FRP Trench Drain Grates and Channel Covers
A drainage grate in a chemical plant is constantly wet and constantly attacked, which is why FRP covers outlast galvanized ones there - and they can be lifted out by one person for cleaning. A trench grate is a load-bearing lid over a channel, so it has to satisfy two conflicting demands: enough open area to take the water, and enough bar depth to take the wheel.
FRP grating for trench drain
Molded fiberglass grating is made from glass rovings in a thermoset resin - isophthalic polyester as standard, vinyl ester for strong acids and solvents. It never rusts, needs no coating and is roughly a quarter of the weight of a steel panel of the same size. The trade-off is stiffness: FRP deflects about four times as much as steel for the same depth, so supports are set closer (600-900 mm) and panels are thicker for the same load.
Surfaces are available smooth, concave (gritted) or with a gritted top layer for ramps and wet areas. Fixings are stainless or FRP clips, and panels are cut with a masonry blade on site.
Selection notes for this application
Pedestrian and light vehicle areas need a 25x3 or 30x5 bar with 30 mm clear openings. Car parks and yard drainage move up to 40x5. Truck routes, loading bays and container yards need 50x5 or heavier with cross bars at 50 mm, and the frame must be bedded in concrete rather than fixed to a plastic channel.
- Panel depth and support spacing set by FRP grating
- Surface: serrated or gritted where wet or oily
- Fixings isolated from dissimilar metals
- Cut edges sealed, passivated or galvanized on site
Typical specifications
| Panel | Mesh | Load (span 900 mm) | Weight | Typical use |
|---|---|---|---|---|
| 25 mm | 38x38 | 3.0 kN/m2 | 12 kg/m2 | Walkway, light platform |
| 30 mm | 38x38 | 5.0 kN/m2 | 16 kg/m2 | Platform, stair tread |
| 38 mm | 38x38 | 7.5 kN/m2 | 20 kg/m2 | Heavy walkway, vehicle light |
| 50 mm | 50x50 | 10 kN/m2 | 28 kg/m2 | Trench cover, heavy duty |
Related products and applications
Frequently asked questions
How long does FRP grating last?
20-30 years in most chemical and marine environments. It does not corrode, but UV exposure yellows the resin and reduces surface gloss, so an UV inhibitor is added for outdoor use.
Is FRP grating as strong as steel?
It has roughly a quarter of the modulus of steel, so it deflects more for the same depth. In practice a 38 mm FRP panel replaces a 25-30 mm steel panel for pedestrian loads, and supports are set closer.
Not sure which profile suits your site? Send the span, load and environment to our engineers and we will return a specification with drawings within one working day. Contact us or see the full product range.