To put it bluntly, the nut of the large hexagon bolt is a regular hexagon. It can be inferred that this is also designed for the convenience of fixing with a wrench, and this is also the type of bolt used at the beginning. When to use large hex bolts? When to use torsional shear bolts? Under the premise of the same compressive strength and different structure of the wrench, the construction space of the torsional shear type is small, and the bolt head should be twisted and broken by the torsional shear type. There are two sealing rings for the connection of large hexagonal bolts, one on the top of the head and one on both sides of the nut, and one sealing ring on the side of the nut for torsional shear bolts. Large hexagon head bolts are divided into grades 8.8 and 10.9, while torsional shear bolts are only divided into grade 10.9. Use a torque wrench for large hexagon head bolts; use an electric wrench to twist the torx head for bolts with torsional shear type. The final torsion torque of the large hexagon cannot be well controlled during construction, and it is not suitable for torsion and inspection at high altitudes, while the good operation of the torsion cutting type can be checked by looking at it. The large hexagon head bolt adopts the torque controller structure, and the torque controller needs to be divided into two parts: the original and the final twist. The construction is cumbersome and the quality control is not very good. Personal opinion: Grade 10.9 torsional shear bolts are stronger. In addition to the above suggestions, there are also torsional shear bolts whose spacing exceeds that of high-toughness large hexagonal head bolts. For example, the i]-shaped steel frame is matched with the blue plate torsional shear type with large and thick hexagonal head types, resulting in a 1-5% increase in steel consumption, and the price of the large hexagonal head is lower than that of the torsional shear type. - General steel frame manufacturers use large hexagonal heads as gantry frames, and multi-story buildings use torsional shear type. There are also large hexagonal head types that also have electric wrenches. For example, the distance between the large hexagonal head bolts and the structure of the electric wrench should be relatively improved. The large hex bolt consists of a fixed torque wrench. Since they are not encapsulated in the screw when they are twisted, they can push the extruder screw "back and forth" when the nut is turned, which wastes torque unnecessarily and makes it impossible to tighten them. Therefore, the screw head is designed as a solid hexagon. Under the premise of co-rotating, the screw head can be temporarily fixed with a general wrench to prevent co-rotating.