Cast Iron Pipe

Applicable Technologies

Structural Assessment

Visual & Sounding

Leak & Gas Pocket

Acoustic Monitoring

RTPM

Video Inspection

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 Cast iron pipe was gradually superseded by ductile iron pipe, which is a direct development, with most existing manufacturing plants transitioning to the new material during the 1970s and 1980s.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	Disadvantages
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	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 Poor records

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