Many kinds of couplers are used in the construction projects to make sure the fixation and connection between tubes and ledges are     secured, such as the toe board coupler, used for fixing and tied to the toe boards.

• For the non-processing couplers, the surfaces shall be treated to be even and solid and the residue left on the pouring holes shall comply with the designing regulations.

• For the metallurgical medal couplers, the allowing height is 2-5mm and 5-15mm height for the black height.

      There shall be no cracks, penetration holes, cold shut, shrinkage porosity or slag inclusion.

• For the non-processing couplers, the burrs on the surface shall be treated to the same surface level of the couplers.

• The wall thickness of the scaffolding couplers shall be no more than two kinds, the first one is 48mm in the outside diameter and the other one is 51mm in the diameter. And all their wall thickness shall be 3mm as the biggest.