United States
                        Environmental Protection
                        Agency
 Office of Water
 Washington, D.C.
EPA 832-F-00-068
September 2000
                        Wastewater
                        Technology  Fact Sheet
                        Pipe  Construction  and  Materials
DESCRIPTION

There are several different pipe materials available
for  wastewater collection systems,  each with a
unique characteristic used in different conditions.
The four different pipe materials described in this
fact sheet are ductile iron, concrete, plastic, and
vitrified clay.

Pipe material  selection considerations include
trench conditions (geologic conditions), corrosion,
temperature,  safety requirements, and cost. Key
pipe characteristics are corrosion resistance (interior
and exterior), the scouring factor, leak tightness,
and the hydraulic characteristics.

Pipe manufacturers follow requirements set by the
American Society of Testing Materials (ASTM) or
American Water Works Association (AWWA) for
specific pipe materials.  Specification standards
cover the manufacture  of  pipes  and specify
parameters such as internal  diameter, loadings
(classes),  and  wall  thickness  (schedule).  The
methods of pipe construction vary greatly with the
pipe materials.

Some new pipe materials and construction methods
use the basic materials  of concrete pipes with
modifications  (i.e.,  coatings).     Other  pipe
manufacturing methods use newly developed resins
which offer improvements in  strength, flexibility,
and resistance to certain chemicals.  Construction
methods may also allow for field modifications to
adapt to unique conditions (i.e., river crossings,
rocky trenches, etc.) or  may allow for special,
custom ordered diameters and lengths.
Ductile Iron Pipe

Ductile iron pipe (DIP) is an outgrowth of the cast
iron pipe industry. Improvements in the metallurgy
of cast iron in the 1940's increased the strength of
cast iron pipe and added ductility, an ability to
slightly deform without cracking. This was a maj or
advantage and ductile iron pipe quickly became the
standard pipe material for high pressure service for
various uses (water, gas, etc.).

Concrete Pipe

Two types  of concrete pipe commonly used today
are prestressed concrete cylinder pipe (PCCP) and
reinforced concrete pipe (RCP).  PCCP is used for
force  mains, while RCP  is  used  primarily  for
gravity lines. PCCP may be of either embedded-
cylinder (EC) or lined-cylinder construction (LC).
The construction process for both the LC and EC
begins by casting a concrete core in a steel cylinder.
This single process produces the LC pipe. Once the
cylinder cures, it is wrapped with a prestressed steel
wire and coated with a cement slurry  and a dense
mortar or concrete coating to produce the EC pipe.
The manufacturing process for reinforced concrete
cylinder pipe (RCCP)  is  similar to  embedded-
cylinder, however, a reinforcing cage and the steel
cylinder are positioned within a reusable vertical
form and the concrete is cast instead of using the
prestressed wire.  RCCP can be cured by using
either water or steam.

Plastic Pipe

Plastic pipe is made from either thermoplastic or
thermoset plastics. Characteristics and construction
vary, but new materials offer high strength and
good rigidity. Fluorocarbon plastics are the most
resistant to attack from acids, alkalies, and organic

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compounds, but  other  plastics  also  have  high
chemical resistance.  Plastic pipe design must
include stiffness, loading , and hydrostatic design
stress requirements for pressure piping.

Thermoplastics are plastic materials which change
shape when they are heated. Common plastics used
in pipe manufacturing include Polyvinyl Chloride
(PVC),  Polyethylene (PE  or HOPE for High-
Density  PE),  Acrylonitrile-butadiene-styrene
(ABS),  and    Polybutylene (PB).   HOPE  is
commonly used with pipe bursting.  PVC is strong,
lightweight, and somewhat flexible. PVC pipe is
the most widely used plastic pipe material. Other
plastic pipes or composites with plastics and other
materials may be more rigid.

Thermoset plastics are rigid after they have been
manufactured  and are not  able  to be  reformed.
Thermoset plastic pipes are composed of epoxy,
polyester,  and  phenolic  resins,  and are usually
reinforced with fiberglass.   Resins may contain
fillers to extend the resin and to provide specific
characteristics to the final material. The glass fibers
may be wound around the pipes spirally, in woven
configurations, or they may be incorporated into the
resin material as short strands. The pipes may be
centrifugally cast.  Stiffness may also be added in
construction   as   external   ribs  or   windings.
Reinforced Plastic Mortar (RPM) and Reinforced
Thermosetting  Resin  (RTR)   (or  Fiberglass
Reinforced Plastic Pipe (FRP)) are the two basic
classes of these pipes. Another name is Fiberglass
Reinforced Polymer Mortar (FRPM).  Thermoset
pipes are  often manufactured  according to the
specific buyer requirements and may include liners
of different composition for specific chemical uses.

