Material Comparison

FRP grating vs steel grating

FRP grating weighs about half as much as galvanized steel bar grating (14–22 kg/m² for 38 mm molded FRP against 34–48 kg/m² for 25 mm steel bar), does not rust and does not conduct electricity. Galvanized steel costs less per square meter and carries higher concentrated wheel loads (90–180 kN against 45–90 kN for pultruded FRP). FRP pays off where corrosion, wet footing or electrical safety drive the choice; steel remains the usual choice for dry areas with heavy vehicles.

Last updated Sep 27, 2026

In corrosive, electrical or wet areas, FRP gratings avoid the recoating cycle that limits galvanized steel

Steel bar gratings dominate industrial walkways for one reason: low material cost. In dry, non-corrosive, non-electrical environments with heavy vehicle traffic, that cost advantage wins. Everywhere else (chemical plants, wastewater, offshore platforms, coastal marinas, substations, food processing with wash-down) galvanized steel enters a 10–15 year recoating cycle that erases its initial savings. Pultruded and molded FRP gratings remove that cycle and add a gritted walking surface, lower installed weight and electrical insulation.

This page compares the two on the properties that matter to grating specifiers: uniform and concentrated load capacity, corrosion, wet slip resistance, fire, electrical conductivity and lifecycle cost.

Side-by-side: FRP vs hot-dip galvanized steel gratings

FRP values reflect pultruded and molded E-glass/polyester gratings typical of F1 Composite product range. Steel values reflect standard bar grating, 25mm × 5mm bearing bars, hot-dip galvanized per ASTM A123. Bold marks the properties where FRP materially outperforms steel.

Property	Unit	Pultruded or molded FRP	Hot-dip galvanized steel
Weight (installed)	kg/m²	14 – 22 (38 mm molded)	34 – 48 (25 mm bar)
Load capacity (30 mm deep)	kN/m² UDL	≥ 500	≥ 500
Concentrated load (wheel)	kN	45 – 90 (pultruded)	90 – 180
Corrosion resistance	—	Resists acids, alkalis, chlorides and salt water (resin-dependent)	Coating-dependent; galvanizing can fail in 10–15 years in aggressive service
Electrical conductivity	—	Non-conductive (insulator)	Fully conductive (fault current path)
Slip resistance (wet)	PTV	High with a grit top; report on request	25 – 40 (serrated)
Fire	—	ASTM E84 Class 1 with FR resin; report on request	Non-combustible
Installation tools	—	Standard hand tools, no hot work permit	Cutting torch, welding, grinding
Recoating (coastal / industrial)	—	None; life depends on resin and UV exposure	Often every 10 – 15 years
Spark risk	—	No impact sparks; assess static risk in ATEX zones	Sparks on impact
Magnetic interference	—	Non-magnetic	Ferromagnetic
Thermal conductivity	W/m·K	0.3 – 0.5	50

Five environments where FRP often replaces steel

Wastewater treatment plants. H₂S, chlorine and constant humidity can corrode galvanized steel gratings within a decade. Vinyl ester FRP grating does not rust and needs no recoating in the same service, which is why many water utilities now specify it for treatment works.
Offshore platforms and coastal marinas. Salt water and salt spray pit galvanized coatings, and stainless steel grating costs considerably more than FRP. Offshore operators widely use FRP gratings for secondary walkways, helideck surrounds and engine-room access platforms.
Electrical substations and power plants. A non-conductive FRP grating carries no fault current, which reduces touch and step potential hazards around equipment. Metal supports and fixings still follow the grounding design.
Chemical and pulp & paper plants. Sulfuric acid, sodium hydroxide, hypochlorite, and solvent exposure attack any steel coating. FRP vinyl ester gratings resist the full range of process chemicals per the chemical resistance chart, which is why process plants routinely replace steel mezzanines and walkways with FRP during turnarounds.
Food and pharmaceutical facilities. Food-contact resins where specified, sealed non-porous surfaces and cleanability with caustic CIP solutions make FRP a good choice for environments where steel corrosion particulates could contaminate product.

Heavy vehicle traffic in dry, non-corrosive environments

Steel bar gratings remain the right specification in three scenarios. Heavy wheel loads: forklifts above 45 kN per wheel and truck traffic on loading docks still benefit from steel's higher concentrated-load capacity. Dry industrial buildings: indoor steel mills, dry warehouses, and foundries with low humidity and no chemical exposure see galvanized steel last 40+ years without recoating, eliminating FRP's lifecycle advantage. Fire-critical primary structures: where code requires non-combustible structural elements, steel is the direct choice; FRP with FR resin can reach ASTM E84 Class 1 flame spread but is not non-combustible.

Frequently asked questions

Can FRP gratings carry the same loads as steel bar gratings?

For uniform distributed loads up to 500 kN/m², FRP molded and pultruded gratings match standard steel bar gratings at comparable depths. For concentrated wheel loads above 90 kN, steel still leads: heavy forklifts and vehicle traffic may require either deeper FRP sections or hybrid FRP-over-steel panels. For pedestrian walkways, platforms, maintenance access, and light vehicle traffic (<45 kN wheel load), FRP is fully equivalent and often lighter-installed.

Why do industrial facilities specify FRP over hot-dip galvanized steel?

Hot-dip galvanized steel typically survives 20–30 years in benign atmospheres but fails in 10–15 years under acid rain, coastal salt, chlorine, H₂S, or wash-down chemicals. Every recoating cycle costs money and disrupts operations. FRP is immune to the electrochemical corrosion that attacks steel, so there is no coating to fail and no recoating cycle. In water treatment, pulp and paper, chemical process and coastal offshore applications, FRP often costs less than galvanized steel over the life of the walkway once recoating and downtime are counted.

Are FRP gratings safe around electrical equipment?

FRP gratings are electrical insulators. This is a safety advantage that steel gratings cannot offer. In substations, near transformers, or on electrified rail platforms, a metallic grating creates touch potential and step potential hazards during fault events. An FRP grating does not carry fault current, so it does not create these hazards itself. Metal supports, clips and fixings still need bonding as the grounding design requires.

How does slip resistance compare in wet conditions?

UK HSE guidance treats a Pendulum Test Value (PTV) of 36 or more as low slip risk on wet surfaces. FRP gratings with a factory-applied grit top are made for that wet service; ask for the slip test report for the surface you specify. Serrated steel bar gratings typically test at PTV 25–40 when wet, and smooth steel plate lower. For offshore platforms, wastewater plants and any walkway exposed to rain or process water, a gritted FRP surface gives better footing.

Is FRP cost-competitive with steel on initial installed cost?

Per square meter of grating material, hot-dip galvanized steel is typically 30–50% less expensive than pultruded FRP. However, installed cost (including supporting structure, lifting equipment, hot-work permits, and labor) is often comparable because FRP weighs 60% less. A two-person crew can install FRP gratings with hand tools where steel requires a crane, welding rig, and permit. Installed costs for chemical plant walkways are often close. Over the service life, FRP often costs less in corrosive areas once recoating and downtime are counted.

What grating types does F1 Composite manufacture?

F1 Composite supplies both pultruded and molded FRP gratings. Pultruded gratings (38mm, 50mm depths) suit heavy-duty walkways and vehicle traffic. Molded gratings (25mm, 38mm, 50mm) with square-mesh 38×38mm or 50×50mm patterns suit platforms, mezzanines, stair treads, and trench covers. Solid-top, ventilated, and anti-slip grit surface finishes are all available. Standard resin is isophthalic polyester; vinyl ester is offered for aggressive chemical service.