MIL-HDBK-1005/7A
4.7.7.3
Plastic Piping . There is no significant corrosion
problem in the use of plastic piping and the pipe is not as
susceptible to fouling as other nontoxic materials. Plastic
pipe should be protected from ultraviolet radiation and properly
supported when installed in exposed locations. When installed
underground backfilling with selected material must be specified
in order to prevent surface gouging. PVC piping for drinking
has become suspect by the EPA (refer to 40 CFR Part 141.50).
4.7.7.4
Copper Based Materials . Copper based materials are
commonly used on ships and other floating structures to overcome
both corrosion and fouling. Costs and the rough use that this
type of pipe will receive at shore installations may preclude
its use in extensive distribution systems and particularly in
large diameter pipes. Copper based materials are susceptible to
corrosion by hydrogen sulfide.
4.7.7.5
Cathodic Protection. Details for cathodic protection
design are given in MIL-HDBK-1004/10, Cathodic Protection. MIL-
HDBK-1004/10 deals with cathodic protection for all buried
metallic structures including water supply lines and storage
tanks. For additional information refer to AWWA Manual M27 -
External Corrosion, Introduction to Chemistry and Control,
latest edition. This type of protection will probably control
corrosion economically at the intake piping and structures, and
in some cases may be feasible to use for protecting transmission
lines. Consideration must be given to the effect on adjacent
buried utilities.
4.7.7.6
Fouling . A fouling problem will exist in all
saltwater handling systems. Fouling organisms may reduce
corrosion by protecting the base material or accelerate it by
breaking up protective coatings or corrosion films. Some
barnacles are capable of penetrating bituminous coatings up to
1/4-in.) thick. An important additional point is that fouling
organisms obtain a more secure hold on hard smooth surfaces than
soft material. For example:
a)
Barnacles adhere strongly to stainless steel.
b) Fouling organisms can be fairly easily removed
from soft rubber.
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