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Water/Wastewater Conveyance
Published in Frank R. Spellman, Handbook of Water and Wastewater Treatment Plant Operations, 2020
Ductile-iron pipe resembles cast-iron pipe in appearance and has many of the same characteristics. It differs from cast-iron pipe in that the graphite in the metal is spheroidal or nodular form, that is, in ball-shape form rather than in flake form. Ductile-iron pipe is strong and durable; it has high flexural strength, good corrosion resistance, is lighter weight than cast iron, with greater carrying capacity for the same external diameter; and is easily tapped. However, ductile-iron pipe is subject to general corrosion if installed unprotected in a corrosive environment (Gagliardi & Liberatore, 2000).
Characterizing the Distribution System: Microbial Issues
Published in Edwin E. Geldreich, Microbial Quality of Water Supply in Distribution Systems, 2020
Service life of these pipe materials will vary, being related to water chemistry, microbial activity, soil corrosivity, climatic conditions, and vibrations around the street bedding site. Cast-iron and ductile-iron pipe appear to have a service life of approximately 100 years; reinforced concrete, 50 years; and asbestos cement pipe, 30 years. Little can be said with any degree of certainty about the service life for plastic pipe because it has been slow to gain wide acceptance by most utilities.
Combining recorded failures and expert opinion in the development of ANN pipe failure prediction models
Published in Sustainable and Resilient Infrastructure, 2023
Sean Kerwin, Borja Garcia de Soto, Bryan Adey, Kleio Sampatakaki, Hannes Heller
The seasonal effects on pipe failure have also been well documented by numerous water utilities and in published reports (Infraguide, 2002). Seasonal temperature changes cause soil movement, commonly referred to as frost heave, which leads to increased stress on pipes and often causes old cast iron pipes to break. Ductile iron pipes are more malleable and can better handle such stress fluctuations. This trend is visible in the failure data. Figure 7 contains the average monthly failures by material type and by failure type. Cast iron failures peak in December and January, and so do rupture failures. Corrosion-caused point failures and the corresponding number of ductile iron failures greatly increase in spring and summer when the moisture content of the soil is higher, which facilitates the redox reactions necessary for corrosion to take place.