- Ningbo Zhongli bolts manufacturing Co., Ltd. +86-574-86587617
- tan@nbzyl.com
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Structural Hex Socket Head Cap Screws — DIN 912 / ISO4762 for Steel Frame Construction
DIN6914 Structural Hexagon Bolts — High-Strength Gr8.8 for Preloaded Construction Connections
High Tensile Hex Flange Bolt DIN6921 Gr10.9 Black — Heavy-Duty Structural Applications
Carbon Steel Hexagon Head Bolt — Fine & Coarse Thread UNC/UNF for Construction Structures
Structural bolts are heavy-duty fasteners specifically engineered to bear high shear and tensile loads in steel-to-steel connections within buildings, bridges, industrial facilities, and civil infrastructure. Unlike ordinary machine bolts, structural bolts comply with rigorous international standards — including ASTM A325, ASTM A490, DIN6914, EN14399 — ensuring consistent mechanical properties, dimensional accuracy, and surface treatment quality that construction engineers can rely on.
Key Insight: In modern steel-frame construction, the quality of structural bolts directly determines the load-bearing capacity, seismic resistance, and long-term durability of the entire structure. Specifying the correct bolt grade, coating, and standard is a critical engineering decision.
The global construction fastener market has experienced robust growth over the past decade, driven by rapid urbanization, large-scale infrastructure programs across Asia, the Middle East, and Africa, and the accelerating adoption of prefabricated steel structures. According to industry analyses, the structural fastener segment is projected to grow at a CAGR exceeding 5% through 2030, with demand concentrated in high-strength grades (Gr8.8, Gr10.9, Gr12.9 and ASTM A325/A490) and corrosion-resistant surface treatments.
From high-rise curtain wall steel frames and long-span bridge trusses to offshore platform jackets and modular industrial buildings, structural bolts are the invisible backbone of the built environment. Selecting a reliable, certified manufacturer is not merely a procurement decision — it is a fundamental quality and safety commitment.
In multi-story and supertall steel-frame structures, structural bolts — particularly ASTM A325 and A490 heavy hex bolts — connect beam-to-column moment frames and bracing systems. Slip-critical connections using high-strength preloaded bolts per EN14399 / DIN6914 are standard practice to resist wind and seismic lateral forces.
Long-span steel truss bridges and highway overpasses rely on high-strength hex bolts with hot-dip galvanized or weathering-resistant coatings to withstand cyclic traffic loads, vibration, and decades of outdoor exposure. Bolt grades Gr10.9 and ASTM A490 are commonly specified for bridge critical joints.
Process plants, refineries, and power stations require stud bolts (A193 B7 with 2H nuts), heavy hex bolts, and flanged connections capable of maintaining integrity under high temperature, pressure, and corrosive media. Dimensional precision and material traceability are non-negotiable in these environments.
Wind turbine towers use large-diameter structural bolts (M36–M64) in flange ring connections, demanding extreme fatigue resistance and precision preloading. The renewable energy boom has created surging demand for certified high-strength bolts with traceable mechanical test reports.
Railway bridges, metro viaducts, and station steel roofs specify structural bolts meeting EN 14399 for preloaded assemblies. Vibration-resistant thread forms and controlled tightening methods (torque or tension control) are critical to maintaining joint integrity over decades of service.
The rise of off-site prefabricated steel modules and modular buildings has driven demand for standardized, high-consistency structural bolts that allow rapid, precise assembly on-site. Hex socket cap screws and flange bolts are widely used in modular connection systems where access space is limited.
As construction projects push structural steel to its limits, demand for Gr12.9 and ASTM A490 bolts is accelerating. Engineers are specifying higher-grade fasteners to reduce bolt count, lower weight, and simplify connection detailing in complex structures.
Environmental regulations are driving a shift from traditional zinc electroplating toward hot-dip galvanizing, Geomet, and Dacromet coatings that offer superior corrosion protection with lower environmental impact — critical for coastal and marine construction projects.
Leading fastener manufacturers are integrating AI-powered vision inspection systems and automated multi-station cold forging lines to achieve tighter dimensional tolerances and 100% defect detection — raising the quality bar across the industry.
