1, the material 2, design problem and 3 application problems.

1, material: the main parts of the gantry scaffolding tube steel pipe. According to the standard requirements, the doors scaffold should use 48 mm outside diameter, wall thickness of 3.5 mm carbon steel pipe welding.

Many steel pipe manufacturers in order to rob market, would deliberately cut corners to reduce costs, the production of steel tube wall thickness is 3.0 mm to 3.2 mm, the weight on the 3.5 mm theory are still settled, in fact the weight of per ton steel tube is only 860-920 kg. Steel tube rental is according to the length of the charge, isn't charge by weight, so the lease unit are willing to buy this kind of 3.0 3.2 mm steel pipe.

This kind of steel pipe due to the thickness of the moment of inertia to make lose 10%, use the rust after a long time can cause wall thickness is thinner and moment of inertia will also reduce, so will become a safety hazard.

2, the design problem: activity scaffolding collapse is the main reason of the support is not stable. Before construction, many enterprises were not scaffolding stiffness checking, just rely on experience support system, the insufficient scaffolding tube rigidity and stability of the support system to consider. Other steel pipe due to corrosion or wear and tear, and the local bending, welding, will lead to the actual bearing capacity to reduce a lot of steel tube, it is easy to happen accident.

3, the application problem: many current construction site technical director, not on the safety of the construction workers for detailed technical clarificaiton, plus some workers quality is lower, will inevitably occur application problems.