High Strength Bolts 8.8 10.9 12.9 - China Suppliers & Factory for Black Large Hexagon Bolts
Production parameter
| thread specification d |
(M39) | M42 | (M45) | M48 | (M52) | M56 | M64 | |
| P | pitch | 4 | 4.5 | 4.5 | 5 | 5 | 5.5 | 6 |
| b | reference | 68 | 74 | 76 | 82 | 85 | 90 | 100 |
| c | Min | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 |
| Max | 1 | 1 | 1 | 1 | 1 | 1 | 1 | |
| da | Max | 45 | 48 | 52 | 55 | 60 | 64.2 | 73.2 |
| ds | nominal | 39 | 42 | 45 | 48 | 52 | 56 | 64 |
| Min | 38 | 41 | 44 | 47 | 51 | 54.8 | 62.8 | |
| Max | 40 | 43 | 46 | 49 | 53 | 57.2 | 65.2 | |
| dw | Min | 60 | 64.7 | 69.45 | 74.2 | 78.8 | 83.4 | 92.9 |
| e | Min | 71.3 | 76.95 | 82.6 | 88.25 | 93.79 | 99.2 | 110.5 |
| k | nominal | 25 | 26 | 28 | 30 | 33 | 35 | 40 |
| Min | 23.95 | 24.95 | 26.95 | 28.95 | 31.75 | 33.75 | 38.75 | |
| Max | 26.05 | 27.05 | 29.05 | 31.05 | 34.25 | 36.25 | 41.25 | |
| k1 | Min | 16.76 | 17.46 | 18.86 | 20.26 | 22.23 | 23.63 | 27.13 |
| r | Min | 2.5 | 2.5 | 3 | 3 | 3.5 | 3.5 | 4 |
| s | Max=nominal | 65 | 70 | 75 | 80 | 85 | 90 | 100 |
| Min | 63.1 | 68.1 | 73.1 | 78.1 | 83 | 87.8 | 97.8 | |
| Thread b | - | - | - | - | - | - | - | |
Production description
Bolts made of high-strength steel or requiring significant pre tightening force can be referred to as high-strength bolts. High strength bolts are commonly used for connecting bridges, steel rails, high-voltage and ultra-high voltage equipment. The fracture of this type of bolt is mostly brittle fracture. High strength bolts applied to ultra-high pressure equipment require significant prestressing to ensure the sealing of the container.
Some concepts about high strength bolts
According to the provisions of the bolt performance grade in 8.8 or above, known as high-strength bolts. As of March 2020, China's national standard only listed to M68. For large size specifications, especially the length of the bolt itself 10 ~ 15 times of high-strength bolts, finished products are rare, a small number of domestic manufacturers in China can be customized. [1-2][3] high-strength bolt and ordinary bolt difference: high-strength bolt is able to withstand the load than the same specification of ordinary bolt to be greater. The material of ordinary bolts is made of Q235(A3) . High strength bolt material 35 # steel or other high-quality materials, made after heat treatment, improve the strength.
Frequently Asked Questions
What are high-strength bolts?
Bolts made of high-strength steel or those requiring significant pre-tightening force are referred to as high-strength bolts. They are commonly used for heavy-duty connections in bridges, steel rails, and high-voltage equipment.
What defines the performance grade of a high-strength bolt?
According to standard specifications, bolts with a performance grade of 8.8 or above are classified as high-strength bolts.
What is the difference between high-strength bolts and ordinary bolts?
High-strength bolts can withstand significantly greater loads than ordinary bolts of the same specification. Ordinary bolts are typically made of Q235(A3) steel, whereas high-strength bolts are made of 35# steel or other high-quality materials and undergo heat treatment to enhance their strength.
Why do ultra-high pressure equipment require high-strength bolts?
High-strength bolts used in ultra-high pressure equipment require significant prestressing (pre-tightening force) to ensure the complete and secure sealing of the pressure container.
Are large-size high-strength bolts readily available?
Large-sized high-strength bolts, especially those with lengths 10 to 15 times their diameter, are rare as standard finished products. However, they can be custom-manufactured by a small number of specialized domestic manufacturers.