Published by pultrx, the export trading company of Henan Zhongsheng. This is a buyer planning guide; the manufacturer confirms project specifications in writing.
The short answer
Switch from steel to FRP grating where galvanizing would be consumed by the environment, where the floor sits near live electrical equipment, or where panels must be handled without a crane. Keep steel bar grating where the floor carries vehicles or heavy wheel loads, spans far between supports at a limited depth, sits near hot surfaces or open flame, or must meet a fire rating that the project will not demonstrate for FRP.
FRP grating is a strong candidate
- Wastewater and water treatment walkways, channel covers and launder covers
- Chemical plants, plating, pickling and battery rooms
- Offshore platforms, ships, docks, cooling towers and other salt or spray zones
- Substations, rail and cable trenches where a nonconductive floor is required
- Rooftop and mezzanine access where panels must be lifted by hand
Steel grating usually stays
- Floors for forklifts, trucks and other wheel loads
- Long clear spans where a deeper FRP panel will not fit
- Areas near furnaces, hot lines, flares and welding work
- Escape routes or platforms with a fire rating the FRP option cannot document
- Locations with heavy impact from dropped steel parts or tools
FRP grating vs steel grating: comparison
| Property | FRP grating | Galvanized steel bar grating |
|---|---|---|
| Corrosion protection | Resin through the whole section; resin type chosen for the media | Zinc coating (ASTM A123); cut edges and welds need repair |
| Stiffness and span | Lower stiffness; deflection usually governs the span | Higher stiffness; longer spans at the same depth |
| Weight | A fraction of steel; most panels can be lifted by hand | Heavier; lifting equipment often needed |
| Electrical | Nonconductive | Conductive; must be bonded where required |
| Fire | Depends on resin; fire-retardant and phenolic grades exist | Noncombustible |
| Heat | Resin softens as it approaches its glass transition temperature | Unaffected at normal process temperatures |
| Surface | Molded-in meniscus or grit top; color through the panel | Serrated or plain bars; painted or galvanized finish |
| Cutting and openings | Cut with diamond or carbide tools; seal cut edges with resin | Cut and welded; repair galvanizing at cuts |
| Fixing | Hold-down clips to the support structure | Welded or clipped to the support structure |
Deflection: the check that changes when you switch
A steel grating specification typically states a design load, such as 100 psf uniform or a 300 lbf concentrated load on floors, and limits deflection to L/240 or 1/4 inch, whichever is less. Steel bar grating usually meets that limit with room to spare. FRP grating has lower stiffness, so deflection, not breaking strength, controls the span. Strongwell's selection guidance limits FRP grating deflection to about 1/4 inch (6 mm) for pedestrian comfort and advises against more than 1/2 inch (12 mm), because larger deflections pry on the hold-down clips and loosen fasteners.
In practice, a like-for-like depth swap may need extra supports or a deeper FRP panel. Send the support layout with clear spans, the load case and the deflection limit, and ask for a load table or calculation for the exact panel, depth and span offered. Do not compare load tables from different manufacturers as if they were interchangeable.
Molded or pultruded FRP grating?
Molded grating is a one-piece grid. It has high corrosion and impact resistance, a large open area and, in square mesh, two-way span, which makes it the usual replacement for steel grating in walkways and process areas. Pultruded grating assembles pultruded bearing bars with cross rods. It spans further in one direction and is the closer match where the steel grating was chosen for span. Both types are made by our factory; the right one depends on the span, the load and the openings in the layout.
Compare construction, bearing direction, mesh pitch and clear opening before choosing the FRP panel type. Molded vs pultruded grating: how to specify the right panel
Fire, heat and electrical safety
Steel grating does not burn. FRP grating does unless the resin is formulated for fire performance, and phenolic grating is used where fire, smoke and toxicity are the main concern. Fire classification is not a property of fiberglass in general. If the project requires, for example, a flame spread index under ASTM E84 or a European reaction-to-fire class, name the test and the class in the RFQ and ask for the report that covers the offered resin and panel. Set the maximum service temperature for areas near hot equipment.
FRP grating does not conduct electricity, which is why it is used in substations, cable trenches and around electrolytic cells. A nonconductive floor does not remove the need for the site's electrical safety rules. Where the project needs a defined dielectric value, state the test method and voltage.
