Wastewater Conveyance - Wastewater Operators - page 177

Maybe application will work. When we normally think of pipe, we
think of any number of possible applications, from conveying raw petro-
leum from field to refinery, to the conveyance of raw water from source
to treatment facility, to wastewater discharge point to treatment to out-
fall, and several others. On the other hand, when we think in terms
of tubing applications and the products conveyed, the conveyance of
compressed air, gases (including liquefied gas), steam, water, lubricating
oil, fuel oil, chemicals, fluids in hydraulic systems, and waste products
comes to mind.

On the surface, it is apparent that when we attempt to classify or dif-
ferentiate piping and tubing, our effort is best characterized as somewhat
arbitrary, capricious, vague, or ambiguous. It appears that piping by any
other name is just piping. In reality, however, piping is not tubing and in
the end (so to speak) the difference may come down to the end use.

4.10.1 Piping vs. Tubing: The difference

Piping and tubing are considered
separate products, even though they are
geometrically quite similar (Lohmeir and
Avery, 2000). Moreover, the classification
of “pipe” or “tube” is determined by end
use. As mentioned, many of the differ-
ences between piping and tubing are related to physical characteristics
and methods of installation, as well as the advantages and disadvan-
tages. Simply, tubing refers to tubular materials (products) made to
either an inside diameter (I.D.) or an outside diameter (O.D.), expressed
in even inches or fractions. Tubing walls are generally much thinner
than those of piping; thus, wall thickness in tubing is of particular
importance. Tubing of different diameters has different wall thick-
nesses; for example, the wall thickness of a commercial type of 8-in.
pipe is 0.406 in. Light-wall 8-in. copper
tubing, by contrast, has a wall thickness
of 0.050 in. When we compare these fig-
ures, it is clear that tubing has much
thinner walls than piping of the same
general diameter (Basavaraju, 2000).

Key Point: It is important to differentiate between
piping and tubing, because they are different.
They are different in physical characteristics and
methods of installation, as well as in their advan-
tages and disadvantages. In this chapter, these
differences will become clear.

Key Point: Wall thickness tolerance in tubing
is held so closely that wall thickness is usually
given in thousandths of an inch rather than as a
larger fraction of an inch. Sometimes the gauge
number indicates the thickness according to a
given system.

Note: The range between thick and thin is narrower for tubing than it is
for piping.

The list of tubing applications is a lengthy one. Some tubing types
can be used not only as conduits for electrical wire but also to convey
waste products, compressed air, hydraulic fluids, gases, fuel oil, chemi-
cals, lubricating oil, steam, waters, and other fluids (i.e., both gaseous
and liquid).

Tubing is made from both metals and plastics. Metal tubing is
designed to be somewhat flexible but also strong. Metallic materials
such as copper, aluminum, steel, and stainless steel are used in applica-
tions where fluids are carried under high pressure; some types of tubing