And it shall be tied with the vertical pole to tighten the horizontal pole. The structure of square tube requires:

When the erection height exceeds 40m and there is wind vortex effect, the square tube structure shall comply with the following rules:

1. The longitudinal distance and step distance of vertical pole of single and double row square pipes shall not be greater than 2.1m, and horizontal diagonal bracing shall be set.

2. The degree frame must be set at the upper part of the top portal, the setting layer of wall connecting parts and the setting place of the protective shed of the portal type square steel tube.

3. The square bamboo tube shall be provided with a top strut, which shall not be removed during the use of the square bamboo tube.

4. A pair of scissors should be set up along the outside of the square tube to support the fragrant steamed buns, and a protective layer must be set under the scaffold board of the operation layer.

5. On the outside of the working layer, the horizontal distance of the upright shall not be greater than 1.6m.

6. Wall connecting pieces (or wall connecting rods) shall be used according to the regular distance to stop the connection with the building structure, and wall connecting measures against wind vortex overturning shall be set.

7. The scaffold board must be paved fully and stably according to the width of the square tube, and set up and removed synchronously with the square tube.

8. When the height of the double row fastener type square steel pipe exceeds 24m, the cost shall be reduced according to the structural requirements of the square pipe. The gap between the scaffold board and the wall shall not be greater than the structural requirements of the 200mm square pipe. Protective railings and toe boards shall be set according to the rules.

9. The square pipe shall be blocked by dense mesh safety vertical network according to the rules.