FRP Grating Load Capacity, Span and Selection Guide

author：Jinyang time：2026-07-06 00:00:00 Click：187

FRP (Fiberglass Reinforced Plastic) molded and pultruded gratings are widely used in offshore platforms, chemical plants, walkways, stair treads and trench covers because they do not rust, do not conduct, and require almost no maintenance. However, many projects fail not because the grating is poor quality, but because the span or bar size is over-specified or under-specified. This guide explains how load capacity, span and resin type interact, and how to select the right grating for a given floor.

How FRP Grating Is Loaded

FRP gratings carry load as a series of parallel bars. The allowable span depends on two limits: bending stress (the grating must not break) and deflection (the grating must not sag more than a comfortable limit, typically L/120 or L/180). Heavy-duty industrial walkways are usually designed for a uniform live load of 5 kN/m² or a point load of 3 kN; vehicle traffic requires much deeper bars and shorter spans.

Common Grating Types

Type	Bar Size	Typical Span	Typical Use
Molded Grating 38 mm	38×38 mm mesh	Up to 900 mm	General walkways, trench covers
Molded Grating 50 mm	50×50 mm mesh	Up to 1200 mm	Heavy industrial, platforms
Pultruded Grating	I / T bar 40-100 mm	Up to 2000 mm	Long span, vehicle access
Concave / Grit Surface	Same as above	Same	Wet, oily, anti-slip areas

Resin Selection for the Environment

Standard polyester grating is fine for atmospheric and freshwater service. For chemical plants, pick iso-polyester or vinyl ester; for coastal offshore use, choose UV-stabilized resin with a surface veil to prevent fiber bloom. Color is mostly cosmetic, but yellow and gray are standard; green and red are available as OEM options.

Installation Notes

Grating panels must be secured with non-slip clamps or FRP angle frames at every support, never welded directly to steel. Leave 3-5 mm expansion gap between panels. Cut edges must be sealed with resin to prevent edge wicking, which allows moisture and chemicals to travel into the cut fibers. For overhead walkways, add toe kicks and handrails to the design.

Comparison: FRP vs. Steel Grating

Metric	FRP Grating	Steel Grating
Weight	~1/4 of steel	Heavy
Corrosion	Excellent, no painting	Galvanize / paint needed
Conductivity	Non-conductive	Conductive
Maintenance	Almost none	Periodic painting
First Cost	Higher	Lower

Conclusion

Specifying FRP grating is a matter of matching bar depth to span, resin to environment, and surface finish to slip risk. Hebei Jinyang Environmental Protection Equipment Co., Ltd. supplies molded and pultruded FRP gratings with load calculation sheets and installation drawings for each project.