Ductile iron, pipeline

It should be noted that it is extremely difficult to predict service lives of buried pipelines from the results of controlled trials with small specimens, whether in the laboratory or in the field. For example a study on the comparative corrosion resistances of ductile and grey iron pipes carried out jointly by European pipemakers in 1964-1973 indicated a mean pitting rate of 0 -35 mm/y for uncoated ductile iron pipe exposed in a typical heavy Essex clay of 500-900 ohm cm resistivity for 9 years. This is clearly at odds with the rate of 1 mm/y normally found on a corroded service pipe from such a soil. The discrepancy appears to be due to the use of specimens that were only a third of a pipe length each and were buried separately. It may reflect the contribution of the total surface area of the pipe as a cathode to the corrosion current at the anodic area at the pitting site. 

Ductile-Iron and Gray-Iron Fittings for Water Supply Service C203 Coal-Tar Protective Coatings and Linings for Steel Water Pipelines-Enamel and Tape-Hot Applied... 

Table 3 Ductile cast-iron pipeline system for the transportation of waste water in drinking-water protection zones II [23]...

Embrittlement of service materials. The low temperatures inside storage tanks and transmission pipelines may cause significant susceptibleness of the structural material in vibrations and shocks. Mild steel and most iron alloys, at LH2 temperatures, lose their ductility being liable to increased risk of mechanical failure [50]. 

---