HDPE vs PVC: Key Differences in Properties and Applications

Which is better, PVC or HDPE?

As a trusted pipe manufacturer in the UAE, we have been asked countless times which of the two material types is better. However, the answer isn’t as simple as choosing one over the other.

Both materials offer advantages in terms of durability, flexibility, and cost, but they cannot be used interchangeably. It’s important to understand the characteristics of each material so you can identify the most suitable one for your purpose.

In this guide, we’ll explain the key differences between PVC and HDPE in terms of characteristics and usage. We’ll also tackle the common questions people ask about these piping materials to help you make an informed decision for your next project.

PVC vs. HDPE: How Do They Differ?

PVC, or polyvinyl chloride, is a plastic made from vinyl chloride. It is extremely common and costs less than almost any other type of plastic material, making it a popular choice in pipe manufacturing.

On the other hand, HDPE — short for high-density polyethylene — is a thermoplastic polymer crafted from petroleum. It has a high melting point and is impact-resistant due to its high strength-to-density ratio.

PVC and HDPE have different chemical compositions due to their manufacturing. This also impacts their durability, flexibility, and other properties. Below is a breakdown of how these plastic materials compare.

Manufacturing

PVC manufacturing uses various processes, such as emulsion, bulk, suspension, and dispersion — each producing different PVC grades — and requires plasticizers, lubricants, fillers, and stabilizers. You can learn more about it in our guide on how PVC pipe is made.

Meanwhile, manufacturers use gas-phased and slurry loop polymerization to turn ethylene into HDPE. Unlike PVC, it doesn’t require stabilizers or plasticizers, making the manufacturing process simpler and more material-efficient (since fewer additives are needed).

Durability and longevity

Whether your pipes are made from PVC or HDPE, they will last for 50 years or more. If manufactured, installed, and maintained properly, they can even last up to 100 years.

Of course, there are still certain differences in how sturdy they can be based on specific conditions.

For instance, HDPE is known to have higher overall chemical resistance compared to PVC (more on this later). It is also the better choice for applications where environmental stress cracking is involved. Even so, PVC can be quite durable when reinforced and formulated according to its application.

In terms of water hammer and fatigue, both materials can withstand standard pressure surges. However, there are still significant differences between them:

• PVC pipes and fittings can handle up to 100 psi (pounds per square inch) of water pressure and 5.5 feet per second of flow rate.
• In contrast, HDPE can take a water pressure of up to 200 psi and a flow rate of 14 feet per second.

HDPE is also 2,500 times more damage-resistant to water hammer and fatigue than PVC, making it less likely to crack over time.

Flexibility (bend radius)

Flexibility is another essential factor to consider for plastic pipes because of how they are used. In this case, HDPE reigns supreme because it can bend to form sharper curves compared to PVC.

To understand this, you need to understand bend radius — the minimum radius of the inner curvature of a material (e.g., pipes, tubes, cables, sheets, etc.) without getting damaged. Here’s how the two materials compare:

• HDPE can bend up to 25 times the outer diameter of the pipe,
• PVC and fusible PVC have a bend radius of 200 times and 250 times the pipe’s outer diameter, respectively.

Remember: The lower the number in the bend radius, the higher the pipe’s flexibility.

Joining

PVC and HDPE also differ in how they are connected.

Where PVC can be joined together using gluing sealant or gaskets, HDPE can only be connected via heat fusion. While this makes PVC a more convenient choice for underwater installation, HDPE is the better option when it comes to the durability of connections.

Chemical compatibility and resistance

As mentioned earlier, HDPE has relatively better chemical resistance than PVC. Of course, it’s still a matter of the type of chemical they are exposed to.

Both materials have the same chemical resistance to acetic acid, ammonium sulfate, and ammonium hydroxide. They are also in the same league when exposed to:

• Borax
• Calcium hypochlorite
• Hydrochloric acid
• Hypochlorous acid
• Phosphoric acid
• Sodium bicarbonate
• Sodium carbonate
• Sodium chloride
• Sulfur
• Urine
• Water
• Saltwater

However, HDPE is more resistant to nitric acid, lubricating oil, and sulfuric acid (at most concentrations), while PVC can better handle sodium hypochlorite and chlorine at 50+ ppm (parts per million).

Usage and application

Another important factor to consider when choosing a plastic pipe is its application. Although they are all tubular-shaped plastic, pipes made for electrical applications cannot be used interchangeably with firefighting pipes and gas distribution piping.

Both can be used in piping systems, but HDPE dominates the gas and water distribution sector. PVC is better suited for sewer networks and drainage pipes (in drain, waste and vent or DWV, and municipal wastewater systems).

HDPE vs. PVC FAQs

Here, we’ll answer some of the most commonly asked questions about PVC and HDPE pipes.

What are the advantages of HDPE pipes over PVC pipes?

Aside from withstanding shock waves better than PVC, HDPE is usually the better choice because:

• It has a low-temperature impact, allowing it to better handle season stress (hot and cold weather conditions).
• It is more UV-resistant than PVC.
• It is sturdier even when exposed to corrosive materials, sand, salt, and dust.

As mentioned before, HDPE also has better flexibility and tighter bend radius because of its malleability.

Which is more expensive: PVC or HDPE?

When comparing HDPE versus PVC prices, you shouldn’t just focus on the upfront costs. To know which of the two is more expensive, you must also consider how cost-effective these materials are.

Case in point, HDPE may have a higher price tag compared to PVC. Even so, it is considered more cost-effective because:

• HDPE doesn’t require additional fittings since it is joined using heat. There is also no need to wait for the glue or cement to cure.
• It is more time-efficient and cost-effective to transport since it is UV-resistant and doesn’t need to be covered.

More importantly, HDPE tends to last longer in most applications than PVC, reducing repair and replacement costs in the long run.

Make the Right Choice

Your decision between using PVC or HDPE pipes should always depend on the exact usage and your specific needs.

Once you understand the key differences and distinct advantages of these materials, you should be able to make the right choice for your requirements.

For more information specific to your project, talk to our experts at Polyfab Plastic Industry. We’re always here to help.