Published 1/22/2019

Tecnofire adds fire resistance to transportation and infrastructure applications

Intumescent nonwoven veils improve the fire performance of composites in bridge, bus, building, marine and aircraft structures.

Ginger Gardiner

Senior Technical Editor, CompositesWorld

The Whitestone Bridge (the Bronx, NY) uses Tecnofire intumescent nonwovens in its FRP wind fairings (white curved panels along left side of bridge deck), reducing load on the bridge by 6,000 metric tonnes vs. steel.

SOURCE | CW

North American Bus Industries (NABI) chose Tecnofire to protect the resin-infused vinyl ester composite doors and wheel wells of its CompoBus. This sample panel shows typical construction for such parts: a gelcoat or paint as the outer surface, followed by Tecnofire with a resin matrix, an outer skin using glass or other fiber, a core material and then an inner skin.

SOURCE | TFP

When Tecnofire intumescent nonwoven veils reach 190°C, they expand in the z-direction up to 35 times their thickness, providing a protective char that helps composites meet the most demanding fire resistance requirements.

SOURCE | TFP

Tecnofire intumescent nonwovens are available as roll goods up to 50 inches wide or slit into tapes and also as 4x8 sheets with resin already infused into it.

SOURCE | TFP

Tecnofire is a family of intumescent nonwoven veil products made by Technical Fibre Products (TFP, Burneside Mills, UK and Schenectady, NY, US). They have been used in a variety of applications, including fiberglass-reinforced plastic (FRP) wind fairings on the Whitestone Bridge in the Bronx, New York City (Fig. 3). Steel fairings that slice and deflect wind that buffets the bridge were replaced with FRP, cutting weight to reduce load on the bridge by 6,000 metric tonnes. Designed by Gurit US (Bristol, RI) and manufactured locally, the composite fairings covered 20,000 m² of the bridge’s surface. “Each fairing was faced with Tecnofire to provide fire protection,” recalls Klopfer. “It was a drop-in solution. All they had to do before installation was paint the outside.”

Klopfer sees an uptick in architectural and construction applications, especially interior wall and panel designs where the materials must stop flame propagation to allow occupants time to exit. “Traditional materials have been entrenched for so many years,” he says, “but now there is a movement to reduce weight. There are advanced FR resins, including systems from Polynt and Ashland, but we see that designers want to use a combination of fire resistance strategies — for example, an FR resin with Technofire.” TFP has shown that with Tecnofire alone, lightweight composites can pass the common building fire standards per ASTM E119 and NFPA 285/286 tests. “We also ran the ASTM E84 test on Tecnofire and got zero flame spread with very little smoke. We can lower the heat release rate by up to 40% and increase the time to ignition by 40%.”

This kind of performance has also helped Tecnofire into several marine programs and airframes, the latter proving the material’s ability to withstand long-term exposure to aggressive fluids (e.g., jet fuel, hydraulic fluid, solvents). TFP has also adopted methodologies for smaller-scale, indicative testing in advance of full-scale tests in order to downselect composite designs better optimized to meet the fire resistance requirements of a final assembly.