Steel Grating Types Explained: From Bar Grating to Press Locked

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The difference between steel grating types depends on how the crossbars are attached to the load carrying bars, either through welding, press lock, swage lock, riveting and dovetail construction method. The method used determines the load bearing ability, surface and cost of production of the panels. Expanded metal, plank and compound grating are used for lighter applications or closed surfaces.

What Is Steel Grating?

Steel grating is an open grid system of load-carrying bars interconnected with cross bars in order to create a load-carrying and well-ventilated system. Steel grating is used for supporting loads such as people, tools, and equipment while providing the passage of air, light, water, and any other loose materials due to their perforation. Such properties allow its application in industrial floor systems, walkway systems, stair treads, drainage systems, and trench cover systems. Main parts of steel grating are load-bearing bars and cross bars. The bearing bars support the major part of applied loads while cross bars define spacing between bars.

Types of Steel Grating

Type	How Cross Bars Are Fixed	Load Capacity	Surface	Typical Use
Welded (forge-welded)	Welded to the bearing bars at every intersection	Highest	Rigid, robust	Industrial platforms, heavy walkways
Press-locked	Cross bars pressed into notched bearing bars	Light to medium	Neat, uniform	Architectural and commercial flooring
Swage-locked	Cross bars passed through punched holes and deformed	Light to medium	Smooth	Walkways, light platforms
Riveted	Rivets	Light	Mechanically fastened	Aluminium or stainless light-duty panels
Dovetail	Cross bars dovetailed into notches	Light	Small openings	Pedestrian areas

Bar Grating Types by Manufacturing Method

Bar grating is the type of grating based on the way the cross bars are connected to the bearing bars. All methods are mechanical joints with hot dip galvanized (if stated) as a separate joint coating process.

Welded (forge-welded) grating

At each corner, cross bars are welded to the bearing bars and the panel is therefore a single rigid grid. Hence, it provides high strength and it is the most chosen option for the heavy loadings and walkways in the industrial platforms. In corrosive environments, or when exposed to the outside air, welded panels are typically galvanized after they are welded.

Press locked grating

Pressure locked (press locked) grating is essentially press locked, the bearing bars have notches and the cross bars are pressed into the notches, which is basically a cold deformation joint so that the joint is locked. The outcome is a neat, even appearance and it's suitable for larger bar spacings. It is suitable for architectural, decorative and light to medium duty applications.

Swage locked grating

Swage locked grating is punched with holes in the bearing bars. Cross bars go through the holes and are swaged, or physically hammered, to hold the holes in place. It is a cold joint that is not welded. Panels have smooth upper surface and joint is not prone to loosen, suitable for walkways and light to medium duty use.

Riveted grating

The bearing bars are fitted with cross bars that are then riveted on. This method is normally used on aluminium or stainless steel panels where welding could be difficult or cause damage to the corrosion protective surface. It is used in light-weight and corrosive applications.

Dovetail grating

The ends of the cross bars are dovetailed into notches in the bearing bars. This creates tight, small openings and a close fit and is used for pedestrian use and when narrow openings are required.

For heavy loads, use welded panels if you are needing a rigid panel. If appearance and wider bar spacing are more important than load, then pressed locked or swage locked are common options. Double check method and load table with supplier.

Plain vs Serrated Grating

Bar grating can be supplied with a plain (smooth) top edge or a serrated one. Serrated grating has teeth or notches cut along the top of the bearing bars to improve grip. I-bar grating is a bearing bar profile with a wider top flange, sometimes used for a flatter walking surface. Choose serrated wherever the surface can become wet, oily or icy.

Feature	Plain (Smooth) Bar	Serrated Bar
Top edge of bearing bar	Flat, smooth	Notched or teeth cut along the top
Slip resistance	Standard	Better in wet, oily or icy conditions
Comfort for foot traffic	Smoother	Slightly rougher
Typical use	Dry indoor walkways, public areas	Oil and gas, food processing, outdoor and wet platforms, stair treads
Cost	Lower	Slightly higher (extra machining)

Steel Grating Materials

Material choice depends on the environment more than the load. Carbon steel is the default, and stainless steel grating is chosen when zinc coating is not enough. For help with the metals themselves, see carbon steel vs stainless steel, 304 vs 316 stainless steel and aluminium vs stainless steel.

Material	Corrosion Resistance	Strength / Weight	Best For	Watch Out
Carbon steel, hot-dip galvanized	Good with zinc coating (ASTM A123, or EN ISO 1461 outside the US)	High strength, heavier	General industrial platforms	Coating damage at cuts; galvanizing can distort wide-spaced grating
Stainless steel 304	Very good in most environments	High strength	Food, pharma, mild chemicals	Cost; chlorides
Stainless steel 316	Better in chlorides and marine	High strength	Marine, offshore, chemical	Higher cost
Aluminium	Good, no rust	Light, lower strength	Where weight matters	Lower load capacity
Fibreglass (FRP)	Excellent chemical resistance	Light, non-conductive	Chemical plants, electrical areas	Not steel; lower stiffness and fire/UV limits

Cut ends and drilled holes in galvanized grating expose bare steel, so touch them up with a zinc-rich coating after fabrication.

Steel Grating vs Fibreglass (FRP) Grating

Fibreglass grating (also called fiberglass or FRP grating) is a non-metal alternative made from glass fibre in a resin matrix. It is not steel, but buyers often compare the two.

Factor	Steel Grating	Fibreglass (FRP) Grating
Strength and stiffness	Higher	Lower stiffness; more deflection at the same span
Chemical resistance	Depends on coating or grade	Excellent in many chemicals
Weight	Heavier	Light and easy to handle
Electrical conductivity	Conductive	Non-conductive
Fire and UV	Better fire performance	Resin limits; UV stabilisation needed
Typical use	Heavy-duty industrial platforms	Chemical plants, electrical areas

Choose steel for heavy loads and higher temperatures. Choose FRP where chemical attack or electrical safety outweighs stiffness.

How to Choose Floor Grating Types for Industrial Use

Work through these points before asking for a quote.

1. Span and load. Note the clear span, the uniform load, any point or wheel load and the allowed deflection. Grating is specified from a load table, not from a general class.
2. Bearing bar size and pitch. Taller or thicker bearing bars carry more load. Closer pitch reduces the opening size.
3. Locking method. Welded for heavy duty, press locked or swage locked for lighter duty and appearance.
4. Surface. Plain for dry areas, serrated where the surface can be wet, oily or icy.
5. Opening size. Check that the openings suit the traffic, including small tools and heels.
6. Environment and corrosion. Pick galvanized carbon steel, 304 or 316 stainless, aluminium or FRP for the chemicals and humidity present. See corrosion-resistant plates.
7. Budget. Compare cost over the life of the installation, including coating maintenance.

Not sure which bar size and pitch to specify? Send the span, load and finish to our technical team and we will point you to the right load table.

Applications of Steel Grating

• Platforms and mezzanines: welded bar grating on a steel frame lets light and air through and reduces dust build-up.
• Walkways and catwalks: serrated panels give grip in wet or oily areas.
• Stair treads: serrated bar grating or plank grating with a nosing for grip.
• Trench and drain covers: grating covers channels while letting water in. Drain grates follow EN 1433 (which replaced DIN 19580), not platform load tables.
• Vehicle areas: heavy-duty grating specified to MBG 532 or the manufacturer's heavy-duty tables.
• Process plants and offshore: galvanized or stainless grating for corrosive or marine environments.