Notes for using Fasteners
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Update time : 2020-12-23 20:23:06
Fasteners are a type of mechanical parts that are used for fastening and connection and are extremely widely used. They are also necessities that we rarely pay attention to in our lives. A little negligence will cause more or less damage, ranging from small property to large personal Safety. Therefore, when using fasteners, you must have a certain understanding of its regulations.
According to rough statistics, there are more than 40,000 varieties and millions of fasteners in various types and specifications, and their use occasions and environments are ever-changing. Fasteners, as the connecting parts of the mainframe and components, together with the mainframe undertake the basic performance of the main body and the basic functions of the components. It must adapt to high temperature, high pressure, low temperature, vibration, corrosion, heavy load, alternating stress, and shear resistance. Cut torsion and other occasions. However, the probability of accidents caused by fastener failure is very high, so the materials used to manufacture the fasteners must be strictly selected in advance.
1. General bolts, high-strength large hexagon head bolts, high-strength bolts and other fasteners for steel structure connection.
2. For high-strength large hexagon head bolts and high-strength bolts, there should be factory qualified inspection reports for torque coefficient and tightening axial force (pre-tension) respectively. When high-strength bolts are used after being stored for more than 6 months, the torque coefficient or tightening axial force test shall be carried out again according to relevant requirements, and they shall be used after being qualified.
3. For high-strength large hexagon head bolts and high-strength bolts, the torque coefficient and tightening axial force (pre-tension) should be retested respectively. The test bolts should be randomly selected from the bolt batches to be installed at the construction site, and each batch should be selected 8 sets Connect the deputy for reinspection.
4. The safety level of the building structure is Class I. For bolted spherical joint steel grid structures with a span of 40m and above, the surface hardness test of the high-strength bolts should be carried out. The surface hardness of the high-strength bolts of 8.8 should be HRC21~29. The surface hardness of 10.9 grade high-strength bolts should be HRC32~36, and there should be no cracks or damage.
5. When ordinary bolts are used as permanent connecting bolts, and the design documents require or have doubts about their quality, the bolts shall be re-inspected with the minimum tensile load in kind. During the re-inspection, bolts of each specification shall be spot-checked.
