What items are inspected for high-strength bolts to distinguish the quality?

2023/07/25

What items are inspected for high-strength bolts to determine whether the bolts are up to standard? Let's learn more about it. (1) Main inspection items include: minimum load inspection of bolt sundries; re-inspection of pre-tension tension of torsional-shear type high-strength bolt connection pairs; inspection of high-strength bolt connection torque; re-inspection of torque index of high-toughness large hexagon head bolt connection pairs; (2) Main control items ①Steel structure processing and equipment should carry out the anti-skid index test and re-inspection of the contradictory surface of the high-strength bolt connection respectively according to the relevant standards of GB50205-2001 Appendix B. The anti-skid index test of the contradictory surface of the prefabricated component that is solved on the spot should be carried out alone, and the conclusion should conform to the overall planning regulations. ② After the final screwing of the connecting pair of high toughness large hexagonal head bolts, check the final screwing torque within 1 hour and 48 hours, and the results of the checks should meet the standard regulations. Check the total number: check 10% according to the number of nodes, and should not be less than 10 nodes; check 10% of each checked node according to the number of bolts, and should not be less than 2. ③After the final screwing of the torsional shear type high-strength bolt connection pair, except for those whose torx heads cannot be unscrewed with a special wrench due to structural reasons, the number of bolts that do not unscrew the torx heads during the final screwing should not exceed 5% of the number of bolts at this node. For all torsional shear high-strength bolt connections that have not been unscrewed from the torx head, the final torque method or corner method should be used to complete the final tightening and mark it, and the final tightening torque should be checked according to the conditions in item ② above. Total number of checks: Check 10% by the number of nodes, but it should not be less than 10 nodes, and check the final torque of all torsional shear type high-strength bolt connections from the checked point to the torx head that has not been twisted off. (3) General items ①The sequence of tightening of high-strength bolt joints and the torque of initial tightening and re-tightening should conform to the overall planning regulations and the current national standard of our country "Procedures for Planning, Construction and Acceptance of High-strength Bolt Connections in Steel Structures" JGJ82. ②After the high-strength bolts are connected to the pair, the bolt openings should show 2 to 3 threads, and 10% of the bolt threads should show 1 or 4 threads during this period. Check the total number: Check 5% by the number of nodes, and it should not be less than 10. ③The connecting surfaces of high-strength bolts should be kept dry and neat, and there should be no burrs, burrs, welding spatter, welding slag, zinc dust, stains, etc., and the contradictory surfaces should not be painted unless specified by the design. ④ High-strength bolts should be freely inserted into the bolt holes. Oxygen-cut drilling should not be used for high-strength bolt holes. The total number of drill holes should be enlisted in the overall plan and allowed. The diameter after drilling should not exceed 1.2d (d is the bolt hole diameter). ⑤ After the assembly of the bolt ball joint spherical grid frame is completed, the high-strength bolts and the ball joints should be tightened and connected. The thread length of the high-strength bolts screwed into the bolt ball should not be less than 1.0d (d is the diameter of the bolt hole), and there should be no gaps, looseness and other untightened conditions at the connection.

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