Cast Iron Pipe vs. PVC Pipe

July 31, 2017

If you've not seen the guts of an old home, I'm talking about one built before 1920, you might not have ever seen cast iron drain pipes. It was the gold standard piping material used by plumbers for larger drain and vent lines for decades. But the chemical industry explosion that happened in the 1960's changed the course of plumbing. Some may argue not for the better.

Iron vs. Plastic: The Real Story

July 31, 2017

The debate over which DWV pipe to choose has continued for decades. The discussion is generally centered on two piping materials - cast iron soil and plastic. As a representative of the Cast Iron Soil Pipe Institute, I obviously have a strong preference for cast iron. At the same time, I acknowledge the manufacturers of plastic pipe make products which serve useful functions in today's construction industry. 

Cast Iron vs. PVC - How Much Would You Pay for Quieter Pipes?

May 07, 2018

Cast Iron vs. PVC - How Much Would You Pay for Quieter Pipes?

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Outstanding Fire Resistance
Cast iron pipe prevents the spread of fire much better than plastic pipe because cast-iron is not combustible. It will neither support a fire or burn away, leaving a hole through which smoke and flames can rush through a building. On the other hand, combustible pipe such as PVC and ABS, can burn away, Firestopping from the combustible pipe is labor intensive, and the materials are expensive, but fire-stopping for cast iron pipe, a noncombustible pipe, is relatively easy to install and inexpensive.

Superior Sound Insulation 
Cast iron's molecular density silences the noise, and the rubber gaskets used to join the pipe reduce the transmission of vibration through the system. Independent tests show that cast iron pipe joined by rubber gaskets can reduce plumbing noise 750% better than plastic pipe. Because of this quietness, the October 4, 1977, edition of the Chicago Tribune identifies cast iron soil pipe as one of the "hallmarks of quality" in home construction.

Environmentally Friendly
After their useful life, cast iron drainage pipes and fittings are recycled at practically 100%, and they have been produced from 95% used cast iron for decades. Cast iron has been a recycling product in the modern sense of the term for centuries. Most plastic pipes, however, are not recycled, but burnt or disposed of at waste sites. For the manufacture of HDPE drainage pipes, manufacturers use exclusively new material, as the existing recycling plastic material is not up to the requirements.

Low Expansion Ratio
One of the major reasons engineers and architects prefer cast iron soil pipe is for its low coefficient of expansion and contraction. Cast iron expands and contracts at about the same rate as concrete and steel, approximately 1/4 inch per fifty feet within a 70-degree temperature change, contrasted to plastic pipe, which will expand and contract the following lengths: PVC 2.338 inches and ABS 2.362 inches, Consequently, when plastic pipe is used in runs of more than 30 feet, expansion joints are usually required. But no expansion joints are ever needed for cast iron soil pipe systems.

Long Service Life
One of the most impressive qualities of cast iron pipe is its longevity. Because plastic pipe has been installed in large quantities only since the early 1970s, its service life has not yet been determined. However, cast iron pipe has been used since the 1500s in Europe. As a matter of fact, cast iron pipe has been supplying the fountains of Versailles in France for over 300 years.

Adjustable Fittings
One of the amazing aspects of the modern cast-iron pipe is the fact you can easily adjust the orientation of the fittings AFTER you install them. You can do this by just loosening the screws on the band clamps and then twisting the fitting. It's IMPOSSIBLE to do this with PVC or old cast iron. Once you glue PVC together you have between five and two seconds, depending on the diameter of the pipe, to make any adjustments.

© 2017 by HENGTONG PIPE AUSTRALIA Pty. Ltd. Proudly created with Owen Zhao

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