High-Density Cross-linked Polyethylene (XLPE)

Not all high-density polyethylene tanks are created equal. Although they sound nearly identical, linear polyethylene and cross-linked polyethylene (XLPE) chemical storage tanks have significant differences. Those differences could impact your organization’s bottom line, your people’s safety, and the operations of your facility.

Both linear polyethylene and XLPE tanks are made with heated resins to create a cured plastic. However, the differences in their production create very different polyethylenes with very different structural strength.

Cross-linking is simply the formation of bonds between the polymer chains. These bonds, equal in strength and stability to the principal bonds along the polymer backbone, tie the polymers together, thus dramatically increasing molecular weight. In fact, the length of the polymer chains and, therefore, the physical properties, are much better than can ever be achieved without crosslinking.

The result is a plastic that possesses impact resistance, tensile strength, and resistance to fracture that linear polyethylene just can’t match. These qualities make cross-linked polyethylene an excellent choice when tank integrity is critical. The structural integrity, heat resistance, and useful life in most cases are unparalleled.

Poly Processing has NSF-61 certification for 38 chemicals on its cross-linked polyethylene tanks.

XLPE VS. Linear Polyethylene (HDPE)

• XLPE has 10-20 times the environmental stress crack resistance of HDPE.
• It has 10 times the molecular weight of HDPE.
• It has 3-5 times the impact and tensile strength of HDPE.

XLPE VS. Fiberglass-Reinforced Plastic (FRP)

• XLPE offers seamless construction for greater strength.
• With FRP, chemicals can wick into the fiber, compromising tank life.
• XLPE can have a lower cost of ownership, due to the low amount of required maintenance compared to FRP.
• FRP often requires special handling to avoid cracking.

XLPE VS. Carbon and Stainless Steel

• XLPE has seamless one-piece construction, which eliminates the potential for chemical attack points and bad welds.
• Unlike carbon and stainless steel, XLPE has very broad chemical resistance capabilities without the need for high-cost coatings.
• XLPE requires limited routine inspection per the latest online Installation, Operation, and Maintenance Manual .
• XLPE is a cost-effective solution to high-priced alloys.

Additional Resources:

• Video: XLPE vs. HDPE When Pressurized
• Blog: Differences and Similarities of HDPE and XLPE
• Blog: High-Density Cross-Linked Polyethylene Testing Standards Explained
• Blog: The Tangible Difference Between HDPE and Crosslinked Polyethylene Storage Tanks
• Blog: 6 Differences Between XLPE and FRP Tanks

Learn more about the benefits of high-density cross-linked polyethylene tanks over fiberglass reinforced plastic tanks in our guide.