Something You Need to Know about Steel Grating Plate

Design Requirements for Steel Grating Plate

The design requirements for steel grating plates are as follows:

1. Stairs should prioritize safety and economy. Economic considerations include cost and space utilization. The step height of stairs is generally between 180mm and 200mm. Only in public places, the step height may be between 130mm and 160mm. The tread depth, which refers to the horizontal distance between consecutive steps, is typically between 230mm and 250mm, with a minimum of 220mm. A tread depth of 300mm would make it difficult to ascend the stairs comfortably.

2. When using spiral stairs, it is necessary to ensure that the tread plates meet the requirement of a minimum width of 0.22m at a distance of 0.25m from the inner handrail or the wall. This requirement is clearly defined in fire safety standards.

3. The selection of tread width is generally 800mm for stairs, but it can be increased if there is sufficient space.

Considerations for Steel Grating Plate Installation:

1. The net width of the stair platform should not be less than the width of the flight of stairs and should not be less than 1.10m.

2. The height of the stair handrail (measured from the front edge of the step) should not be less than 0.90m. For outdoor stairs, the handrail height should not be less than 1.05m.

3. When the width of the stairwell is greater than 0.20m, the clearance between the vertical bars of the handrail should not exceed 0.11m to prevent children from falling through.

4. The width of the flight of stairs is explicitly regulated in residential designs to meet fire safety requirements. In public buildings, the width of performance stairs is generally larger. However, special attention should be given to the relationship between handrail placement and the width of the flight of stairs. At least one side of the stairs should have a handrail, and when the net width of the flight of stairs reaches the capacity for three people, handrails should be installed on both sides. For a capacity of four people, a central handrail should be added.

Welding Techniques for Steel Grating Plate

Galvanized steel grating plates can be welded using methods such as manual arc welding, shielded metal arc welding, gas tungsten arc welding, and resistance welding.

Manual Arc Welding:

Weld preparation

To reduce welding fumes, prevent cracking, and avoid the formation of pores, the zinc layer near the groove should be removed before welding. This can be done through flame heating or sandblasting. The groove clearance should be controlled within 1.5-2mm, and for thicker workpieces, it can be relaxed to 2.5-3mm.

Electrode selection

The principle for electrode selection is to ensure that the mechanical properties of the weld metal are as close as possible to the base metal, and the silicon content in the deposited metal should be controlled below 0.2%. Welding with rutile, titanium oxide, cellulose, titanium calcium, or low hydrogen electrodes can achieve satisfactory joint strength. For low-carbon galvanized steel grating plates, J421/J422 or J423 electrodes should be preferred. Short arc length should be used during welding to prevent excessive melting of the galvanized coating, ensuring the corrosion resistance of the workpiece and reducing fume generation.

Shielded Metal Arc Welding (Gas Metal Arc Welding):

Welding using CO2 shielding gas or mixed gases such as Ar CO2 or Ar O2. The choice of shielding gas has a significant impact on the zinc content in the weld. Using pure CO2 or CO2 O2 results in higher zinc content, while using Ar CO2 or Ar O2 results in lower zinc content. The current has minimal influence on the zinc content in the weld. With increasing welding current, the zinc content in the weld slightly decreases. When welding galvanized steel grating plates using gas shielding, the amount of welding fumes is much higher compared to manual arc welding. Therefore, special attention should be paid to ventilation. The amount and composition of fumes are primarily influenced by the current and shielding gas. Higher currents or higher concentrations of CO2 or O2 in the shielding gas result in increased fume generation and higher ZnO content, which can reach around 70% at maximum. Under the same welding specifications, the depth of fusion is larger for galvanized steel grating plates compared to non-galvanized ones.

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