- Ningbo Zhongli bolts manufacturing Co., Ltd. +86-574-86587617
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Premium-grade serrated flange bolts engineered to meet the most demanding structural and industrial construction requirements worldwide.
A serrated flange bolt is a specialized high-strength fastener featuring an integrated flanged washer beneath the bolt head, with serrations (teeth) machined directly into the flange face. This unique design eliminates the need for a separate washer while delivering superior clamping force, anti-loosening performance, and load distribution — making it an ideal fastener for demanding construction environments.
🔩 Key Engineering Advantage: The serrated teeth bite into the mating surface under torque, creating a mechanical lock that resists vibration-induced loosening — a critical requirement in structural steel construction, bridge engineering, and heavy industrial assembly.
Conforming to DIN6921 standards and available in Grade 8.8 and Grade 10.9, serrated flange bolts are manufactured from high-strength carbon steel or alloy steel with surface treatments including black oxide, zinc plating, and hot-dip galvanizing. The flange distributes clamping load over a larger surface area, reducing the risk of surface damage or deformation on softer substrates.
In modern construction, where structural reliability and long-term joint integrity are non-negotiable, the serrated flange bolt has become a preferred fastening solution across steel frame buildings, curtain wall systems, modular construction, industrial machinery mounts, and infrastructure projects globally.
Ningbo Zhongli Bolts Manufacturing Co., Ltd. produces DIN6921 Hex Flange Bolts in Grade 8.8 and Grade 10.9 with serration, covering diameters from M10 to M48, with unlimited length options and multiple surface finishes to meet project-specific requirements.
The construction fastener industry is experiencing robust growth driven by global infrastructure investment, urbanization, and the rise of prefabricated modular construction.
From skyscraper steel frames to offshore platforms, serrated flange bolts deliver unmatched anti-vibration clamping performance across the most critical construction environments.
In multi-story steel-framed structures, serrated flange bolts provide secure, vibration-resistant connections for primary and secondary structural members. Their integrated flange eliminates washer misalignment during erection, speeding up assembly while maintaining EN14399 and ASTM A325 structural integrity requirements.
Bridge girder connections, expansion joints, and bearing plate assemblies demand fasteners that maintain clamping force under constant dynamic loading. Serrated flange bolts in Grade 10.9 with hot-dip galvanizing are widely specified for suspension bridges, highway overpasses, and railway viaducts where corrosion resistance and fatigue life are paramount.
Petrochemical plants, power generation facilities, and heavy manufacturing installations rely on serrated flange bolts for equipment base plate anchoring, pipe flange connections, and structural support frames. The anti-loosening serration is critical where machinery vibration would otherwise cause conventional bolts to back off over time.
Renewable energy construction is among the fastest-growing application sectors. Serrated flange bolts secure photovoltaic mounting systems, wind turbine tower flanges, and substation structural steelwork. Their self-locking capability reduces maintenance intervals and long-term operational costs in remote installation sites.
Metro systems, light rail networks, and high-speed rail construction use serrated flange bolts extensively for track support structures, station canopy steelwork, and tunnel lining anchors. Vibration-induced loosening is eliminated by the serrated bite pattern, ensuring passenger safety and reducing track maintenance costs.
The global shift toward off-site prefabrication and modular building systems has dramatically increased demand for reliable, quick-install fasteners. Serrated flange bolts enable fast, accurate module-to-module connections without additional washers, reducing on-site assembly time by up to 30% compared to conventional bolt-washer-nut assemblies.
Several macro-level construction and manufacturing trends are reshaping the demand landscape for high-performance serrated flange fasteners through 2030 and beyond.
LEED-certified and net-zero construction projects increasingly specify hot-dip galvanized serrated flange bolts for their 50+ year corrosion protection lifecycle. Reduced maintenance requirements align with whole-building lifecycle cost analysis, driving specification of premium fasteners over standard alternatives.
Advanced manufacturers like Zhongli Bolts are integrating automated cold-forging lines, real-time process monitoring, and AI-assisted quality inspection systems. This elevates dimensional consistency and mechanical property repeatability to levels previously unachievable, meeting the tightest construction specification tolerances.
Government-backed infrastructure programs across the US (IIJA), EU (Cohesion Fund), Southeast Asia (ASEAN connectivity), and the Middle East (Vision 2030) are generating unprecedented demand for structural fasteners. Serrated flange bolts are specified in steel-intensive mega-projects including airports, ports, data centers, and smart city developments.
EN14399, EN15048, ISO898-1, and ASTM standards are being more rigorously enforced in procurement specifications globally. Manufacturers holding CE marking, ISO9001, and AD2000 certifications — like Zhongli Bolts — gain competitive advantage as project owners demand full documentation and traceability from fastener suppliers.
