Environmental Engineering Reference
In-Depth Information
4.9 nonMeTalliC PiPing
Although metal piping is in wide use today, nonmetallic piping
(especially clay and cement) is of equal importance. New processes to
make them more useful in meeting today's needs have modified these
older materials. Relatively speaking, using metallic piping is a new prac-
tice. Originally, all piping was made from clay or wood, and stone soon
followed. Open stone channels or aqueducts were used to transport
water over long distances. After nearly 2000 years of service, some of
these open channels are still in use today.
Common practice today is to use metal piping, although nonmetal-
lic piping is of equal importance and has many applications in water/
wastewater operations. Many of the same materials that have been used
for centuries (clay, for example) are still used today, but now many new
piping materials are available, and the choice depends on the require-
ments of the planned application. The development of new technologi-
cal processes has enabled the modification of older materials for new
applications in modern facilities and has brought about the use of new
materials for old applications, as well. In this section, we discuss non-
metallic piping materials: what they are and where they are most com-
monly used. We also describe how to join sections of nonmetallic piping
and how to maintain them.
4.9.1 nonmetallic Piping Materials
Nonmetallic piping materials used in
wastewater applications include clay, con-
crete, asbestos-cement pipe, and plastic.
Other nonmetallic piping materials include
glass (chemical porcelain pipe) and wood;
for example, continuous-strip wooden pipes
are used to carry water and waste chemicals
in some areas, especially in the western part of the United States. These
materials are not discussed in this text, however, because of their lim-
ited application in wastewater operations.
Key Point:
As with the use of metallic piping,
nonmetallic piping must be used in accor-
dance with the specifications established
and codified by a number of engineering
societies and standards organizations. These
codes were devised to help ensure person-
nel safety and protection of equipment.
4.9.1.1 Clay Pipe
Clay pipes are used to carry or collect indus-
trial wastes, wastewater, and stormwater (they are
not normally used to carry potable water). Clay pipes
typically range in size from 4 to 36 inches in diameter
and are available in more than one grade and strength. Clay pipe is used
in nonpressurized systems. When used in drainpipe applications, for
example, liquid flow is solely dependent on gravity; that is, it is used as
an open channel pipe, whether partially or completely filled. Clay pipe is
manufactured in two forms:
Key Point:
Vitrified clay pipe
is
extremely corrosion proof. It is
ideal for many industrial waste
and wastewater applications.
• Vitriied (glass-like)
• Unglazed (not glassy)
