PVC Versus Cast Iron Piping
Piping for plumbing systems in commercial buildings has come a long way. The very first plumbing pipes were made of a combination of baked clay and straw. As you may have guessed, however, these plumbing pipes weren’t the most durable and had frequent issues.
Nowadays, if you’re building a commercial structure, there are several different types of plumbing pipes to choose from. The most common of these are PVC and cast iron, both of which have been used for years.
While PVC and cast iron are the most common materials used in the commercial plumbing industry, it’s important to know which one is right for you. In this article, we’ll explore how and why these two materials are used, as well as the pros and cons of each. We’ll also give you a list of factors to consider in order to help you make your choice.
Cast Iron Piping in Commercial Buildings
For years, cast iron was the only piping material that could be reliably used in the plumbing industry. Cast iron is made of gray cast iron that is cut, shaped, and molded into a round shape with a hollow center. From the 17th to 20th centuries, cast iron pipe was used for a wide variety of plumbing purposes, including drain lines, sewage, water lines, and more.
Today, however, cast iron pipes are rarely used in residential settings, such as houses and condos. They’re simply overkill because residential properties typically don’t need plumbing pipes that are that big and robust. In commercial buildings, however, cast iron pipes are still used for sewer lines, drain lines, and water lines that have excessively high pressure. In these commercial buildings, plumbers have much more of a need for accessories like camlock fittings, corrosion resistant ball valves, or PVC duct fittings.
Pros of Using Cast Iron Piping
Durability
In terms of overall durability, cast iron can’t be beaten. Cast iron has a life expectancy of at least 50 to 65 years and can last even longer in some instances.
Strength
Cast iron piping is also the strongest type of piping available for commercial buildings. It has a hard outer shell of iron that can survive anything short of a blow from a sledgehammer.
Heat Resistance
Cast iron is also the most heat-resistant plumbing material on the market. It can withstand temperatures of up to 650 degrees Fahrenheit, which is substantially higher than anything you’ll run into in water, sewer, or drainage situations.
Low Maintenance
In addition to being extremely durable, cast iron piping is also very low maintenance. Once it’s installed, there’s very little you need to do in terms of maintenance. The only thing you might need to do occasionally is perform a drain cleaning, but this is only performed as needed.
Cons of Cast Iron Piping
Cost
While cast iron is highly durable and great for high-pressure and high-heat situations, its cost reflects that fact. Cast iron pipe can cost anywhere from $10 to $30 per square foot, depending on where you buy it. The cost to install cast iron is also substantially higher than PVC because it’s more labor-intensive.
Corrosion
While cast iron is strong and can withstand almost anything, it is prone to corrosion. Corrosion typically happens from the inside out, as little chunks of the inside of the pipe get eaten away through the years by hard water.
Weight
Finally, the reason that cast iron is so expensive and tough to install is that it’s incredibly heavy. As such, it requires more support and a stronger overall support system.
PVC Piping in Commercial Buildings
PVC piping has overtaken cast iron as the most common piping material used in the commercial plumbing industry. PVC pipe stands for polyvinyl chloride pipe, and it consists of a combination of plastics and chemicals. It is typically used for sewage, drainage, and water line systems in commercial buildings.
Pros of PVC Piping
Corrosion Resistant
Unlike cast iron, PVC is resistant to corrosion because it doesn’t include any metal or iron components.
Weight
Because it’s mostly made of plastic, PVC pipe weighs a fraction of what cast iron does.
Cost
In addition to being lighter and resistant to rust, PVC is much cheaper than cast iron. PVC typically costs anywhere from $2 to $10 per square foot, depending on the size, thickness, and where you buy it from.
Moldability
Where cast iron is rigid and stiff, PVC is slightly moldable, depending on your needs. It’s also more flexible than cast iron, which is important in certain implementations.
Durability
PVC is also one of the most durable plumbing materials on the planet. Its unique combination of plastics and chemicals results in a pipe that can last for up to 100 years, as long as it’s protected and maintained.
Ease of Installation
Because of how lightweight and easy to cut and handle PVC is it’s much easier to install. It also requires fewer supports! As such, in addition to being easier to install, it’s also much cheaper.
Cons of PVC Piping
Strength
While PVC is extremely durable, it’s more prone to damage than cast iron. Over time, it can get brittle, and the connecting joints are also weaker and more prone to damage than those of cast iron.
UV Resistance
In addition to not being quite as strong, PVC also isn’t resistant to UV radiation from the sun, whereas cast iron is.
What To Consider When Choosing Piping for Commercial Properties
Now that you know the strengths and weaknesses of PVC and cast iron, let’s look at how to choose which material is right for you.
UV Exposure
If your piping is going to be exposed to the sun, it’s best to use cast iron. Or you can install PVC and paint or wrap it with a special protectant, but these need to be reapplied periodically.
Flexibility
There are also certain plumbing situations where your drain, water, and sewer pipes need to bend and flex. In these situations, you must have PVC because cast iron is not flexible.
Temperature and Pressure Requirements
In situations where your pipe will be exposed to extremely high temperatures, you may need cast iron. PVC can withstand temperatures of up to 140 degrees, whereas cast iron can withstand up to 650 degrees.
Volume
Because cast iron is stronger, heavier, and thicker than PVC, it can handle higher volumes of water, as well as higher water pressures.
Durability and Performance
Cast iron and PVC are both extremely durable and perform well in different ways. Cast iron is stouter and UV-resistant and can handle heavier loads, whereas PVC isn’t prone to corrosion, is more lightweight, and lasts longer than cast iron. Therefore, it’s important to consider what type of performance you need from your plumbing pipes as well as what types of elements they will be subjected to.
Repairs and Replacement
Finally, PVC piping is much easier and cheaper to repair and replace than cast iron. Therefore, if you’re worried about ongoing costs and repairs, PVC is the way to go.
In general, PVC is the material of choice when it comes to plumbing systems in commercial buildings. Its combination of affordability, durability, and performance makes PVC a better option than cast iron, unless you have a situation that specifically calls for it.
Mark Ligon is the marketing manager at Commercial Industrial Supply, a supplier of commercial and industrial piping, fittings, valves, filtration products, and accessories. Ligon enjoys educating businesses on the specific parts of piping systems so managers can make informed decisions.