sizes are often made
VENT--A valve or pipe in a tank or compartment used
with inserted cutters so that they may be withdrawn
to permit air to escape.
from the work, without stopping, when the desired
WARPING--The distortion, twisting, or bending of
threads have been cut.
metal from its normal form caused by the
TEE--A fitting with a side outlet at right angles to the
absorption and loss of heat.
run; a single outlet branch pipe.
WATER HAMMER--A shock or blow on metal
TEE BAR--A rolled or extruded structural shape
piping that results when flow is suddenly arrested.
having a cross section shaped like the letter T.
An example is steam condensing into water and
rushed against elbows, or valves, by the force of
TEMPERING--The heating and controlled cooling of
following steam rushing into cold and partially
a metal to produce the desired hardness.
empty pipe. The remedy is easy bends in pipe, slow
TEMPLATE-- A piece of thin material used as a
admission of fluid until all piping in the system is
true-scale guide or as a model to reproduce various
brought to the required temperature, and slow
closure of valves.
TOE--The edge of a flange on a bar.
WELDED FLANGE JOINT--A joint made by
TRIANGULATION-- A technique used to develop
flanges attached to a pipe by welding. The
complex sheet metal forms by using geometrical
material of the flange must be capable of being
constructions to translate dimensions from the
welded. The end of the pipe is slipped through
drawing to the pattern.
the flange ring forgings, and then the assembly is
UNDERCUT-- A defect in the toe of a weld bead
brought to welding heat and hammered or pressed
where the base metal is washed away by the
welding process, leaving a crater.
WELDING LEAD--The conductor through
UNITED STATES STANDARD THREAD--The
which electrical current is transmitted from the
standard screw thread with an inclined angle of
power source to the electrode holder and
60 degrees between threads and one-eighth
flattened at top and bottom. It is also known as
WHEEL VALVE--A stop or gate valve that can be
Sellers Thread and Franklin Institute Standard
opened by means of a handwheel and screw rather
than by the lever, which is a feature of some gate
UNION--A term used to describe almost any device
valves, and of some butterfly and other throttle
used to connect pipes. A union ordinarily
consists of three pieces: thread end fitted with
WIRE-- The term applied to pipefitting means a
exterior and exterior threads, bottom end fitted
template that has been bent for a piece of pipe.
with interior threads and a small exterior