Various types of pipe materials are available in the market, but two are found to be used frequently. One is found in most traditional homes, and the other is used in almost all modern houses; they are cast iron and plastic pipes. Therefore, while selecting material for the pipes, consider all the aspects of plastic pipe vs cast iron pipe.
There are significant differences between the two types of pipes, so understanding all aspects associated with each pipe is critical. While choosing the material for piping, factors such as the character of the water it will carry, the relative cost compared with its useful life, and the nature of the soil in which the piping is to be laid has to be considered. The material shall be resistant to corrosion, both outside and inside, or shall be suitably protected against corrosion. Each pipe has its strengths and weaknesses; their durability in service is dependent on the installation environment, the nature of the water passing through them, and how well they are installed.
Hence, in this article, we have discussed the comparison of cast iron vs PVC pipe. This comparison will help you select the right pipe for your home.
Plastic Pipes vs Cast Iron Pipes
The below points on plastic pipes vs cast iron pipes will help you in differentiating them:
General
Plastic Pipe
According to Subhash M. Patil (author of Plumbing Engineering), plastic pipes are becoming more common due to their properties of corrosion resistance, lightweight, and pocket-friendly. Plastic pipes have their own merits and limitations.
Cast Iron Pipe
It can be identified by its dark colour, rough texture, and large surface. Cast iron is an alloy metal made of iron, carbon, and silicone. Because it’s not malleable, it is cast (hence the name) in a mold to create things like pipes, etc.
Size
Plastic Pipe
The pipes are manufactured in sizes from 17 to 609 mm. However, the sizes most commonly used are 21.2 mm, 26.6 mm, 33.4 mm, 42.1 mm and 60.2 mm (outside diameter).
Cast Iron Pipe
The nominal inside diameters of cast iron pipes available are 50,65,75,90, 100,125 and 150 mm.
Durability
Plastic Pipe
Plastic pipes have less durability when compared to cast iron pipes. According to Mehdi Farshad (author of the book Plastic Pipe Systems: Failure Investigation and Diagnosis), depending upon the conditions of use, polymer-based pipe systems have a service life of 50-100 years.
Cast Iron Pipe
Cast iron pipes have high durability as compared to plastic pipes. Homes as old as 80-100 years have cast iron drainage pipes that are still intact and functional.
Adjustability
Plastic Pipe
Plastic pipes cannot be adjusted after installation. Hence if there are any changes, a whole section of pipes has to be replaced. This poses a major challenge while remodeling the house.
Cast Iron Pipe
Cast iron pipes have high adjustability. They can be re-oriented and adjusted even after installation. This helps when you have to remodel the house, as the required pipes can be changed easily.
Know more about cast iron pipe with our detailed article:
Fire Resistance
Plastic Pipe
Plastic pipes are less fire-resistant as compared to cast iron pipes. In cases of house fires, it can easily burn and start melting, thereby creating an opening through which flames can move from one part of the building to the next.
Cast Iron Pipe
Cast iron pipes have a very high resistance to fire. They will not melt when there is a house fire. Cast iron pipe prevents the spread of fire much better than plastic pipe because it is not combustible.
Environmental Concerns
Plastic Pipe
Those who want an environment-friendly structure should avoid the use of plastic pipes, as they are not eco-friendly. The production of plastic releases harmful gases into the atmosphere.
Cast Iron
Cast iron is an eco-friendly material. They can be made out of scrap iron, and they can also be recycled after their service life is over.
Cost
Plastic Pipe
Depending upon the thickness and quality, the cost of plastic pipes varies from INR 100 – INR 1000 per piece.
Cast Iron
The cost of cast iron pipe is INR 700 – INR 4000 per piece, depending on the thickness and the manufacturers. Cast iron pipes are more expensive than plastic pipes.
Expansion Joints
Plastic Pipe
As compared to cast iron pipes, plastic pipes have a higher coefficient of expansion and contraction. Hence, for pipes more than 30 feet, an expansion joint has to be provided.
