Choosing and specifying steel gratings for plant platforms

Steel gratings form the floor of most industrial platforms, stair treads, walkways and trench covers. They let light, air, and liquids pass through and give grip underfoot. A grating that is too light for its span will deflect and feel unsafe, so specification is worth getting right.

Types of grating

Welded bar grating, also called pressure-welded or forge-welded grating, is the most common type for plants. Bearing bars run in the span direction and cross bars are resistance-welded at right angles into the bearing bars under pressure. Press-locked grating has cross bars pressed into notches in the bearing bars. Riveted grating uses a swaged cross rod. Welded bar grating is the common industrial choice because of its strength and rigidity. In North America the relevant specifications are the NAAMM standards ANSI/NAAMM MBG 531 for metal bar grating and MBG 532 for heavy duty metal bar grating, and Indian buyers typically refer to these or to the project specification.

Key specification items

Bearing bar size and pitch

The bearing bars carry the load, so their depth and thickness decide how much span the panel can handle. Deeper bars handle longer spans and heavier loads. A pitch of about 30 mm between bearing bars is a very common spacing, and closer spacing is used where small objects or heels may fall through. The cross bar pitch, commonly about 100 mm, controls panel rigidity and the opening size.

Span, load and deflection

State the clear span between supports, the uniform live load and any concentrated or wheel loads. The manufacturer provides load tables that give the allowable load and deflection for each bar size at each span. Do not guess. For platforms people walk on, the project specification normally sets maximum deflection, and for forklift or vehicle areas you need heavy-duty grating.

Surface type

A plain top bar is smooth. A serrated top has teeth cut into the bars to give better slip resistance, and it is advised for outdoor platforms, oily areas, ramps and stairs.

Material and finish

Hot-dip galvanizing is carried out after fabrication, to standards such as IS 2629 or ASTM A123. Specify the coating requirement, and remember that galvanized panels cannot be welded or cut on site without repairing the coating.

Details that avoid site problems

• Give panel sizes and layout drawings with cut-outs for pipes, columns and ladders
• Specify banding on cut edges and openings so cut bars are closed and cannot be a trip hazard
• Choose the fixing: saddle clips, welded clips or bolted clamps, with enough per panel
• Provide toe plates and handrail details, which are normally separate items
• Keep bearing bars running in the span direction and support each panel on all bearing ends

Safety and maintenance

Inspect gratings periodically for corrosion at the bearing bar ends, loose fixings and damaged edges. Replace corroded or bent panels rather than patching them, and make sure every opening cut after installation has a proper edge band and support.

Send us your platform drawing, spans, loads and finish preference, and we will quote grating panels, treads and accessories.