The number of specifications of high-strength bolts should be calculated according to the diameter requirements of the design, according to the length of the actual construction, according to the actual needs of the construction, the distribution of construction points, the processing quality of the components and the damage of the transportation, the storage and transportation conditions of the site, the difficulty of the project. And other factors, consider the loss of 2-5%, and make purchases.

High-strength bolts used in construction must comply with the "large hexagon bolts for steel structures" (GB1228), "high-strength washers and dimensions for steel structures" (GB1229), "large hexagon bolts for steel structures, large hex nuts, gasket technology" (GB1231), "Twist-cut type high-strength bolt connection form size for steel structure" (GB3632), "Technical conditions for torsion-shear type high-strength bolt connection for steel structure" (GB3633) and other relevant standards.

High-strength bolted joints must be factory-finished after the following tests meet the requirements of the specification:
1) Proof or test of the material number, production lot number, chemical properties and mechanical properties of the material.
2) Wedge load test of bolts.
3) Guaranteed load test of the nut.
4) Hardness test of nuts and washers.
5) Torque coefficient test of the connecting piece (specify the test temperature). Torque coefficient mean and standard deviation of large hexagonal joints; mean value and coefficient of variation of tightening axial force of torsion-shear joints.
6) Test the tightening axial force coefficient.
7) Product specifications, quantity, date of manufacture, packing list.

Related Recommendations: High Strength Fasteners Standard Data Query - High Strength Bolts | High Strength Nuts | High Strength Washers | High Strength Connections

GB / T 1228-2006 high strength large hexagon bolt for steel structure

GB / T 1229-2006 high strength large hex nut for steel structure

GB / T 1230-1995 high strength washers for steel structures

GB / T 3632-2008 Torsional shear type high strength bolt connection pair for steel structure

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