Fastener knowledge: three safety points for tower crane bolts

Tower cranes are large-scale machinery, which have high requirements for safety and quality, and bolts are the most important connecting parts on the tower crane. They also play a vital role in the safety of the tower crane, so for the safety performance of the tower crane bolts.

First, when the tower crane is working, when the pre-tightening force of a group of connection pairs at the same connection is too large, the axial force of the bolts of each connection pair will be very different, and the bolts with large pre-tightening force Under heavy load for a long time, fatigue fracture is prone to occur. In the actual inspection, one of the eight foundation bolts was also found to be fractured, which belongs to this phenomenon. Pay attention to the consistency of the pre-tightening torque during the installation, and during the field operation, due to the different strength of the workers, it is very likely that the pre-tightening torque of the four stud bolts is different. The use of a torque wrench can be better controlled. Take a step back, and it should also be experienced The band master also checked and adjusted the tightening. (Guide: Methods of preventing loosening of threaded fasteners)

Second, when the tower crane is in transition, all the tower connecting bolts should be inspected in detail, rust removed, and lubricated. If any abnormalities such as cracks, wear, severe corrosion, overall or local plastic deformation, etc. are found, they must be replaced. It is recommended that it should not be used more than twice to avoid fatigue damage. This requirement may not be met by most existing tower cranes. If a shortage is found, it is not advisable to process and make it by yourself. Because the construction unit is not easy to control the processing quality and material of the high-strength bolts, it is better to buy from the original tower crane manufacturer. The high-strength bolts should be marked by the manufacturer and grade.

Third, after the initial installation of the tower crane, the tightening of all connecting bolts should be checked once after running 2 shifts, and once every half a month or so. After the tower is upgraded, the key inspection of the bolts in the above parts should be carried out. . The position of the tower arm should also be rotated during inspection, and the bolt to be inspected is directly below the position of the balance arm, so that it is credible and effective to check whether the bolts are tightened.

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