What is High-Density Polyethylene?

High-density polyethylene, or HDPE, is a natural gas-derived thermoplastic known for its impressive tensile strength, corrosion resistance, and impact resistance. These traits make it the ideal material choice for piping in a wide range of applications including pressure and non-pressure pipe, conduit and drainage. WL Plastics manufactures HDPE pipes for potable water systems, mining operations, oil and gas collection, wastewater removal, protecting fiber optic cables, natural gas distribution and more.

HDPE pipes are durable and resistant to physical damage, corrosion, common chemicals, and other environmental hazards. They are a cost-effective choice for long-term piping needs. Learn more about HDPE, including the material’s unique features, benefits, and applications.

Structure

High Density Polyethylene is a polymer. Polymer molecules are made of repeating chains called monomers. The monomer that makes up HDPE is ethylene, with the chemical formula of (C2H4)n. Catalysts are then added creating new ethylene co-monomers on the ends of the polymer chain. Since the polymer has a simple structure with minimal branching, it forms tightly packed chains that give the material its strength, flexibility, and stability. Because of its strength and durability, HDPE is the most widely used type of plastic, representing 34% of all plastic made. 

HDPE has a:

• Density of 0.944-0.965 g/cm3
• Tensile strength of >3500 psi
• Thermal coefficient of expansion of 8 x 10-6
• Maximum continuous use temperature of 140° F
• Slow Crack Growth Resistance PENT of >10,000 hours

Benefits of HDPE

HDPE is a ductile and strong pipe material that can stand up to harsh environmental conditions. This makes it both versatile and cost-effective for pipes, storage containers, and other applications.

LEARN MORE ABOUT THE BENEFITS OF HDPE

Malleability

HDPE stays solid and rigid until it reaches its high melting point, but once it reaches that point, it can be molded into any shape. This malleability allows HDPE to be made into everything from food packaging to playground equipment.

Easy Recyclability

HDPE is one of the easiest types of plastics to recycle, which helps companies take care of the environment and save costs. Recycling materials minimizes plastic production expenses and allows companies to market their products as more sustainable, which is an incentive for many customers.

Resistance to Environmental Factors

HDPE can withstand different weather and environmental conditions, including rain, common chemicals, acids, solvents, and detergents. Strong acids and bases can occur naturally in soil, so HDPE pipes are a suitable option for underground piping.

HDPE water supply pipe

Applications of HDPE in Piping

HDPE is an excellent material for pipes in a range of settings.

Agriculture and Irrigation

HDPE piping can provide irrigation for gardens, farms, and other settings. This includes intake and delivery pipes for flood irrigation and sprinklers for watering crops, lawns, gardens, or golf courses. For orchards and nurseries that require drip irrigation, HDPE piping is both strong and lightweight. 

Potable Water Transportation

Using HDPE to transport drinking water avoids the risk of corrosion that comes with metal piping while maintaining a leak free system.

Sewage, Waste, and Industrial Effluent Disposal

HDPE pipes are a good solution for residential sewage disposal, fertilizer transportation, and waste disposal in the petrochemical industry. H2S gas from these applications does not harmfully affect HDPE pipe.

Electrical and Communications Conduits

HDPE piping can provide secure coverage for electrical and telecommunications cables because of its resistance to water and other environmental hazards. The material can prevent cable malfunctions due to damage.

Drainage Pipes

Piping to drain surface water, rainwater, and subsoil water needs to be strong and corrosion-resistant. HDPE pipes work well for drainage as well as wastewater mains.

Gas Mains/Distribution

Polyethylene pipes are the most commonly used pipe in the transfer and distribution of natural gas to customers. This is because of its leak-free joining system, strength,  flexibility and low cost.

HDPE vs. Other Materials

To fully understand the benefits of HDPE, consider the material in comparison with its common alternatives in water applications.

Ductile Iron

Ductile iron is commonly used for industrial water and sewage pipes. The main benefit touted by ductile iron manufacturers is its tensile strength being higher than other types of thermoplastics. However, it is more expensive and susceptible to corrosion. 

PVC

PVC is a vinyl polymer, while HDPE is a thermoplastic. PVC has a higher tensile strength than HDPE pipe but is less flexible. PVC is not resistant to UV damage and is susceptible to fatigue failures due to surge events. PVC and ductile iron both use bell and spigot joints which can leak where HDPE pipe has a fused joint system that is leak-free.