Differences between Cast Iron & Ductile Iron Pipe

While cast iron pipes were once considered the ‘gold standard’ for drainpipes, Ductile iron pipes have proven to be today’s superior choice.1 Ductile iron is known to be much more resilient, safe, and reliable, and when looking at the differences in choices, there’s no question about the new gold standard.  

Cast iron pipes were used regularly until the 1970s but are no longer installed in residential settings today due to cheaper and more reliable materials. While the disadvantages far outweigh the benefits of cast iron, there are still a few notable mentions. For one, cast iron pipes have the potential to last for over 100 years, but this is dependent on geographic location and care tended to the pipes. The duration of cast iron pipes can be extended if built into sandy soil, yet they are more likely to have corrosion much more quickly if built in clay soil. However, cast iron does, in fact, tend to be quite durable and strong, and many of the municipal pipelines and commercial buildings across the US still have cast iron pipes that work just fine. Lastly, cast iron is typically relatively quiet.  

The most common issue with cast iron pipe is deterioration or corrosion. The potential for a 100+ year service life is slim, while expected usage usually tends to be only about 40-60 years, while some utilities have found their pipes beginning to deteriorate as soon as 25 years.

Ductile iron pipes have benefits that far outweigh the disadvantages. The benefits of Ductile iron are the reason why it has become the new gold standard. First and foremost, Ductile iron presents a longer life cycle with expectations over at least 100 years, as opposed to the competitors that may reach half that. They require very little maintenance and provide significant cost savings and benefits in the long run, due to fewer interruptions and replacements, lower operational and maintenance costs, and lower energy costs. Ductile iron pipes also have better environmental performance due to lower greenhouse gas emissions in both production and operation while also being natural, safe, and sustainable. These pipes contain at least 90% recycled materials with the pipes themselves being 100% recyclable. Throughout its use, these pipes require less energy to pump water and therefore have a lower environmental impact overall. Ductile iron pipes do not absorb toxins like their plastic counterparts and thus provide better protection against drinking water contamination. And lastly, these pipes are much more resilient to extreme weather events, natural disasters, soil contamination, and other unpredictable situations. With its strength and durability, Ductile iron is the pipe of choice to protect against such ongoing stresses facing water utility systems.2  

When comparing Ductile iron and cast iron, it is obvious that Ductile Iron Pipe is the superior pipe. While some utilities may still have cast iron pipes, the life cycle of such is sure to be coming to an end, if not already. Ductile iron pipes have been proven as the environmentally superior, safer, more resilient, and best value of the choices at hand and will last much longer than the alternatives.

1 https://www.whittinspections.com/home-inspections/cast-iron-plumbing/

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