Post-earthquake reconstruction and new seismic zone construction codes increasingly require friction-type high-strength bolt assemblies. Serrated flange bolts with Grade 10.9 or Grade 12.9 ratings provide the preload stability and slip resistance needed for moment-resisting frame connections in earthquake-prone regions across Asia, the Americas, and Southern Europe.
Beyond traditional zinc plating, construction-grade serrated flange bolts are increasingly available with geomet coating, dacromet treatment, and mechanical zinc deposition — offering enhanced corrosion protection for coastal, marine, and chemically aggressive environments without the hydrogen embrittlement risk associated with electroplating on high-strength grades.
Founded in 2003, Ningbo Zhongli Bolts Manufacturing Co., Ltd. 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, and its products are exported to Europe, USA, Middle East, Africa, Southeast Asia and other regions. With strong technical capabilities, complete testing equipment, and a variety of fully automatic multi-station cold and hot heading machines, Zhongli Bolts consistently delivers reliable, high-quality fastener products.
Through rigorous scientific management, Ningbo Zhongli Bolts Manufacturing Co., Ltd. has obtained the ISO9001 Quality Management System certificate. The company has also achieved EN15048 CE, EN14399 CE, AD2000, and CE certifications, underscoring its commitment to international quality standards.
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Our main products under the ZYL brand encompass a comprehensive range of structural fasteners engineered for construction applications. Our hex bolts portfolio includes ASTM A325 Type 1, A490, hex head bolts DIN931, DIN933, EN14399, DIN6914, ISO4014, ISO4017 in Gr8.8, Gr10.9, and Gr12.9, as well as ANSI B18.2.1 UNC and UNF Gr5 and Gr8 for North American construction markets.
Fine pitch hex bolts DIN960 and DIN961 in Gr8.8, Gr10.9, and Gr12.9 are available with surface finishes including Black oxide, Zinc plated, and Hot-dip galvanized. Hex socket cap screws DIN912 and ISO4762 cover Gr8.8 through Gr12.9 with the same surface treatment options. Diameters range from M10 to M48 with unlimited length availability.
Hex Flange Bolts DIN6921 Gr8.8 and Gr10.9 with serration represent our flagship construction fastener product — delivering superior anti-loosening performance for structural steel, modular building, and industrial installation applications. Thread rod A193 B7 in long and short sizes with 2H nuts, and stud bolts complete our structural fastener offering.
We also supply hex nuts DIN934 and DIN6915, plain washers DIN125, DIN126, and DIN6916, and spring washers DIN127 — all available in Black, Zinc plated, and Hot-dip galvanized finishes. Physical and mechanical test results conform to ISO898-1 for bolts and ISO898-2 for nuts.
Every serrated flange bolt undergoes a rigorous 8-stage manufacturing process, from certified raw material sourcing to final container loading — ensuring consistent quality for construction-critical applications.
Our 10,000 m² manufacturing facility is equipped with fully automatic multi-station cold and hot heading machines, precision thread rolling equipment, and advanced heat treatment furnaces.
Five core pillars that make Zhongli Bolts the preferred serrated flange bolt supplier for construction projects worldwide.
A Professional Sales and Technical Team with More Than 20 Years of Industry History.
Own Testing Equipment and Laboratory. Products undergo Initial Inspection, Patrol Inspection, and Final Inspection.
Our Factory Has Its Own Cold Forged, Hot Forged, and Heat Treatment Equipment for complete in-house production control.
Standard Fasteners in Stock. Non-standard and custom-specification Fasteners Can Be Manufactured to order.
We Have Passed ISO 9001, EN 15048, EN 14399, AD2000 and CE Certificates — fully documented quality assurance.
Every serrated flange bolt produced at Zhongli Bolts undergoes a comprehensive three-stage inspection protocol to ensure full compliance with DIN6921, ISO898-1, and customer-specific construction project requirements.
We hope to establish business relationships with partners all over the world, and our business can bring mutual benefits for both parties.
EN 15048 CE Certification · EN14399 CE Certification · ISO9001 Certificate · AD2000 · CE Marking — Full compliance documentation available for construction project specification requirements.
Grasp first-hand information — real feedback from construction procurement managers and project engineers worldwide who rely on Zhongli Bolts for their structural fastener requirements.
Contact Zhongli Bolts today for competitive pricing, free samples, and technical consultation. We serve construction procurement teams across Europe, North America, the Middle East, Southeast Asia, and Africa.
Browse our complete portfolio of high-strength bolts, stud bolts, hex socket screws, and structural fasteners — all manufactured to international standards for construction applications.
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