The unsafe factors in the use of construction fasteners are:

① construction fastener source messy, uneven quality, especially the low price of low-quality fasteners into the construction site;

② old fastener bolts have slip wire, but still reluctant to use. The construction fasteners are steel stamping and malleable cast iron. It is used for erection of the template support frame for malleable cast iron fasteners, the material is not less than KTH33008 malleable cast iron, its mechanical properties: tensile strength 330N / mm, elongation 8%, hardness HB120 ~ 163. Malleable cast iron is made of a certain component of the white cast iron by graphite annealing, than the gray cast iron has a high toughness, used for manufacturing to withstand the impact of the castings.

The basic requirements for the detection of construction fasteners are as follows:

① new fasteners must have product quality certificate, production license, professional testing units of the test report;

② fastening bolts tightening torque of 70N · m, the forging parts fasteners shall not be destroyed. Construction fasteners to understand these in the use of construction fasteners in the process must pay attention.