MIL-HDBK-1005/7A
c) Common protective paints, (nonantifouling) with
hard, glossy finishes afford good foundations for fouling
organisms while soft paint finishes do not.
4.7.7.7
Control of Fouling
a) Fine Screening. This method reduces the number of
organisms entering the system; however, most fouling growths
attach themselves at an early growth stage when they are small
enough to pass through fine screens.
b) Chemical Treatment. Chlorination is the most
common treatment used in saltwater handling systems, and is
recommended. Chlorine cannot protect the sections of piping
upstream of the point of application unless back-flushing is
feasible. The method is fairly successful in piping or
circulation systems. It may be relatively expensive to add a
large dosage of chlorine to large volumes of water. This is
often overcome by slug -feeding at high rates about 10 percent of
the time of operation. Copper sulfate may also be useful in
controlling fouling.
c) Antifouling Paints. These paints are in very
common use for protection of exposed material. Almost all
antifouling paints utilize copper because of its toxicity to
waterborne organisms. Antifouling paints must be separated from
a ferrous base metal by a primer coat to prevent interaction
between copper and iron.
d) Velocity Control. Above certain velocities
fouling organisms cannot anchor themselves on piping and/or
pumps. Below the following approximate velocities, fouling will
occur:
PIPE MATERIAL
LIMITING VELOCITY
(approx. fps)
Glass
7
Plastic
8
Steel
11
Cement lining
15
It is not feasible to maintain these velocities in
most sections of a distribution system.
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