Use and Care Guide

7
The pH range for typical DWV systems is between 4.5 and
7. We suggest that the installer establish a uniform slope
for horizontal drainage piping, but not less than permitted
by applicable plumbing code and in compliance with good
plumbing practices, to facilitate flushing of the system.
If operating conditions yield an acidity level of pH 4.3 or
less, we recommend dilution of the waste stream to raise
the pH. If this is not possible, we suggest that the system’s
designer look into a more suitable material.
The National Bureau of Standards and the Cast Iron Pipe
Research Association (now known as the Ductile Iron
Pipe Research Association) have studied the underground
corrosion of cast iron pipe for many years. As a result
of these studies, a procedure has been developed for
determining the need for any special corrosion protection.
This procedure uses a point system to evaluate five soil
characteristics. The procedure and an optional polyethlene
film protection system are provided as an appendix to
ASTM A 74. Additional information is available from
CISPI or Charlotte Pipe.
The corrosion of metals underground is an electrochemical
phenomenon of two main types: galvanic and electrolytic.
Galvanic corrosion is self-generating and occurs on the
surface of a metal exposed to an electrolyte (such as moist,
salt-laden soil). The action is similar to that occurring in a
wet- or dry-cell battery. Differences in electrical potential
between areas on the surface of the metal (pipe) in contact
with such soil may occur for a variety of reasons, including
the joining of different metals (iron and copper or brass).
Potential differences may also be due to the characteristics
of the soil in contact with the pipe surface: e.g. pH, soluble
salt, oxygen and moisture content, temperature and the
presence of certain bacteria. Any one of a combination
of these factors may cause a small amount of electrical
current to flow through the soil between areas on the pipe
or metal surface. Where this current discharges into the
soil from such an area, metal is removed from the pipe
surface and corrosion occurs.
Electrolytic corrosion occurs when direct current from
outside sources enters and the leaves an underground
metal structure such as pipe. At that point where current
leaves the metal surface to return to its source through
the soil, metal is removed and corrosion occurs.
Over 95 percent of the soil in the United States is non-
corrosive to cast iron. Those few soils that are somewhat
corrosive to cast iron include natural soils containing high
concentration of decomposing organic matter (swamps,
peat bogs, etc.), alkalis or salt (tidal) marshes.
Resistance to Abrasion
Cast iron pipe and fittings are highly resistant to abrasion
from sand, gravel, garbage disposal residue, dishwasher
discharge, and debris being carried in suspension along
the lower portion of the sewer or drain.
The Green Choice
A trend toward environmentally sustainable building
practices has grown in recent years. The U.S. government
requires that federal government projects use green
building practices. Many state and local agencies also
offer incentives to encourage the construction of green
buildings.
Charlotte Pipe and Foundry certifies that its cast iron
pipe and fitting products are made from a minimum of
95% recycled content (0% post-industrial material) and
are 100% recyclable. Each year we prevent more than
350 million pounds of scrap iron and steel from entering
overcrowded landfills by converting it into cast iron soil
pipe and fittings. At the end of the life of a building, the
cast iron piping can be recovered and recycled again to
make new cast iron pipe and fittings or other metallic
products.
While plumbing products themselves cannot earn points
toward LEED certification on a project, they do meet
the growing demand by project owners and specifiers to
employ more “green” products.
The choice is clear when your project calls for recycled or
reusable plumbing material; Charlotte Pipe and Foundry.
GENERAL INFORMATION
• NEVER test with or transport/store
compressed air or gas in Cast Iron pipe
or fittings.
• NEVER test Cast Iron pipe or fittings
with compressed air or gas.
• ONLY use Cast Iron pipe and fittings
for drain, waste and vent or sanitary
sewer applications.
Testing with or use of compressed air or gas in Cast Iron
pipe or fittings can result in explosive failures and cause
severe injury or death.