FRP grating – moulded & pultruded

What it is

FRP (fibreglass reinforced plastic, also called GRP) grating is a floor and walkway panel made from continuous glass fibre bound in a thermosetting resin. It is used where steel bar grating would corrode quickly or where a metal floor is not wanted: wastewater and water treatment plants, chemical and fertiliser plants, marine wharves and jetties, mine processing areas, cooling towers, electrical switchyards and substations, and food plants with frequent washdown.

World Steel does not manufacture FRP. We source FRP grating from specialist FRP manufacturers and deliver it as part of the project steel package: the panels are cut to the platform layout, fitted to the platforms and walkways we fabricate, checked, labelled and packed with the steel. The client gets one coordinated supply and one set of drawings instead of two separate packages that have to be matched on site.

Types and options

There are two families of FRP grating, and the choice mainly depends on span, load and how the panels must be cut.

• Resins: isophthalic polyester for general use; vinyl ester for aggressive chemicals; phenolic where low smoke and better fire behaviour are required. The resin choice is made with the manufacturer's chemical resistance guide.
• Surfaces: grit-bonded top for wet and oily floors, or concave (meniscus) top for a lighter, easier-to-clean surface.
• Colours: typically grey, yellow or green, pigmented through the resin.
• Depths: typically 25–50 mm, chosen by span and load from the manufacturer's tables.

Design and compliance

Loads and deflection for FRP grating come from the manufacturer's published load–span tables, not from steel rules: FRP is far less stiff than steel, so deflection, not strength, usually governs the span. World Steel selects the depth and type against the specified uniform and concentrated loads and a deflection limit agreed with the engineer, and lays out the support steel to suit.

Access geometry is the same as for steel floors – walkway widths, guardrails and toe boards to OSHA 29 CFR 1910, AS 1657 or EN ISO 14122-2. Fire performance depends on the resin and the specific product. Where a project calls for a flame spread rating (for example ASTM E84 in the US), a reaction-to-fire class (EN 13501-1) or Australian early fire hazard indices (AS 1530.3), the evidence must be the manufacturer's own test report for that product; World Steel does not test or certify FRP and passes the manufacturer's documents on unchanged.

FRP grating is non-conductive and non-magnetic, which is why it is chosen around electrical equipment and in some rail and instrumentation areas. Confirm any electrical property with the manufacturer's data.

Supply, fitting and packing by World Steel

We receive the platform layout or IFC model, prepare a panel layout in Tekla with the support steel, and order the panels from the FRP manufacturer to suit. Panels are cut with diamond or carbide tools to the layout, and every cut edge is sealed with compatible resin so that glass fibres are not exposed to chemicals or moisture. Openings for pipes and columns are cut and banded where the layout requires it.

The supporting steel – beams, angles, trimmers and hold-down clips – is fabricated in our plant and finished by hot-dip galvanising or stainless steel where the environment demands it. Panels are trial-fitted where specified, marked with their layout numbers, and packed on pallets protected from UV and abrasion for export shipping alongside the steel.

Installation and selecting

• Fix panels with stainless steel M-clips or saddle clips at the spacing the manufacturer recommends – never by welding or by drilling large holes through bearing bars.
• Keep a small gap between panels and to fixed steel for thermal movement.
• Seal any site cuts immediately with the resin kit supplied.
• Specify the type, resin, surface, colour, loads, deflection limit and fire requirement; see FRP stair treads and FRP handrail for the matching items.