Cast iron (grey cast iron) is a historical type of pipe
manufactured in the 19th and 20th centuries that is used as
pressure pipe for transmission of water and sewage. Cast iron
pipe was gradually superseded by ductile iron pipe, which is a
direct development, with most existing manufacturing plants
transitioning to the new material during the 1970s and 1980s.
Most grey cast iron pipes that are in service were manufactured
by either pit casting or spin casting. The earliest cast iron
pipes were vertically pit-cast grey iron. In the early
nineteenth century, the first pit-cast iron pipes in the U.S.
were imported, but from 1830, local production became more
widely established. Pit-cast iron pipes were manufactured and
installed until the 1940s. There is currently almost no new
manufacture of cast iron pipe.
 
Advantages
●Thicker wall than ductile iron or steel
●Similar rate of corrosion to ductile iron and steel
●Most pipes after 1950 supplied with cement mortar lining or
retrofitted
Disadvantages
●No elastic behavior and lower mechanical strength
●Prone to external and internal corrosion in aggressive
conditions
●Older pipes having caulked joints with little flexibility
●Often no external protection
●Most pipes unlined before 1960
●Manufacturing defects including variations in wall thickness
Main Forms Failure in Cast Iron Pipes
Form of
Failure |
Causes of
Failure |
Indicators
of Failure |
Break
failure |
Internal
pitting and
graphitization corrosion |
Lining
damage, wall loss from internal pitting,
graphitization, leaks, external loads, and pressure
variations |
External
pitting and
graphitization corrosion |
Coating
damage, wall loss from external pits, graphitization
(hard to detect), leaks, external loads, and
pressure variations |
Manufacturing defects |
Cracks in
body or bell |
Structural
Failure |
Movements
from thermal, seismic, external loading |
Joint leaks,
poor bedding, and pipe movements |
Thermal
contraction, poor support leading to movement,
internal pressure |
Circumferential cracks, frost regions, leaks, pipe
movements, and expansive clays |
Internal
pressures, external loadings, thermal stresses |
Longitudinal
cracks, frost regions, and changed internal/external
loads |
Leadite
joints |
Cracking at
bell |
Leaks |
Loss of soil
support and bending failure |
Leak noise,
wet areas, and pressure variations |
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