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How to divide the strength grade of bolts
How bolts are divided into strength grades: The performance grades of steel structure connecting bolts are divided into more than 10 grades, such as 3.6, 4.0, 4.8, 5.6, 6.8, 8.8, 9.8, 10.9, 12.9. The specific meaning of bolt grades is, for example, bolts of grade 4.8 representing tensile strength. 0.8 represents the ratio of strength divided by tensile strength, that is, the tensile strength of grade 4.8 bolts is 400MPa, and the strength is 400 × 0.8 = 320MPa. Other bolt grades have the same meaning.
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What is the standard and acceptance for installing steel structure bolts?
Steel structure bolts play a linking role in machinery. Bolts are needed in many places to fix, so what are the standards and acceptance for installing steel structure bolts? Please take a look with the editor of Xinmo Fasteners. What is the standard and acceptance for installing steel structure bolts? 1. Hit the high-strength bolts with a 0.3kg hand hammer for census to check whether there is any leakage; the tightening of the high-strength bolts with large hexagon heads should be divided into initial and final screwing; the tightening of torsion shear type high-strength bolts should be divided into initial screwing and final screwing. For large nodes, it should be divided into initial screwing, re-screwing, and final screwing, and the re-screwing torque is equal to the initial screwing torque.
What are high-strength bolts, the characteristics of high-strength bolts and their transportation requirements
High-strength bolts (referred to as high-strength bolts) refer to bolts made of high-strength steel or that need to be prestressed. They are one of the main connection methods of bridge steel structures. High-strength bolts are mostly used for the connection of bridges, rails, high-pressure and ultra-high-pressure equipment. High-strength bolts used in ultra-high-pressure equipment need to be prestressed to ensure the sealing of containers. In recent years, due to the influence of many factors such as the use environment, some bridges have experienced high bolt delay fracture and fall off. The fracture of such bolts is mostly brittle fracture, which may lead to slippage of the connecting nodes, instability and damage of the main structure of the steel bridge, and risk of hitting vehicles and pedestrians. Different from ordinary bolts, high-strength bolts are fasteners with strong fastening ability, and the requirements for storage, transportation and storage are relatively high. According to its fastening principle, it is required that every link of high-strength bolt connections from factory to installation must be maintained in the factory state, that is, the torque coefficient and standard deviation of the same batch of large hexagon head high-strength bolt connections remain unchanged. Keep the axial force and standard deviation of the torsional shear type high-strength bolt connection pair unchanged. It should be said that for the large hexagonal head bolt connection pair, if the state changes, it can be remedied by adjusting the construction torque, but the torsional shear type high-strength bolt connection pair has no chance of remediation, and can only be solved by the torque method or the angle method.
How to effectively avoid rusting of hot-dip galvanized bolts
Hot-dip galvanized bolts are a relatively good anti-rust surface, but in the face of weathering and corrosion in nature, rust appears. In order to avoid this phenomenon, the following measures will be taken.