Environmental Engineering Reference
In-Depth Information
4.12.2.3 Changing Sizes of Lines
For certain applications, it is important to reduce the volume of
fluid flow or to increase flow pressure in a piping or tubing system. To
accomplish this a
reducer
(which reduces a line to a smaller pipe size)
is commonly used.
Note:
Reducing is also sometimes accomplished by means of inserting
a bushing into the fitting.
4.12.2.4 Sealing Lines
Pipe
caps
are used to seal or close off the end of a pipe or tube
(similar to corking a bottle). Usually, caps are used in a part of the sys-
tem that has been dismantled. To seal off openings in fittings,
plugs
are used. Plugs also provide a means of access into the piping or tubing
system, in case the line becomes clogged.
4.12.2.5 Connecting Lines
To connect two lengths of piping or tubing together, a coupling or
union is used. A
coupling
is simply a threaded sleeve. A
union
is a three-
piece device that includes a threaded end, an internally threaded bottom
end, and a ring. A union does not change the direction of flow, close off
the pipe, or provide for a branch line. Unions make it easy to connect
or disconnect pipes without disturbing the position of the pipes. Figure
4.29 is a diagram of a shortened piping system that illustrates how some
fittings are used in a piping system. (Figure 4.29 is only for illustrative
purposes; it is unlikely that such a system with so many fittings would
actually be used.)
4.12.3 Types of Connections
Pipe connections may be screwed, flanged, or welded. Each method
is widely used, and each has its own advantages and disadvantages.
Plug
Gate
valve
Reducing
coupling
Union
Y-fitting
Cross
Te e
Cap
Reducing bushing
45° elbow
90° elbow
figure 4.29 Diagram of a hypothetical shortened piping system.