Global construction projects increasingly mandate EN 15048, EN 14399, CE marking, and ISO 9001 certification for structural fasteners. Full material traceability — from steel coil to finished bolt — is becoming a procurement prerequisite in Europe, the US, and the Middle East.
Massive infrastructure investment programs across Southeast Asia, Africa, and the Middle East are fueling unprecedented demand for structural bolts. Projects range from highway bridges and port facilities to data centers and large-scale logistics parks.
Complex architectural structures and specialized industrial equipment increasingly require custom bolt dimensions, non-standard thread pitches, and bespoke surface treatments. Manufacturers with in-house cold/hot forging and heat treatment capability are best positioned to serve these needs.
Ningbo Zhongli Bolts Manufacturing Co., Ltd., founded in 2003, is a professional manufacturer of high-strength fasteners in different specifications for various models. The company covers an area of about 10,000 square meters with a registered capital of 1,500,000 RMB and a total annual productivity of 8,000 tons per year.
The company has established several sales branches across different provinces in China, while its products are exported to Europe, USA, the Middle East, Africa, Southeast Asia, and other regions globally. With strong technical capability, complete testing equipment, and a variety of fully automatic multi-station cold and hot heading machines, Zhongli Bolts delivers reliable, high-quality structural fasteners to demanding construction and industrial projects worldwide.
Our main products under the ZYL brand include a comprehensive range of structural fasteners engineered for construction and industrial applications:
Structural hex bolts ASTM A325 Type 1, A490; hex head bolts DIN931, DIN933, EN14399, DIN6914, ISO4014, ISO4017 Gr8.8, Gr10.9, Gr12.9; ANSI B18.2.1 UNC and UNF Gr5, Gr8; fine pitch hex bolts DIN960, DIN961 Gr8.8, Gr10.9, Gr12.9; hex socket cap screws DIN912, ISO4762 Gr8.8, Gr10.9, Gr12.9 with surface finishes including Black, Zinc Plated, and Hot Dip Galvanized. Diameters range from M10 to M48 with unlimited length options.
Hex flange bolts DIN6921 Gr8.8, Gr10.9 with serration; threaded rod A193 B7 in long and short sizes with 2H nuts; stud bolts for high-pressure and high-temperature flange connections. We also supply hex nuts DIN934, DIN6915; plain washers DIN125, DIN126, DIN6916; and spring washers DIN127 — all available in Black, Zinc Plated, and Hot Dip Galvanized finishes.
Our physical and mechanical test results comply with ISO 898-1 for bolts and ISO 898-2 for nuts. Through scientific management, Ningbo Zhongli Bolts Manufacturing Co., Ltd. has obtained the ISO 9001 Quality Management System Certificate and holds EN 15048, EN 14399, AD2000, and CE certifications.
We hope to establish lasting business relationships with partners all over the world, delivering mutual benefits through quality products, competitive pricing, and responsive service.
A Professional Sales and Technical Team with More Than 20 Years of Industry History.
Own Testing Equipment and Laboratory. Products undergo Initial, Patrol, and Final Inspection.
In-House Cold Forged, Hot Forged, and Heat Treatment Equipment for full process control.
Standard Fasteners in Stock. Non-standard Structural Bolts Can Be Customized to Specification.
Certified to ISO 9001, EN 15048, EN 14399, AD2000, and CE — meeting global construction standards.
Every structural bolt leaving our factory undergoes a comprehensive multi-stage inspection process to ensure compliance with international construction standards and customer specifications.
Hot DIP Galvanizing Structural Hex Bolt — UNC/UNF Thread for Outdoor Construction
Heavy Hexagon-Head Structural Bolts ASTM A325 with Nut — Steel Frame Construction
Hot DIP Galvanizing Hex Bolt — Manufacturer Direct, UNC/UNF for Structural Connections
ASTM A307 / DIN6914 Structural Hexagon Bolts — General Construction Fastening
Hexagon Socket Head Cap Screws DIN912/ISO4762 — Precision Structural Fastening
DIN6914 Structural Hexagon Bolts Gr8.8 — Preloaded Construction Joint Applications
High Tensile Hex Flange Bolt DIN6921 Gr10.9 Black — Heavy Structural Steel
Carbon Steel Hexagon Head Bolt — Fine/Coarse Thread UNC/UNF for Structural Use
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