Tighten the torque wrench with the large hexagon high-strength bolt

High strength bolt is high strength bolt, large hexagonal high strength bolt is a kind of high strength bolt, belongs to a kind of standard parts, mainly used in steel structure engineering to join the point. The large hexagon high strength bolt is composed of a bolt, a nut and two washers. The structure of the high strength bolt must be first screwed and then finally screwed. The final tightening of the large hexagon high strength bolt must use a torque wrench. 

electric torque wrench features:

1. with digital display controller, repetition accuracy up to ±3%

2. with mechanical steering, abandon the motor positive and negative rotation, using more advanced mechanical positive and negative rotation, can be limited to improve the service life of the motor

3.the machine is small in size, light in weight and easy to use

Fastening of large hexagon high strength bolts:

1. For permanent torque wrenches fastened by high-strength bolts, check should be carried out before and after the shift, and the torque wrenches with errors greater than 5% should be replaced or re-calibrated

2. high strength bolt fastening should be divided into the initial screw and the final screw two times, the initial screw still can not make the plate stack close to the large node should also be re-screw, until the plate close to the final screw

3. high strength bolts should be applied in the nut province torque, the fastening sequence is generally from the center of the joint order to the outside (three directions), the initial screw, screw and screw after the bolt application of different colors of paint on the nut to make a mark.

Inspection and acceptance of high strength bolts:

1. The torque wrench must be checked before and after the shift, and the error shall not be greater than 3%

2. the number of inspection: 10% of the number of bolts per node, but not less than 1 should be torque sampling test

3. If the error is greater than 3%, the node shall be enlarged by 10% for sampling inspection. If there are still non-conforming nodes, the whole node shall be tightened and checked.

4. The bolts with lower torque limit should be repaired, and the bolts with higher torque limit should be replaced

5. the torque check should be carried out after the final twist for 1h, and the check should be completed within 2h

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