Installation and life-cycle cost
Most FRP panels can be carried by one or two people and cut on site without hot-work permits, which shortens shutdowns in operating plants. Openings for pipes and equipment are cut and sealed with resin; edges around large openings may need banding or extra support. Panels are fixed with hold-down clips, typically stainless steel, at the spacing the supplier recommends.
A square meter of FRP grating can cost more than the same area of plain galvanized steel grating. The comparison changes once installation labor, lifting equipment, galvanizing repair, painting and replacement intervals in a corrosive area are counted. Build the comparison on the same layout and the same service period. pultrx does not publish grating prices; the quotation for your panel schedule is the price that applies.
Convert a steel grating schedule into an FRP grating RFQ
| What the steel schedule shows | What to send for FRP | Why it matters |
|---|---|---|
| Bar size and spacing, for example a steel bar grating designation | Clear spans, support layout, load case and deflection limit | FRP panel depth is set by deflection, not by the steel bar size |
| Span direction on the drawing | Bearing direction for every panel | Pultruded and rectangular molded grating span one way |
| Galvanized finish | Chemicals, concentration, temperature, indoor or outdoor | Decides the resin and any UV protection |
| Serrated surface | Required surface: meniscus, fine, medium or coarse grit | Grit size depends on footwear, oil and debris |
| Welded or clipped fixing | Support material and flange thickness for the clips | Clip type and spacing are quoted with the panels |
| Fire or electrical requirement | Test standard, class or dielectric value | Fire-retardant and phenolic grades are separate products |
| Panel list with cutouts | Panel sizes, cutouts, banding and quantities | Cutting and banding before shipment are quoted per panel |
Henan Zhongsheng, our factory in Xinxiang, makes molded and pultruded FRP grating and stair treads. pultrx, the factory's directly affiliated export trading company in Shanghai, quotes and exports them. The quotation names the panel type, depth, mesh, resin, surface, the load and fire data supplied with the order, and the inspection and packing terms.
Sources and further reading
- Vulcraft: Section 05530 metal gratings, standard specification
Guide specification for steel bar grating: 100 psf uniform or 300 lbf concentrated floor load, deflection limited to L/240 or 1/4 inch for walkways, hot-dip galvanizing to ASTM A123, welding to ANSI/NAAMM MBG 533.
- Strongwell: five tips for fiberglass FRP grating selection
States that serviceability, not strength, generally controls FRP design; deflection is usually limited to 1/4 inch (6 mm) for pedestrian comfort and more than 1/2 inch (12 mm) is not advisable because of prying on hold-down clips.
- Fibergrate: grating selection guide
Compares rectangular-mesh molded, square-mesh molded and pultruded grating for corrosion resistance, span, impact, open area and bidirectional span.
- Strongwell: molded and pultruded fiberglass grating construction
Construction difference between molded grids and assembled pultruded bearing bars. Ratings for named products do not qualify other manufacturers' grating.
Questions buyers ask
- Is FRP grating as strong as steel grating?
- FRP grating can carry pedestrian and light equipment loads, but it is less stiff than steel bar grating. At the same depth and span it deflects more, so the panel is usually chosen by the deflection limit. Ask for a load table or calculation for the exact panel and span.
- Can I replace steel grating with FRP grating of the same depth?
- Sometimes, on short spans. On longer spans the FRP panel may need to be deeper or need extra supports. Send the clear spans, load and deflection limit so the factory can propose a panel.
- Is fiberglass grating fire resistant?
- Only if the resin is formulated for it. Fire-retardant and phenolic grades exist; ask which resin the offered panel uses. Name the fire test and class your project requires and ask for the report covering the offered panel.
- How long does FRP grating last compared with galvanized steel?
- In corrosive service FRP grating does not lose section to rust, while galvanizing is consumed over time and needs repair. Service life depends on the resin, UV exposure, temperature and mechanical wear, so compare the two on the same environment and maintenance plan.
- What does GRP grating mean?
- GRP (glass reinforced plastic) grating is the UK name for FRP or fiberglass grating. Molded and pultruded GRP grating are the same product types described in this guide.
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