The load table is for the 30 x 30 mm mesh and a working load shown as kg/m2, approximately. For foot traffic, the working load applied should be x = 500 kg/m2, as shown in the stepped part of the table. This is not applicable to concentrated pressure, such as car, truck or forklift traffic, etc. Grating for this type of traffic is made using different types of mesh, with bars of thicknesses ranging between 4 and 10 mm.
WHAT IS A GRATING?
Basic information for defining manufacture: There are three basic elements that make up grating: the bearing bars, crossbars and the banding.
1. Bearing bar (Fig. 1–A) This is the bar that supports the load on the grating and must therefore be supported at its ends. (Fig. 1).
Depending on the weight to be supported and the distance between supports, the bearing bar must be calculated to increase height and thickness.
However, for large loads and vehicle traffic, grating can be manufactured with bearing bars of up to 100 mm in height and 10 mm in thickness (Fig. 2-h,e)
2. Crossbar (Fig. 1–B) As the name indicates, this is the bar that crosses and joins the bearing bars.
For this reason, its load-bearing function is practically nil.
Different separators are used: flat bar 10 mm in height, with the same thickness as the bearing bar, smooth round bar and twisted round bar in different thicknesses.
3. Banding Essential for preventing the bearing bars and crossbars from moving and losing their shape
WHAT IS THE MESH?
Regardless of the manufacturing system, different types of grating are determined by the mesh.
The mesh is the distance between bearing bars and crossbars.
Technically the measurement is always taken between the bars, ignoring their thickness, although, in general, this is rounded up or down commercially.
The mesh nomenclature always uses two groups of numbers separated by an x: the first figure indicates the distance between the bearing bars and the second figure indicates the distance between the crossbars (Fig. 2).