Steel scaffolding system, as one of the infrastructure equipment on the construction site, has enjoyed a wide application on various projects, compositing an indispensible part of erecting scaffolds. In order to assure its role in the scaffolding system of connecting and fixing, the quality of scaffolding clamp its own and the fastening degree it have shall be discreetly inspected as they will greatly influence bearing capacity, stability and the safety ratio of the whole scaffolding structure.

However, according to a research conducted in the coupler market, the average quality level of couplers is not so satisfying and optimistic.In order to enhance the quality insurance of construction couplers, the relative national departments have implemented administrative regulations and laws on construction products. Manufacturers are required to provide aptitude qualifications before and after manufacturing coupler products.

Due to the working load on the scaffold is delivered to every tube by couplers, the couplers are required to have some certain mechanical properties such as anti-contortion, anti-damage and anti-slip, among which the anti-slip is an inspecting standard over position changing of clamps, and anti-contortion over contortion ratio of single side of the clamp and anti-damage over the load bearing property.