The potential for corrosion, leading to pipe failure, is significantly impacted by the corrosivity of soil. Unprotected pipes in highly corrosive soil tend to have shorter lifespans
Manufacturers have standardized the use of polyethylene sleeving to protect ductile iron pipe from the effects of corrosion. loose polyethylene sleeving was found to be highly effective at mitigating corrosion. Pipes manufactured under International Organization for Standardization (ISO) standards are typically coated with zinc, to provide protection against corrosion. In instances of more aggressive soils, polyethylene sleeving is installed over the zinc coated pipe to provide added protection.
Cathodic protection may also be used to prevent corrosion and tends to be advocated by corrosion engineers for pipes in corrosive soils as an addition to external dielectric coatings.
Ductile iron pipe is somewhat resistant to internal corrosion in potable water and less aggressive forms of sewage. However, even where pipe material loss and consequently pipe wall reduction is slow, the deposition of corrosion products on the internal pipe wall can reduce the effective internal diameter. A variety of linings are available to reduce or eliminate corrosion, including cement mortar, polyurethane and polyethylene. Of these, cement mortar lining is by far the most common.
