252 Fundamentals of Corrosion
cleanup and longer exposure times require a more chemical-resistant coat-
ing system such as system I in Table 7.13.
Other recommendations for this area include systems D, G, and. I in
Table 7.13 and system B in Table 7.16.
7.9.9 area 9: Neutral Chemical Exposure (pH 5.0–10.0)
This is an area that is not subject to direct chemical attack, but may be subject to
fumes, spillage, or splash. Under these conditions, more protection is required
than will be provided by a standard painting system. This would include such
locations as clean rooms, packaging areas, hallways, enclosed process areas,
instrument rooms, electrical load centers, and other similar locations.
A list of potential chemicals that may contact the coating aids in the coat-
ing selection. Knowledge of cleanup procedures will also prove helpful. It
may be possible to use systems requiring less surface preparation, such as
system D in Table 7.13, system A in Table 7.15, system A in Table 7.16, and
system A in Table 7.17.
Recommendations for Area 9 are systems A and D in Table 7.13, system A
in Table 7.15, systems A and C in Table 7.16, and system A in Table 7.17.
7.9.10 area 10: Exposure to Mild Solvents
This is intended for locations subject to intermittent contact with aliphatic
hydrocarbons such as mineral spirits, lower alcohols, glycols, etc. Such con-
tact can be the result of splash, spillage, or fumes.
Crosslinked materials, such as epoxies, are best for this service because
solvents will dissolve single-package coatings. A single coat of inorganic
zinc is an excellent choice for immersion service in solvents or for severe
splashes and spills.
The gloss of a coating system is often reduced as a result of solvent splashes
or spills. However, that is a surface effect that usually does not affect the
overall protective properties of the coating.
Recommended systems for use in this location are A, D, and G in
Table 7.13.
7.9.11 area 11: Extreme pH Exposure
This covers locations that are exposed to strong solvents, extreme pH, oxi-
dizing chemicals, or combinations thereof with high temperatures. The
usual choices for coating these areas are epoxy novalacs, epoxy phenolics,
and high-build polyurethanes. Other special coatings such as the polyesters
and vinyl esters may also be considered. However, these systems require
special application considerations.
Regardless of which coating system is selected, surface preparation is
important. An abrasive blast, even on concrete, is required. In addition, all