What is galvanized trench cover grating?
Galvanized trench cover grating is standard trench cover grating that has been hot-dip galvanized: the finished panel is immersed in molten zinc so a coating forms over the whole surface, inside and out.
The key point is the sequence. The panel is fabricated first, then galvanized. If the steel were coated before cutting and welding, those cut edges and welds would be left bare.
Why galvanizing is done after fabrication
- Cut edges get covered: every trimmed edge is coated, not just the original bar surface.
- Weld points get covered: the joint areas are protected along with the bars.
- Internal gaps get covered: zinc reaches into the open grid and between bars.
- Sacrificial protection: if the coating is scratched, zinc corrodes in preference to the steel beneath.
Galvanizing sequence
Degreasing
Oil, grease and marking are removed so the surface is chemically clean.
Pickling
Mill scale and rust are removed in acid.
Fluxing
A flux layer prevents re-oxidation before the zinc bath.
Zinc bath
The panel is immersed in molten zinc and withdrawn at controlled speed.
Cooling
The coating is cooled and the panel handled to avoid damage.
Inspection
Coverage, appearance and drainage of excess zinc are checked.
Coating and service environment
- Coating thickness is set by the specification and the service environment; state the requirement in the enquiry.
- Thicker coating generally suits more aggressive or consistently wet conditions.
- Do not convert coating thickness into a promised service life—actual life depends on the site.
- In strongly corrosive drainage, consider stainless steel instead of coated carbon steel.
Cut edges, welds and touch-up
- Field cuts and drilled holes expose bare steel; treat them on site.
- Use a zinc-rich paint for touch-up on galvanized work.
- Do not weld or grind after galvanizing without planning the repair.
- Remove zinc runs or sharp spikes that could catch or injure before installation.
Handling and installation cautions
- Handle with slings or soft slings; dragging abrades the coating.
- Do not stack wet panels tightly—keep them able to dry to avoid wet-storage staining.
- Allow for coating thickness when setting frames, clips and clearances.
- Keep coated panels away from direct contact with dissimilar metals where possible.
Ordering information
- Opening width, length and clear span
- Bearing-bar size, pitch and surface type
- Frame, fixing and access requirement
- Coating specification or service environment
- Quantity, destination and required date
Galvanized Trench Cover Grating FAQ
Is the grating galvanized before or after it is made?
After. Fabrication first, then hot-dip galvanizing, so cut edges and welds are coated.
What if I cut the panel on site?
Treat the exposed edge with a zinc-rich paint to restore protection.
Can I get stainless instead?
Yes, for aggressive or consistently wet drainage environments.
