text: 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. The lifespan of ductile iron pipe installed in an aggressive environment without appropriate protection may be between 21 and 40 years. The introduction of corrosion mitigation methods for ductile pipe, including the use of polyethylene sleeving, can reduce corrosion by controlling the effect of corrosive soil on piping.
  In the United States, the American National Standards Institute and American Water Works Association have standardized the use of polyethylene sleeving to protect ductile iron pipe from the effects of corrosion. A 2003 report by researchers from the National Research Council of Canada noted that "both good and poor performances" of polyethylene sleeving had been reported. However, a study in the Ductile Iron Pipe Research Association's Florida test site found that, compared with uncoated pipes exposed to a corrosive environment, pipes encased in loose polyethylene sleeving were "in excellent condition".
  Based on a 2005 meta analysis of 1,379 pipe specimens, loose polyethylene sleeving was found to be highly effective at mitigating corrosion. The only environment for which the analysis found the polyethylene sleeving did not provide effective corrosion control was for "uniquely severe" environments, a classification of a rare but extremely corrosive environment. The analysis found that a lifespan of 37 years could be expected in these "uniquely severe" environments.
  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.
  Engineers and water authorities in the United States are divided on the use of different coatings or cathodic protection. Mixed results have been found for all methods of protection. However, this may be due to the impact of variations in local soil corrosiveness and temperature or by damage occurring during installation, which can impact effectiveness of protective coatings.