For plastic pipes, resins composed of polymerized
molecules are mixed with lubricants, stabilizers,
fillers, and pigments, to produce  mixtures  with
different characteristics. Plastic pipes are generally
produced by extrusion. Plastic pipe may be  used
for sliplining or for rehabilitating existing pipes by
inserting or pulling them through a smaller diameter
pipe.  FIDPE pipes may  also be used for bursting
and upgrading.  The smaller diameter pipe may be
anchored into place with mortar or grout.
Vitrified Clay Pipe

Vitrified clay pipes are composed of crushed and
blended clay that are formed into pipes, then dried
and fired in a succession of temperatures. The final
firing gives the pipes a glassy finish.  Vitrified clay
pipes have been used for hundreds of years and are
strong, resistant to chemical  corrosion, internal
abrasion, and external chemical attack.  They are
also heat resistant. These pipes have an increased
risk of failure when mortar is used in joints because
mortar is more susceptible to chemical attack than
the clay.  Other types of joints are more chemically
stable.   It has been  shown that  the  thermal
expansion of vitrified clay pipes less than many
other types (such as DIP and PVC).

APPLICABILITY

The applicability of different pipe materials varies
with each site and the system requirements.  The
pipe material must be compatible with the soil and
groundwater chemistry.  The  pipe  material also
must  be compatible  with the soil  structure and
topography of  the site,  which  affects the  pipe
location and depth, the supports necessary for the
pipe fill material, and the required strength of the
pipe material. The following list shows background
information to be used in determining what type of
pipe best fits a particular situation:

      Maximum  pressure   conditions  (force
       mains).

       Overburden, dynamic, and static loading.

      Lengths of pipe available.

       Soil conditions, soil chemistry, water table,
       stability.

       Joining materials required.

      Installation equipment required.

       Chemical  and physical properties of the
       wastewater.

       Joint tightness/thrust control.

      Size range requirements.

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  Field and shop fabrication considerations.
  Compatibility with existing systems.
  Manholes, pits, sumps, and other required
  structures to be included.
  Valves (number, size, and cost).
  Corrosion/cathodic protection requirements.
  Maintenance requirements.
      ADVANTAGES AND DISADVANTAGES
      The advantages and disadvantages for specific pipe
      materials are  listed in  Table  1.   The primary
      advantages and disadvantages to consider for pipes
      used in sewer applications include those that are
      related to  construction  requirements,  pressure
      requirements (force  mains),  depth of cover, and
      cost.
    TABLE 1  ADVANTAGES & DISADVANTAGES OF DIFFERENT MATERIALS
Advantages
Disadvantages
Ductile Iron
    Good corrosion resistance when coated
    High strength
Concrete
    Good corrosion resistance
    Widespread availability
    High strength

    Good load supporting capacity
Vitrified Clay
    Very resistant to acids and most chemicals
    Strong


Thermoplastics (PVC, PE, HOPE, ABS)
    Very lightweight
    Easy to install
    Economical
    Good corrosion resistance
    Smooth surface reduces friction losses
    Long pipe sections reduce infiltration
    potential
    Flexible
Thermosets(FRP)
    High strength
    Lightweight
    Corrosion resistant
    Heavy
    Requires careful installation to avoid cracking
    Heavy
    Susceptible to attack by H2S and acids when pipes are
    not coated
    Joints are susceptible to chemical attack
    Brittle (may crack); requires careful installation
    Short length and numerous joints make it prone to
    infiltration and more costly to install

    Susceptible to chemical attack, particularly by solvents
    Strength affected by sunlight unless UV protected
    Requires special bedding
    High material cost
    Brittle (may crack); requires careful installation
    High installation cost
Source: Lamit, 1984, Moser, 1990, Peggs, 1985.

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DESIGN CRITERIA

Design requirements may vary greatly. Pipe design
is  approached differently for both materials and
construction methods.  The mechanics of the soil
that will surround the pipes is a fundamental design
aspect for the support characteristics, especially for
flexible pipes.   The soil type, density,  and  the
moisture content are important characteristics.

