Big Diameter Hex Bolts for Metal Structure Works

In heavy metal structure applications, fastener choice determines both assembly speed and long-term stability. Our Heavy Duty Hex Head Bolts for Structural Steel are purpose-built for bridges, tower cranes, and industrial frames where shock and vibration are constant. They combine precise thread rolling with controlled heat treatment to maintain ductility under extreme loads. For steel frame erection and moment-resisting connections, we supply Large Size Structural Hex Bolts for Steel Frame, manufactured to strict head-to-shank concentricity tolerances that eliminate stress risers. When engineering demands push beyond standard diameters, our Extra Large Hex Fasteners for Steel Building deliver unmatched shear resistance and fatigue performance, tested extensively for skyscraper columns, stadium trusses, and heavy-equipment anchorage systems.

Big Diameter Hex Bolts for Metal Structure Works are produced from carbon steel, alloy steel, and stainless steel grades with full traceability from melt to finished part. The head geometry follows ISO 4014, DIN 931, and ASME B18.2.1 standards, ensuring compatibility with standard heavy hex sockets and hydraulic wrenches. Each production batch undergoes mechanical testing for proof load, ultimate tensile strength, and hardness, with optional Charpy impact testing for low-temperature service. Hot-dip galvanized, zinc flake, and Xylan finishes extend corrosion protection to meet C3, C4, and C5 environmental classifications. thread inspection is carried out with go/no-go ring gauges and optical comparators, and magnetic particle inspection is available for critical applications.

Core Product Specifications

• Diameter range: M12 to M64 (1/2″ to 2-1/2″) in metric and imperial series
• Lengths: 35 mm to 600 mm (1-1/4″ to 24″), longer upon request
• Material grades: 4.6, 8.8, 10.9, 12.9, A325 Type 1/2/3, A490, A354 BD, A193 B7, stainless A2-70, A4-80
• Thread tolerance: 6g for metric, Class 2A for unified threads
• Head style: Hexagon heavy series, with flange option available
• Surface options: black oxide, zinc electroplated (CR3+), hot-dip galvanized (min 50µm), Dacromet, Geomet, Xylan
• Certifications: EN 10204 3.1 / 3.2, factory test reports included
• Marking: grade symbol and manufacturer ID on every bolt head
• Packaging: plastic crates, steel pallets, sea-worthy bundles with corrosion inhibitors

Typical Mechanical Properties Table

Installation is streamlined by the heavy hex head, which provides ample wrench clearance for hydraulic torque tools and impact guns. Recommended torque values follow EN 14399-2 for preloaded assemblies or RCSC guidelines for structural joints. Direct tension indicators and load-indicating washers can be supplied alongside to verify clamp force on site.
Big Diameter Hex Bolts for Metal Structure Works find regular use in pre-engineered steel buildings, pedestrian and highway bridge connections, wind turbine foundations, crane rails, and offshore topside modules. Custom full-thread variants, captive washer assemblies, and special head markings are available with short lead times. Inventory is maintained in multiple warehouse regions to support project schedules, and all shipments include full mill certification, surface coating reports, and lot identification for transparent quality assurance.