What is the difference between HDPE pipe and PVC pipe?

HDPE and PVC are both plastic materials commonly used in the manufacture of pipes. Both materials share similarities but have some key differences.

High density polyethylene (HDPE) is a strong, impermeable and flexible thermoplastic. HDPE is well suited for water and wastewater pipelines as well as oil and gas transmission systems. In fact, this reliable and durable material often replaces metal and concrete pipelines in these areas.

Polyvinyl chloride (PVC) has a higher tensile strength than HDPE pipes, but it is not necessarily stronger, even though it is stronger. Although PVC pipes have a higher tensile strength than HDPE pipes, they are much more brittle and vulnerable to fatigue cracking and breakage.

While there are cases where PVC pipes are better for certain applications, we believe HDPE pipes are the ideal choice for most water and wastewater applications.

HDPE Pipes vs. PVC Pipes in Various Conditions

HDPE is a natural gas-based thermoplastic, while PVC is a vinyl polymer. While both products are plastic products, HDPE is a more flexible and ductile pipe material. Below is a comparison of the physical properties of the two types of pipes and their reactions to various conditions.

Fatigue and Water Hammer

Both materials are designed to withstand standard pressure surges in pipelines. PVC pipes can withstand pressures 100 psi (pounds per square inch) above their pressure rating, while HDPE pipes can withstand twice as much pressure. HDPE pipes can withstand a flow rate of 14 feet per second (about 4.7 meters) before their pressure rating is reduced, while PVC pipes can withstand a flow rate of 5.5 feet per second (about 1.7 meters).

HDPE is 2,500 times stronger against water hammer and fatigue damage compared to PVC, so it is much less likely to crack or break over time.

Pressure Ratings vs. Working Pressure

PVC offers a high pressure rating for hydrostatic pressure, while HDPE offers a higher pressure rating for working pressures and higher flow rates. For flows above 5.5 feet per second (about 1.7 meters), HDPE should be compared to PVC for DR (pressure rating).

Bend Radius

HDPE pipes have a bend radius that can reach 25 times the pipe outer diameter, allowing them to form sharper curves than PVC pipes (200 times the outer diameter, 250 times for molten PVC). HDPE pipes are more flexible and adaptive to install.

Pipe Fusion vs. Bell & Spigot

HDPE pipes are joined using a heat fusion method, which means the pipes are heat fused together to form a seamless, one-piece, leak-free system that can withstand water level changes, earthquakes, freezing, and other ground movements. Because the fused joint is itself restrained, it does not develop weaknesses that are prone to leaks, excessive sag, over-insertion, and thrust cut-off problems, as bell & spigot joints do.

Viscoelastic vs. Amorphous

HDPE is a robust, flexible viscoelastic plastic that is well suited to piping work. PVC is amorphous and very strong, but has relatively low ductility and is brittle.

UV Protection

PVC is vulnerable to UV rays, which can cause the pipe to break over time. However, black HDPE pipes offer complete UV protection throughout their entire life cycle, from storage to transportation to construction.

Temperature

HDPE pipes can be installed and operated in extreme temperatures ranging from -40 to 140 degrees Fahrenheit. These temperatures apply to both the fluid passing through the pipe and the surrounding environment.

Advantages of Installing HDPE Pipes

In addition to a long lifespan of over 100 years, HDPE offers the following unique advantages during installation:

Narrow Trench Width: Compared to other pipe systems, HDPE pipes allow for the use of narrow trenches, making underground installation easier and more cost-effective. This is because the pipes can be connected from outside the trench and then lowered into it.

Safety: Because the trenches are so narrow and precise, trench block and brace installation is not required. There is no need for operators to enter the trench for pipe installation/connection.

Bit Wrench Installation: According to NASTT (North American Association of Bit Wrench Technicians), HDPE is the most widely used material for bit wrench installation. Thanks to the flexibility of the pipe, the shortest inlet and outlet pits can be used for bit wrench installation.

Versatility: HDPE is the only piping material that can be used for pneumatic pipe bursting due to its resistance to fatigue cracking.

While both PVC and HDPE are common piping materials, HDPE is the better option for most piping applications. Industries that use HDPE pipe include energy, natural gas distribution, mining, municipal, and communications.