PIPE SYSTEM HYDRAULICS - Environmentally Conscious Materials Handling - page 243

The summation symbols suggest that multiple minor loss elements and pipe
sections of differing size and/or roughness may exist in a pipe system. It is impor-
tant to use the actual pipe inside diameter and corresponding cross-sectional area
of each pipe section and minor loss element. For a given nominal pipe size, the
inside diameter will vary with pressure class. Pipe head-discharge relationships
are developed by replacing the H L term in equation (5) with equation (12)
4 PIPE SELECTION
Materials commonly used for pressure pipe transporting liquids are ductile iron,
concrete, steel, fiberglass, PVC, and high-density polyethylene (HDPE). National
committees have developed specifications for most types of pipe products. The
specifications discuss external loads, internal design pressure, available sizes,
quality of materials, corrosive environments, installation practices, and linings.
Standards are available from the following organizations:
• American Water Works Association (AWWA)
• American Society of Mechanical Engineers (ASME)
• American Society for Testing and Materials (ASTM)
• American National Standards Institute (ANSI)
• Plastic Pipe Institute (PPI)
• Federal Specifications (FED)
• Canadian Standards Association (CSA)
In addition, manuals and other standards have been published by various man-
ufacturers and manufacturing associations. These specifications and standards
should guide in the selection of pipe material. ASCE (1992) contains a descrip-
tion of most of these pipe materials and a list of the specifications from the
various organizations associated with each material. The document also discusses
the various pipe linings available for corrosion protection. There are several rele-
vant publications for selecting the proper type and pressure class of pipe (ASCE
1992; ASCE 1993; AWWA 1995; AWWA 1989; AWWA 2003; and PPI 1980).
For low-pressure liquid applications, available pipe materials include
un-reinforced concrete; corrugated, spiral-ribbed, and smooth sheet metal;
and HDPE (high-density polyethylene). The choice of a material for a given
application depends on pipe size, pressure requirements, resistance to collapse
from internal vacuum pressures and/or external loads, resistance to internal and
external corrosion, ease of handling and installing, useful life, economics, and
the available driving head versus the friction loss characteristics of the pipe.
When dealing with corrosive liquids or gasses, the corrosion-resistant nature
of the sealing material in the pipe joints must also be taken into consideration.
Most seals are provided by a flat rubber gasket sandwiched between two flanges
or an O-ring that fits inside the bell-end of one pipe and the spigot-end of the