Inspection system for tightening of high strength bolts

1。 After the final tightening of high-strength bolts, the on-site technical personnel shall send the final tightening inspection notice to the laboratory in time, and the laboratory must make preparations before the final tightening inspection.
2。 The final tightening inspection on site must be completed within 4H ~ 24h after the completion of high bolt tightening. The final screwing inspection shall be carried out by the test personnel in the work area, and the cooperation work shall be well done on site.
3。 Before inspection, the torque wrench must be calibrated, and the torque error should not be greater than ± 3% of the torque value used.
4。 The initial tightening inspection shall be carried out by on-site technicians. Knock on the opposite side of the nut with a small hammer weighing about 0.3KG, and hold the opposite side of the nut tightly with fingers for inspection. If the vibration is large, it is regarded as unqualified, and the initial tightening shall be conducted again.
5。 Before the final tightening inspection, the on-site technicians should observe all the high-strength bolt connection pairs after the final tightening, and check the relative positions of the bolts and nuts marked with paint rings after the initial tightening, so as to check whether the final tightening is missed.
6。 The final tightening inspection times must be in strict accordance with the specification requirements. At the joint of main truss beam, longitudinal beam and cross beam, 5% of the total number of high-strength bolt connection pairs of each bolt group, but not less than 5 sets, each node shall be inspected with at least 1 set of tightening torque.

7。 Check the torque value of the nut after final tightening, and the deviation shall not exceed 10% of the torque value, otherwise it is unqualified.
8。 The proportion of unqualified bolts in the total number of spot checks of each node shall not exceed 20%. If more than 20%, the spot check shall be continued until the cumulative qualified rate reaches 80%.
9。 If the tightening is insufficient, it should be supplemented in time. If the tightening is excessive, the bolt should be replaced and re tightened.
10。 In the process of inspection, the experimenter must make the original record and file it in time.
11。 After the test, the laboratory should release the relevant data in time.
Main products: steel structure bolts and nuts, high strength bolts and nuts, hexagon bolts, hexagon nuts, chemical bolts and nuts and other special-shaped parts.