HDPE vs. PVC Pipes
June 9, 2022
HDPE and PVC are both plastic materials commonly used to manufacture pipes. While the two materials share similarities, they have some key differences.
High-density polyethylene (HDPE) is a strong, impermeable, and flexible thermoplastic. HDPE is ideal for water and wastewater pipelines as well as oil and gas transfer systems. In fact, this reliable and durable material often replaces metallic or concrete pipelines in these applications.
Polyvinyl chloride (PVC) has a higher tensile strength than HDPE pipe, but stronger does not always mean tougher. While PVC’s tensile strength is higher than HDPE pipe, it is also a much more brittle product that is susceptible to fatigue cracking and failures.
There are times when PVC pipe will work in certain applications, but we believe HDPE pipe to be the ideal choice for most water and wastewater applications.
HDPE Pipes vs. PVC Pipes Under Different Conditions
HDPE is a natural gas-based thermoplastic, and PVC is a vinyl polymer. While they are both plastic products, HDPE is a more flexible and ductile pipe material. Below is a comparison of physical properties of the two types of pipe and their reactions to various conditions.
Fatigue and Water Hammer
Both materials are rated to handle standard pressure surges in pipelines. PVC pipe can handle 100 psi (pounds per square inch) above the pressure class, whereas HDPE piping can withstand two times the pressure. HDPE pipes can also handle a flow rate of 14 feet per second before the pressure rating reduces, while PVC pipes can only tolerate 5.5 feet per second.
Compared to PVC, HDPE is 2,500 times more resistant to damage from water hammer and fatigue, so the thermoplastic is far less susceptible to cracking and failure over time.
Pressure Class vs. Working Pressure
PVC has higher pressure classes for static water, but HDPE offers higher pressure classes for working pressures and higher flow velocities. For flows greater than 5.5 feet per second, HDPE should be compared DR for DR to PVC.
With a bend radius of 25 times the pipe’s outer diameter, HDPE pipes are capable of forming sharper curves than PVC pipes, which have a bend radius 200 times the outer diameter, or 250 times for fusible PVC. HDPE pipes can be installed with more flexibility and adaptability.
Pipe Fusion vs. Bell & Spigot
HDPE pipes are joined using heat fusion, whereby pipes are thermally fused to form a seamless, monolithic, leak-free system that can withstand changing water levels, earthquakes, frost, and other ground movement. Because the fusion joints are self-restrained, they do not create the same vulnerabilities as bell and spigot joints, which are susceptible to leakage, over-deflection, over-insertion, and thrust blocking issues.
Viscoelastic vs. Amorphous
HDPE is a viscoelastic plastic that is strong yet flexible, making it perfect for piping operations. PVC is amorphous and very strong, but it has relatively low ductility, which makes the material brittle.
PVC is vulnerable to UV radiation, which can cause pipes to break down over time. However, black HDPE pipes offer complete UV resistance throughout their lifecycle, from storage to shipment to implementation.
HDPE pipe can be installed and operated in both temperature extremes, from temperatures of -40 to 140 degrees Fahrenheit. These temperatures apply to the fluid running through the pipe as well as the environment around it.
HDPE Pipe Installation Benefits
In addition to HDPE’s long service life of over 100 years, the material offers unique advantages during the installation process itself:
- Narrow trench widths: Compared to other pipe systems, HDPE pipes allow narrower trenches, which result in easier and more cost-effective below-ground installation. This is because the pipes can be joined outside the trench and then lowered into it.
- Safety: Because the trenches are so narrow and precise, there’s no need for trench blocking and shoring. Workers are not required to go into the trenches to install/join the pipes.
- Trenchless installation: HDPE is the most widely-used material for trenchless installation, according to NASTT (North American Society for Trenchless Technology). The pipes’ flexibility allows for the shortest entry and exit pits for trenchless installation.
- Versatility: HDPE is the only piping material that can be used for pneumatic pipe bursting due to its resistance to fatigue cracking.
Contact WL Plastics for HDPE Pipes
Although PVC and HDPE are both common piping materials, HDPE is the superior option for most piping applications. Industries that rely on HDPE pipes include energy, natural gas distribution, mining, municipal, and communications. Contact WL Plastics today to learn more about our HDPE pipe manufacturing capabilities.