MIL-HDBK-1005/16
a)
Ductile Iron Pipe. This type of pipe may be used
in atmospheric exposures but should be protected with an
appropriate coating system (par. 12.3.1). The process used to
produce ductile iron pipe (deLavaud process) creates an external
surface on the pipe that requires special skills to prepare the
surface for coating application. The producers of ductile iron
pipe have these skills and should be used to prepare the surface
and prime ductile iron pipe that requires painting.
b)
Copper Pipe. Only use copper pipe in areas where
are extremely sensitive to exposure to hydrogen sulfide. Because
of the galvanic relationship between copper and ferrous piping,
copper pipe should be dielectrically insulated from ferrous
piping. Use dielectric unions or flanges.
c)
Carbon Steel. Carbon steel may be used in most
applications but requires protection against corrosion. In
underground service, it must be coated with an appropriate system
(par. 12.3.1) for underground applications, which is supplemented
by the application of cathodic protection (par. 12.3.2). This
coating is not necessary if the piping is encased in concrete.
Cathodically protected pipelines should be electrically isolated
from all other structures with dielectric flanges or unions.
Aboveground and immersion applications require an appropriate
coating system (par. 12.3.1). Thermally insulated pipe should be
cleaned and primed before the insulation material is applied.
Using this procedure will minimize the possibility of corrosion
under the insulation, which can exist undetected.
d)
Stainless Steel. Stainless steel is frequently
used in immersion applications, such as for air piping in
aeration basins. Under most environments, Type 304 is adequate.
However, if the chloride levels in the wastewater are several
hundred ppm, then Type 316 stainless steel should be specified.
Stainless steel pipe is appropriate for certain chemical handling
systems (see par. 12.2.6).
e)
Nonmetallic Piping. Piping such as PVC,
chlorinated polyvinylchloride (CPVC), and FRP may be used
successfully in many applications. Thermal plastic materials
(PVC, CPVC) have limited temperature resistance and should be
derated as service temperatures increase above ambient. Thermal-
setting materials (FRP) have higher temperature/pressure ratings.
Both materials have significant coefficients of thermal
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