Galvanised steel drainage grates & frames

What they are

Steel drainage grates are welded bar grates – flat bearing bars held by cross bars or twisted rods – seated in a steel angle frame that is cast into the concrete of a pit, trench or kerb inlet. The grate lets stormwater in, keeps people, wheels and debris out and transfers the traffic load to the frame and the surrounding concrete. Because every part is plain carbon steel, the whole assembly can be designed to the opening, cut to size, welded and hot-dip galvanised as one coordinated package.

World Steel fabricates grates and frames in its plant at Hai Son Industrial Park, Tay Ninh, alongside the steel bar grating and trench covers it already supplies for industrial floors. Square and rectangular grates for stormwater pits sit naturally with our pit covers, and heavier traffic areas move up to heavy-duty road grates.

Types and load classes

The load class sets the bearing bar depth, bar spacing, frame angle and anchorage. It is chosen by the designer from the location of the pit – not by the fabricator – and the table below shows the range this product covers. For classes E to G, see the heavy-duty page.

• Pit grates – square or rectangular grates in a four-sided angle frame for side-entry and grated stormwater pits.
• Trench and channel grates – long modules in a continuous seat frame for surface drains along driveways, loading aprons and hardstands.
• Bicycle-safe grates – bearing bars run across the direction of travel, or slot width is limited to the road authority rule, so cycle wheels cannot drop in.
• Heel-guard grates – close bar spacing or a fine-mesh pattern for plazas and public footpaths.
• Hinged and lockable grates – a hinge on one side and a bolt or lock on the other for theft resistance and easy maintenance access.

Design and compliance

In Australia access covers and grates are specified to AS 3996-2019, which defines classes A to G by test load and sets requirements for seating, fit and marking. In Europe the equivalent is the EN 124 series (A15 to F900), and in the US road-trafficked grates are usually designed for AASHTO H-20 / HS-20 wheel loads. World Steel checks bearing bar depth and spacing, frame angle size and weld sizes against the class specified, using the project design or the client's standard drawing. Where a load test or a product approval is required, it is product-specific and is agreed and witnessed as part of the contract; we do not claim approvals that have not been granted for a specific design.

Frames are anchored with welded lugs or studs to suit the concrete detail, checked to AS 5216, EN 1992-4 or ACI 318 Chapter 17 as applicable. Welding is to AS/NZS 1554.1, AWS D1.1 or EN ISO 3834-2 procedures, and hot-dip galvanising is by qualified galvanisers to AS/NZS 4680, ASTM A123 or EN ISO 1461. Design for galvanising – vent holes, drained corners, no closed pockets – follows AS/NZS 2312.2.

Fabrication and finishing at World Steel

Flat bar and angle are cut on CNC lines, notched and assembled in jigs so every grate drops into its frame with an even, rattle-free seat. Bearing bars are welded to the cross bars and edge bars, frames are mitre-welded and anchor lugs are added to the shop drawing. Each grate and frame pair is trial-fitted, marked with its pit reference and load class, then sent for galvanising as a set. After galvanising the fit is checked again, bolts are fitted and pairs are packed together on export pallets. Shop drawings and an IFC model are prepared in Tekla, and production follows our steel grating process.

Installation and site notes

• Brace the frame to hold the clear opening, set it to finished level and fully compact concrete under the seat flange.
• Keep the grate in the frame during the pour so the frame cannot rack; clean the seat after curing.
• Fit bolt-down or locking hardware where traffic or theft is a risk; check hinged grates open freely.
• Repair any zinc damage from handling with zinc-rich paint per AS/NZS 4680 / ASTM A780. See foundation interfaces for cast-in coordination.

Selecting and specifying

To size a grate we need the clear opening, the load class from the drawings, the bar orientation relative to traffic, any bicycle-safe or heel-guard requirement and the locking method. For large civil packages we can schedule grates by pit number so that they arrive grouped for each road section. Export packing and container loading are handled by our export supply team.