Is disc-buckled scaffold the safest scaffold at present? The answer must be yes. The premise is that the quality must meet the national standards and requirements. Although disc-buckled scaffold has been known for its high safety, high bearing capacity, high efficiency and time-saving, with the increasing demand year by year, there are more and more different manufacturers, however, be with the mixed quality.
A Viaduct Project in Guiyang has encountered quality problems, and a collapse accident occurred during the use of the disc-fastened high formwork. There are three main reasons for the scaffolding accidents: product quality problems, construction technology problems and illegal operation. The disc-buckled scaffold is welded on the column with way of cast steel or stamped discs. The cross bar is connected with the wheel disc on the column through the head of the cross bar and fixed by the bolt. Compared with traditional brackets such as bowl buckles and steel pipe fasteners, the disc buckle scaffold has the characteristics of high erection efficiency, good stability and high bearing capacity. Therefore, the welding of disc, cross bar and cable-stayed rod head of disc-buckled scaffold is very critical. The welding quality of each joint directly affects the safety of construction. In addition, the quality of screw nut is also very important.
The survey found that there are the following problems in the scaffolding materials used in a viaduct project in Guiyang:
1. False welding and rosin joints.
There are serious welding defects in the quality of the bracket, inadequate penetration and unqualified welding quality. The pulling of the cross rod plug causes the whole shedding and the connecting casing shedding under load.
2. Casting defects of plugs
It was found that the casting technology of coated sand was adopted for the cross rod and inclined rod plug of disc-buckled scaffold. Because the casting parts were small and the casting defects were obvious. Compared with the wax die casting process, the casting quality of plug is poor, and a lot of shrinkage holes, blowhole and slag inclusion defects are found on the broken castings. The load-bearing capacity of disc-buckled scaffold bracket is seriously restricted.
3. Welding Quality Defects of Wheel Disc Material
The collapsed high formwork support rod disc is made of Q235 material. The quality of welding seam between wheel disc and vertical pole is not up to the standard, which greatly weakens the connection strength of the joint.