Page 143 - Trenchless Technology Piping Installation and Inspection

Coatings and Linings for Potable W ater Pipe Distributions 109

American Water Works Association approved epoxy materials potable
water use in 1995 (ANSI/NSF 61 Standard). The primary reason for
using this type of lining technique is to overcome the water quality
problems caused by corrosion of iron pipes. Epoxy linings are usually
classified as a nonstructural technique. Epoxy lining is applied to the
interior surface of existing pipes with a smooth surface finish that
helps prevent further corrosion and tuberculation. Epoxy can effec-
tively halt the recurrence of these problems if the existing pipe is
properly cleaned and lining is adequately applied according to speci-
fications and manufacturer’s guidelines. Figure 3.7 presents removing
of epoxy spray head from the pipe. Similar to cement-mortar linings,
epoxy linings require use of a specialized machine and spray head
(see Fig. 3.8a).
Epoxy resin products are composed of two components, base and
hardener. These two components are supplied in different colors.
When mixed, they form a third distinct color. Figure 3.8 (b) shows the
finished epoxy lining. Table 3.6 represents advantages and limita-
tions of epoxy linings.

3.16.3 Polyurea
Polyurea pipe lining is a rapidly growing market due to polyurea’s
ability to solve difficulties other lining methods face, such as the
existing pipe moist or infiltration conditions, and installation speed.

FIGURE 3.7 Epoxy spray head is removed from the pipe. (Source: CuraFlo Inc.)