... BS4592, AS1657, JS31011.3 Grating Dimension Load Bearing Flat Bar sizeThickness≥3mm, depth ≥19mm19X3, ... Grating type: flat bar: plain type, plain I type, serrated type, serrated I type; cross bar: round type and square twisted type. steel grating, bar grating, floor grating ... , stair treads, trench grating