AWWA JAW61903

This research analyzed corrosion and corrosion control of ductile- and gray-iron pipe by drawing on a large database of 1,379 pipe specimens and inspections derived from the test programs of the Ductile Iron Pipe Research Association. The study's objectives were twofold: evaluate the accuracy of the 10-point soil evaluation system published in the ANSI/AWWA Standard for Polyethylene Encasement for Ductile-Iron Pipe Systems; and, assess the effectiveness of polyethylene encasement for corrosion control of ductile-iron pipe. Study findings indicated that the 10-point system is an accurate method for evaluating the corrosivity of soils and predicting whether corrosion protection is warranted. In less-aggressive soils, asphaltic ductile-iron pipe did not require additional corrosion protection. Polyethylene encasement controlled corrosion in all soils tested except severe environments and, when properly installed, provided protection beyond the design life of the pipe. Water suppliers can use the 10-point evaluation system to assess the corrosivity of soils where pipe will be buried. For those soils where corrosion control protection is warranted, polyethylene encasement provides an effective, economical, and low-maintenance solution. Includes 15 references, tables, figures.