What Is “Dual Laminate” Fabrication?

This is where dual laminate fabrication comes in. Dual laminates combine the reliable corrosion protection of an interior plastic liner with the structural integrity and durability of FRP fiberglass reinforcement. In combining these two materials, you get the best of both worlds. Dual laminate equipment is lightweight and durable, and able to operate in harsh conditions or extreme temperatures where metal or plastic alone would fail. Unlike metal tank exteriors, which often corrode over time—think municipal water towers—the FRP exterior of dual laminates offers exceptional durability. They also provide a lower-maintenance alternative to glass-lined, rubber-lined, and brick-lined systems.

Another advantage of dual laminates is that they can be shaped into an unlimited number of configurations. Unlike metal, which which offers inherent geometric restrictions, dual laminates can be formed and shaped into any conceivable configuration, making them an ideal choice for custom parts that would be difficult to find or fabricate elsewhere. Unlike metal pipes, which can only be made to certain lengths, dual laminate piping can be fabricated to any length a single continuous run without the use of flange connections. This can reduce or eliminate the need for flanges, which often prove problematic for long-term maintenance and reliable leak prevention.

And most importantly, dual laminates are cost-effective, especially when compared to high nickel alloy metals. Not only are the raw materials more affordable, but the equipment needed is less specialized and less expensive. This makes dual laminate fabrication an attractive option in a wide variety of applications, as they offer extreme chemical resistance, mechanical toughness, durability, and ease of fabrication, all at an unrivaled value.

Once the plastics and FRP resin have been sourced, the fabrication process begins by forming and welding the thermoplastic linings (in roll or sheet form) into shape. Welding technologies include hot gas hand welding, flow fusion machine welding, and butt fusion machine welding. Typically, these thermoplastic sheets or rolls are fabric-backed, which provides a better surface for the adhesive that joins the fabric to the fiberglass.

Once the lining is complete, it is internally supported and FRP is chemically or mechanically bonded to the lining. The FRP bond to the thermoplastic lining must have minimum climbing drum peel strength of 50 in.-lb/in. when tested per ASTM D 1781. Typical methods include filament winding (i.e. wound around a spinning mandrel), hand layup (which requires a skilled operator to perform), or vacuum infusion molding processes. This FRP layer is then typically treated with a corrosion-resistant barrier that provides secondary corrosion protection behind the thermoplastic lining.

The piece is then tested to ensure that there are no gaps or weak spots along welded areas. A conductive carbon veil layer is integrated into the FRP corrosion barrier to facilitate high voltage spark testing of the lining. The conductive target should cover 100% of the lining.

Interested in using dual laminate materials in your next project? Visit our Member Directory to find a company (or companies) that can help you find success with dual laminates!