COSTS

Costs for piping comparisons  should include both
the costs of the materials as well as the construction
costs. The pipe cost is usually given in dollars per
unit length, traditionally in  $/linear foot, plus the
costs  of the  fittings,  connections,  and  joints.
Construction costs will depend on the  type  of
digging  necessary,   special  field   equipment
requirements,  and  an allowance for  in-field
adjustments to the system. Access to pipe systems
will  also be  a relevant cost  factor,  as  manhole
spacing is dependant on pipe size.

Sanitary sewer construction costs depend on several
variables, including depth, type of soil, presence of
rock, type of bedding material, location (rural vs.
urban areas) clearing costs, and other factors.

Typical pipe materials for small diameter sanitary
sewers (8" through 24" diameter) include  PVC,
vitrified clay,  and ductile iron.  Typical  average
costs  for  sanitary  sewers  (excluding  service
connections and manholes) are provided in Table 2.

The cost per linear foot in the table is based on an
average trench depth of eight feet and excludes
service connections and manholes.  The following
is not included in the cost per linear foot:

1.      Asphalt and gravel driveway repair.

2.      Open cut of roads.

3.      Boring and jacking.

4.      Concrete encasement of pipe  at stream
       crossings or other locations.

5.      Erosion control.

6.      Relocation of other utilities.

Soil material is assumed to be silt, clay, or other
soil mixtures with no requirement for shoring, rock
removal, or dewatering.

REFERENCES

Other Related Fact Sheets

Other  EPA Fact  Sheets  can be  found at  the
following web address:
http://www.epa.gov/owmitnet/mtbfact.htm

1.      Cast Iron Pipe Research Association,  1978.
       Handbook.  5th Edition.

2.      Ductile  Iron  Pipe Research  Association
       (DIPRA), no date.  "Ductile Iron Pipe."
       Internet     site      at
       ktt]3:/Aj/w^^                  accessed
       March 2000.
              TABLE 2  AVERAGE COST/LINEAR FOOT BY PIPE DIAMETER
Pipe Material
VCP
DIP
RCP
PVC
PE
FRP
ABS
2"
-
-
-
$15
-
$21
$11
4"
-
-
-
$19
$7
$30
-
6"
$25
-
-
$23
$12
$42
-
8"
$30
$38
-
$25
$14
$60
-
12"
$38
$50
$11
$30
$9*
-
-
15"
$50
N/A
$17
$38
-
-
-
18"
$65
$75
$23
$50
$16*
-
-
24"
$110
$110
$31
$75
-
-
-
 * Corrugated
 Source: RS Means Heavy Construction Guide (1998).

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3.     Lamit, L.G., 1984. Pipe Fitting and Piping
      Handbook. Prentice-Hall, Inc.

4.     Moser, A.P., 1990. Buried Pipe Design.
      McGraw-Hill, Inc..

5.     Peggs, L.A.,  1985.  Underground Piping
      Handbook.  Robert E. Krieger Publishing
      Company.

6.     U.S.  EPA,  October  1991.   Alternative
      Wastewater  Collection  Systems.
      EPA/625/1-91/024.
7.     WEF,  1986.  Alternative Sewer Systems.
      MOP#FD12.

ADDITIONAL INFORMATION

American Concrete Pipe Association
Josh Beakley, Director of Technical  Services
222 West Las Colinas Boulevard, Suite 641
Irving, Texas 75039-5423

Ductile Iron Pipe Research Association
L. Gregg Horn, P.E.
245 Riverchase Parkway East, Suite O
Birmingham, Alabama 35244

National Clay Pipe Institute
Edward Sikora
P.O. Box 759
Lake Geneva, Wisconsin 53147

University of Houston,
Mohan Neelam
Dept.  of Civil and Environmental Engineering
Houston, Texas 77204-4791

David Venhuizen, P.E.
5803 Gateshead Drive
Austin, TX 78745
The  mention  of  trade  names  or  commercial
products  does  not  constitute  endorsement or
recommendations  for use by the United States
Environmental Protection Agency (EPA).
For more information contact:

Municipal Technology Branch
U.S. EPA
Mail Code 4204
1200 Pennsylvania Avenue, NW
Washington, D.C. 20460
                                                          MTB
                                                         Excellence fri compliance through optimal technical solutions
                                                         MUNICIPAL TECHNOLOGY BRANCH

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