High Strength Bolts 8.8 10.9 12.9 | China Suppliers & Factory Black Hexagonal Large 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 (FAQ)
Q: What is defined as a high-strength bolt?
Bolts made of high-strength steel or those requiring significant pre-tightening force with a performance grade of 8.8 or above are classified as high-strength bolts.
Q: What are the primary applications of high-strength bolts?
High-strength bolts are commonly used for structural connections in bridges, steel rails, high-voltage, ultra-high voltage equipment, and ultra-high pressure systems that require secure sealing.
Q: How do high-strength bolts differ from ordinary bolts?
High-strength bolts can withstand much larger loads than ordinary bolts of the same size. Ordinary bolts are typically made of Q235(A3) steel, whereas high-strength bolts are made from 35# steel or other premium materials and undergo heat treatment to enhance strength.
Q: What is the largest standard size for high-strength bolts?
According to China's national standards, the listed specifications go up to M68. Larger dimensions or custom lengths (such as 10 to 15 times the bolt's own diameter) require custom manufacturing.
Q: Why is prestressing important for high-strength bolts in high-pressure equipment?
Significant prestressing is crucial to ensure a tight, leak-proof seal for pressure containers and to prevent brittle fracture failures under high operating pressures.