Cast Iron
Cast iron pipes have a low coefficient of expansion and contraction; hence, there is no need for expansion joints in cast iron pipe systems.
Noise
Plastic Pipes
Plastic pipes are light in weight, and when water flows through them under high pressure, there may be vibrations that produce some noise.
Cast Iron Pipes
Cast iron pipes are quite heavy, and hence even if the water flows through them under heavy pressure, there will be no vibration. Hence, one need not worry about noise with cast iron pipes.
Talking about noises in pipes, we have a detailed article on its reasons. Make sure to check it out:
Use in Earthquake-Prone Areas
Plastic Pipes
Plastic pipes are preferred in areas that are prone to earthquakes, as they are light in weight.
Cast Iron Pipe
Cast iron pipes are heavier compared to plastic pipes. Hence, they are not suitable for earthquake-prone areas.
Water Friction
Plastic Pipe
Plastic pipes have a smooth surface, which results in less fluid friction and a more consistent flow. So there is less energy loss with plastic pipe, and the performance of the pipe is better.
Cast Iron Pipe
Cast iron pipes have a relatively rough surface when compared with plastic pipes.
Advantages
Advantages of Plastic Pipes
- The major advantage of plastic pipes is that they are less expensive when compared with other pipe materials.
- Plastic pipes are lighter than cast iron pipes.
- They can be easily cut.
- Because of its light weight and ease of use, transportation and installation are simple.
- Plastic pipes require a lesser number of joints.
- Due to their smooth surface, plastic pipes have better performance as energy loss is lower.
Advantages of Cast Iron Pipes
- Cast iron pipes are more durable as compared to plastic pipes.
- They have greater strength than plastic pipes.
- They have a low coefficient of expansion/contraction
- Cast iron pipes are fire-resistant and do not get burnt during house fires.
- It is an environment-friendly material.
Disadvantages
Disadvantages of Plastic Pipes
- Caution must be exercised when using plastic pipes that are close to water heaters and similar heat sources.
- Most plastic pipes are not rated for use for drinking water, not due to a high risk of toxicity but due to the fact that they can degrade with UV light exposure, high temperatures, and extremely high pressures.
- The production of plastic pipe is not friendly to the environment.
- They have less durability as compared to cast iron pipes.
Disadvantages of Cast Iron Pipes
- They are more expensive.
- Cast iron is heavy and difficult to cut and fit.
- They are available in short lengths.
- The interior of the pipe becomes rough with age, so the carrying capacity is reduced.
- Corrosion can damage pipes.
Manufacturers
Plastic Pipe
The standard manufacturers of plastic pipes are,
- Astral poly technik Ltd.
- Finolex industries Ltd.
- Prince pipes and fittings Ltd
- Jain irrigation systems Ltd
Cast Iron Pipe
The standard manufacturers of cast iron pipes are,
- Jupiter Metal Industries(Jal.)
- Kapilansh Dhatu Udyog (P) Ltd
- Jayswal Neco Industries Ltd.
Takeaway on Plastic Pipe VS Cast Iron Pipe
With such a detailed comparison between cast iron and plastic pipe, this article will help you select the suitable pipe for your home. Each pipe has its strengths and weaknesses; their service durability depends on the installation environment, the nature of the water passing through them and how well they are installed. An older home’s plumbing system may be dominated by cast iron, while a new home will have plastic pipes of various types used almost exclusively. Cast iron pipe is typically used for municipal water and sewer lines, but nowadays, it has been replaced by HDPE (high-density polyethylene) pipe.
The plumbing pipe system for any home can take into account a variety of different materials. The choice between cast iron vs PVC pipes can be influenced by factors including the age of the home, the homeowner’s financial resources, and the geographical location of the home itself. Hope this article has provided you with a better understanding of plastic pipe vs cast iron pipe.
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