Box Sections

The figure shows the location of holes and clipped corners, which must be flush. Using the following formulas, the table shows typical sizes of holes.
Internal Gussets
- Space at minimum of 36 (91 cm)
Box Sections
- If H + W = 24 (61 cm) or larger, the area of the hole, plus clips, should equal 25% of the cross-sectional area of the box (Area = H x W).
- If H + W is between 16 and 24 (41-61 cm), the area of the hole, plus clips, should equal 30% of the cross-sectional area of the box.
- If H + W is between 8 and 16 (20-41 cm), the area of the hole, plus clips, should equal 40% of the cross-sectional area of the box.
- If H + W is less than 8 (20 cm), leave completely open, with no end-plate or internal gusset.
The table below is for square box-sections only. For rectangular sections, calculate the required area and check with the galvanizer for positioning of openings.
Box Size | Holes A-Dim (H + |
---|---|
48 (122 cm) | 8 (20 cm) |
36 (19 cm) | 6 (15 cm) |
32 (81.3 cm) | 6 (15 cm) |
28 (71 cm) | 6 (15 cm) |
24 (61 cm) | 5 (12.7 cm) |
20 (50.8 cm) | 4 (10.2 cm) |
16 (40.6 cm) | 4 (10.2 cm) |
12 (30.5 cm) | 3 ( 7.6 cm) |