End users are appreciating corrosion resistance and other benefits of pultruded products

The Waterpark of America in Bloomington, Minn., needed several platforms and stair towers that would be exposed constantly to chlorinated water. Officials at the new entertainment destination wanted to keep the park attractive while limiting the need for constant maintenance. They wanted their structures to attract kids, not corrosion. They wondered: Would aluminum work?

At the same time, across the country in Indian Wells, Calif., a country club community called The Vintage Club had pyramid-shaped screens on its rooftops to conceal air-conditioning units. The screens, constructed from structural timber, deteriorated quickly and required $75,000 in maintenance costs every other year. They wondered: Was there a more effective, long-term replacement?

Both organizations were about to experience the power of pultrusion.

The architectural firm in charge of the waterpark’s design explained that aluminum extruded shapes can cause galvanic corrosion, and that in contrast, pultruded composites are highly corrosive-resistant. In addition, the firm explained, pultrusions are electrically and thermally non-conductive, impact-resistant and EMI/RFI-transparent. The firm installed DURAGRID pultruded fiberglass vinyl ester grating, developed by Bristol, Va.-based pultruder Strongwell, to serve as flooring on the waterpark’s platforms. It also installed skid-free DURAGRID stair treads.

At the country club community, leaders at an industrial plastics distribution firm explained how pultruded fiberglass doesn’t rot or decay. In addition, the company said, pultruded composites would be stronger, more rigid and lighter than the club’s timber screens. Because pigments are added to the resin during the pultrusion process, the club’s beige color could be included throughout the part, so continual painting wouldn’t be necessary.

Corrosion resistance is certainly a big deal for many industries, and it’s one reason why composites firms are interested in pultrusion applications,” says Dan Witcher of Strongwell, which publishes a Corrosion Resistance Guide to help industry pros develop customized solutions. “Companies that can recognize ideal applications for pultruded products and can explain the benefits to engineers and end users are definitely well-positioned to grow business.”

Success Today Requires More Than the Machine

Pultrusion is a manufacturing process for producing continuous lengths of reinforced polymer structural shapes with constant cross-sections. The process involves pulling the liquid resin mixture and flexible textile reinforcing fibers (rather than pushing them, as is the case in extrusion) through a heated steel forming die, using a continuous pulling device.

The reinforcement materials are in continuous forms such as rolls of fiberglass mat and doffs of fiberglass roving. As the reinforcements are saturated with the resin mixture (“wet out”) in the resin bath and pulled through the die, the gelation of the resin is initiated by heat from the die. A rigid, cured profile is formed that corresponds to the die’s shape.