TM 5-814-2/AFM 88-11, Vol. 2
CHAPTER 6
PIPING, VALVES AND APPURTENANCES
The Handbook of Ductile Iron Pipe, Cast Iron Pipe
6-1.
Pipe materials, fittings and joints
published by the Cast Iron Pipe Research Association
a. General.
Factors to be considered in the
(CIPRA) will be used for guidance in designing ductile
selection of pipe materials and piping systems for force
iron force mains.
mains are: -Flow characteristics or friction coefficient.
c. Steel. Steel pipe may be used for force mains
-Life expectancy and history of use.
when lined with cement mortar or bituminous materials
-Resistance to scour and abrasion.
to provide internal protection. A bituminous coating
-Resistance to acids, alkalis, high temperature
must be applied for external protection also. Lined and
or corrosive wastes, and corrosive soils.
coated steel pipe is available in diameters 6-inch
-Ease of handling and installation.
through 144-inch. Galvanized steel pipe will be used for
-Physical strength and pressure ratings.
small diameter force mains and pressure sewers from
-Joint watertightness and ease of installation.
1/4-inch to 4-inch in size. Joints for steel pipe less than
-Availability of pipe in required sizes, strengths,
6-inch will be threaded. Pipe 6-inch in diameter and
etc.
larger will have mechanical, push-on, or flanged joints.
-Availability of fittings, connections and
Threaded and flanged joints will be used only for interior
adapters.
piping. Steel pipe will be installed in accordance with
No pipe manufactured is suitable for all installation
the manufacturer's recommendations, and Manual No.
requirements and conditions.
The pipe materials
M11-Steel Pipe Design and Installation published by the
covered in this paragraph are the ones most often used
American Water Works Association (AWWA).
for force mains carrying sanitary and industrial wastes.
d. Concrete. Concrete pressure pipe will generally
Each type of pipe will be evaluated to determine its
be used where high strength or large diameter force
suitability for the particular design. Where iron or
mains are required. The type of cement used for
concrete pipe are to be considered, special attention will
concrete will be selected in accordance with paragraph
be paid to subsurface and soil conditions.
The
6-5a of TM 5-814-1/AFM 88-11, Vol. 1. Pretensioned
characteristics of the soil in which a pipe is placed affect
reinforced concrete pressure pipe is available in
the rates of corrosion, with the most corrosive soils
diameters 10-inch through 42-inch, prestressed concrete
being those having poor aeration and high values of
pressure pipe in diameters 16-inch through 144-inch,
acidity, electrical conductivity, dissolved salts, and
and reinforced concrete pressure pipe in diameters 24-
moisture content. The relative potential for corrosion
inch through 144-inch. Each type utilizes bell and spigot
may be estimated by evaluating the degree of corrosion
joints with rubber gaskets. The Concrete Pressure Pipe
of existing metallic or concrete pipelines previously
Manual, Manual No. M9 published by the American
buried in the soil. Facility engineer personnel will
Water Works Association (AWWA) will be used for
normally have knowledge of these matters. When this
design of force mains.
information is not available, or is nonconclusive,
e. Asbestos-cement. Force mains constructed of
resistivity tests of the soil will be conducted and results
asbestos-cement (A.C.) pressure pipe are durable and
evaluated as required in TM 5-811-4/AFM 88-11, Vol.
light in weight. However, A.C. pipe is affected by
4. Pipe materials found inappropriate for use will be
corrosive wastes and aggressive soils, and must be
deleted from the project specifications.
provided with plastic linings for protection. The type of
b Ductile iron. Ductile iron (D.I.) pipe is suitable
material required for A.C. pipe will be type II in
for force mains used at pumping stations and
accordance with ASTM C 500. Pipe is available in
wastewater treatment facilities. Special uses include
diameters 4-inch through 42-inch, and will be joined by
river crossings, pipe located in unstable soil, highway
means of couplings utilizing rubber gaskets. Design of
and rail crossings, and piping installed above ground.
A.C. force mains will conform to the manufacturer's
D.I. pipe is susceptible to corrosion from acid wastes
recommendations.
and aggressive soils.
Cement linings, bituminous
f. Plastic. Characteristics which make plastic pipe
coatings or polyethelene linings are usually provided for
highly desirable for force main use include high
interior protections. For extremely corrosive soils, a
corrosion resistance, light weight, and low coefficient of
polyethelene encasement is recommended for external
Disadvantages include the possibility of
protection. Pipe is available in 3-inch through 54-inch
excessive pipe wall deflections when installed
diameters, and with mechanical, push-on or flanged
joints. Flanged joints are restricted to interior piping.
6-1
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