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Structural bolts are high-strength fasteners engineered for critical load-bearing connections in steel structures, where joint integrity and safety are non-negotiable. Designed to meet stringent standards such as ASTM A325, ASTM A490, DIN 6914, and ISO 7412, these bolts are widely used in construction, infrastructure, and heavy engineering projects. Their primary function is to create secure, high-preload joints capable of withstanding dynamic loads, vibration, and environmental stress.
Unlike standard fasteners, structural bolts operate under controlled tension, often used in friction grip connections to prevent slippage between steel plates. This makes them essential in applications such as bridges, high-rise buildings, and industrial frameworks. Material options typically include high tensile carbon steel and alloy steel, with surface treatments tailored for corrosion resistance and durability.
KK Fasteners supplies structural bolts to global infrastructure and engineering projects, with consistent dimensional accuracy and full material traceability aligned to international compliance requirements.
| Parameter | Specification |
|---|---|
| Material | Carbon Steel, Alloy Steel |
| Grades | ASTM A325, ASTM A490, DIN 6914, ISO 7412 |
| Size Range | M12 to M36 / 1/2" to 1-1/2" |
| Thread Type | Metric, UNC, UNF |
| Standards | ASTM, DIN, ISO, BS, EN |
| Surface Finish | Black Oxide, Hot Dip Galvanized, Zinc Plated, PTFE Coated |
| Type Variants | Heavy Hex Bolts, Tension Control Bolts, Friction Grip Bolts |
| Tensile Strength | A325: ~830 MPa, A490: ~1040 MPa |
| Hardness | Rockwell C25–C34 (depending on grade) |
| Bolt Diameter | D | F | C | H | T | |||||
|---|---|---|---|---|---|---|---|---|---|---|
| Body Diameter | Width Across Flats | Width Across Corners | Height | Thread Length | ||||||
| Max | Basic | Max | Min | Max | Min | Basic | Max | Min | Basic | |
| 1⁄2 | 0.515 | 7⁄8 | 0.875 | 0.850 | 1.010 | 0.969 | 5⁄16 | 0.323 | 0.302 | 1.00 |
| 5⁄8 | 0.642 | 11⁄16 | 1.062 | 1.031 | 1.227 | 1.175 | 25⁄64 | 0.403 | 0.378 | 1.25 |
| 3⁄4 | 0.768 | 11⁄4 | 1.250 | 1.212 | 1.443 | 1.383 | 15⁄32 | 0.483 | 0.455 | 1.38 |
| 7⁄8 | 0.895 | 17⁄16 | 1.438 | 1.394 | 1.660 | 1.589 | 35⁄64 | 0.563 | 0.531 | 1.50 |
| 1 | 1.022 | 15⁄8 | 1.625 | 1.575 | 1.876 | 1.796 | 39⁄64 | 0.627 | 0.591 | 1.75 |
| 11⁄8 | 1.149 | 113⁄16 | 1.812 | 1.756 | 2.093 | 2.002 | 11⁄16 | 0.718 | 0.658 | 2.00 |
| 11⁄4 | 1.277 | 2 | 2.00 | 1.938 | 2.309 | 2.209 | 25⁄32 | 0.813 | 0.749 | 2.00 |
| 13⁄8 | 1.404 | 23⁄16 | 2.188 | 2.119 | 2.526 | 2.416 | 27⁄32 | 0.878 | 0.810 | 2.25 |
| 11⁄2 | 1.531 | 23⁄8 | 2.375 | 2.300 | 2.742 | 2.622 | 15⁄16 | 0.974 | 0.902 | 2.25 |
|
Dimensions per ASME B18.2.6 2011 |
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Structural bolts are used to create high-strength, load-bearing connections in steel structures where safety, stability, and long-term performance are essential.
Structural bolts are typically produced through hot forging or cold forging processes, followed by precision machining and thread rolling to achieve exact dimensional specifications. Heat treatment processes such as quenching and tempering are applied to attain required mechanical properties.
Quality assurance includes dimensional inspection using calibrated gauges, tensile and hardness testing, and coating thickness verification for corrosion protection. Each batch undergoes traceability checks to ensure compliance with ASTM and ISO standards. KK Fasteners maintains documented inspection protocols aligned with ISO 9001 requirements, ensuring consistent performance across bulk orders.
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Structural bolts are high-strength fasteners specifically designed for load-bearing steel connections. They are manufactured to standards such as ASTM A325 and A490 and are used in critical applications where joints must withstand heavy loads, vibration, and environmental stress without failure.
Structural bolts are primarily made from high tensile carbon steel and alloy steel. Carbon steel grades like A325 provide reliable strength for general applications, while alloy steel grades such as A490 offer higher tensile strength and improved performance under heavy loads and demanding conditions.
Structural bolts are governed by international standards including ASTM A325, ASTM A490, DIN 6914, and ISO 7412. These standards define mechanical properties, dimensions, and performance requirements to ensure safety and consistency in structural applications worldwide.
The correct grade depends on load requirements, environmental exposure, and project specifications. A325 bolts are suitable for standard structural applications, while A490 bolts are recommended for high-stress environments such as bridges and high-rise buildings where greater tensile strength is required.
A reliable supplier should provide ISO-certified production, full material traceability, and compliance with ASTM or DIN standards. It is also important to evaluate export experience, quality documentation, and consistency in supply. Companies like KK Fasteners meet these criteria for global projects.
Structural bolts play a critical role in ensuring the safety and reliability of modern steel structures. With controlled manufacturing processes, strict quality checks, and global supply capability, KK Fasteners supports infrastructure and engineering projects with dependable fastening solutions. For detailed specifications or project-based requirements, request a quote or connect with the technical team to evaluate the right structural bolt configuration.
