High Strength Bolts 8.8, 10.9, 12.9 - China Suppliers & Factory for Black Large Hexagonal 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. 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
Q What performance grade defines a high-strength bolt?
According to standard provisions, bolts with a performance grade of 8.8 or above are classified as high-strength bolts.
Q What are the typical applications of high-strength bolts?
They are commonly used in heavy-duty connections such as bridges, steel rails, high-voltage equipment, and ultra-high voltage installations.
Q How do high-strength bolts differ from ordinary bolts in load capacity and materials?
High-strength bolts can withstand significantly higher loads than ordinary bolts of the same size. Ordinary bolts are made of Q235(A3) steel, whereas high-strength bolts are manufactured from 35# steel or other premium materials followed by heat treatment to boost strength.
Q Why is prestressing critical for high-strength bolts in ultra-high pressure systems?
High-strength bolts used in ultra-high pressure equipment require a substantial pre-tightening force (prestressing) to guarantee the reliable sealing of the pressure container.
Q Are extra-large or ultra-long high-strength bolts standard products?
No, national standards in China list specifications up to M68. Extremely large bolts, especially those with lengths 10 to 15 times their diameter, are rare and typically require custom manufacturing.
Q What type of fracture do high-strength bolts usually experience?
The structural failure or fracture of high-strength bolts is mostly characterized as brittle fracture.