What products does Youlong manufacture?

Youlong manufactures photovoltaic mounting components such as aluminum guide rails, water channels, angle brackets and connectors, plus precision fasteners including anchor bolts, carriage bolts, expansion bolts, flat washers and wing nuts for solar, wind power and construction projects.

Can you produce custom PV brackets and fasteners to my drawings?

Yes. Our automated stamping, forging and CNC machining lines support OEM and custom production. Send drawings or samples with material, finish and quantity requirements, and our engineers will confirm feasibility, tolerances and a written proposal.

How do you control the quality of fasteners for outdoor solar projects?

We run random inspections from raw material intake to final dispatch and test against industry standards, including salt spray corrosion testing and tensile strength testing, so that hardware performs reliably in long-term outdoor exposure.

Which material should I choose for coastal or high-humidity PV sites?

For coastal, offshore or industrial sites with high corrosion categories, stainless steel grade 316 (A4) fasteners are generally recommended. For inland sites, 304 (A2) stainless or hot-dip galvanized carbon steel is commonly specified. Isolating washers help prevent galvanic corrosion between aluminum rails and steel hardware.

Where is Youlong located and do you export worldwide?

Youlong is located in Yongnian District, Handan City, Hebei Province, known as China's Fastener Capital. We have served more than 100 clients worldwide with cumulative shipments exceeding 300,000 tonnes.

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Industry White Paper

Global Commercial & Industrial Landscape of Non Serrated Flange Nuts

In advanced structural mechanical design, the selection between serrated and non-serrated flange nuts represents a fundamental engineering decision. Non serrated flange nuts—characterized by a seamless, flat flange integrated with a standard hex nut body—act as a high-integrity, unified fastener-washer system.

300,000+

Metric Tonnes Shipped

100+

Global Tier-1 Partners

10+

Years Engineering Expertise

ISO/DIN

Standard Compliance

Surface Protection & Anti-Galling

Unlike serrated alternatives that actively bite into the substrate and tear protective coatings, non serrated flange nuts apply smooth, uniform compression. This proves indispensable when fastening painted sheet metals, hot-dip galvanized steel, powder-coated enclosures, and anodized aluminum profiles, preventing galvanic acceleration and premature rust.

Precision Clamping Load Distribution

The widened bearing area minimizes localized contact stress over oversized, slotted, or misaligned clearance holes. By dissipating tension over an expanded footprint, these fasteners eliminate the requirement for separate loose flat washers, cutting component counts and slashing assembly line labor cycle times by up to 28%.

Predictable Torque-Tension Relationship

Serrations cause friction variations during seating, resulting in erratic clamp loads. Non serrated flange nuts deliver consistent nut factor (K-factor) coefficients. This stability allows torque-controlled multi-spindle automated assembly tooling to achieve pinpoint bolt preloads without thread damage or stripping.

Technical Matrix

Standard Specification Matrix: Non-Serrated Flange Nuts

Manufactured according to DIN 6923, ISO 4161, and ASME B18.16.4M dimensional profiles, compatible across industrial fastening operations worldwide.

Metric Nominal Thread	Pitch (Standard Metric)	Flange Diameter (dc max)	Width Across Flats (s max)	Overall Height (m max)	Proof Load Class 8 (kN)	Proof Load Class 10 (kN)
M5	0.8 mm	11.80 mm	8.00 mm	5.00 mm	12.2 kN	14.8 kN
M6	1.0 mm	14.20 mm	10.00 mm	6.00 mm	17.2 kN	20.9 kN
M8	1.25 mm	17.90 mm	13.00 mm	8.00 mm	31.8 kN	38.1 kN
M10	1.5 mm	21.80 mm	15.00 mm	10.00 mm	50.5 kN	60.3 kN
M12	1.75 mm	26.00 mm	18.00 mm	12.00 mm	74.2 kN	88.5 kN
M16	2.0 mm	34.50 mm	24.00 mm	16.00 mm	141.0 kN	168.0 kN

Field Deployment

Sector-Specific Engineering Application Scenarios

How global procurement leaders and structural designers leverage non serrated flange nuts across high-demand industrial installations.

Solar Photovoltaic Tracker & Racking

In single-axis tracker torque tubes and extruded aluminum rails, serrated nuts scratch anodized and zinc-aluminum-magnesium (ZAM) coatings, accelerating rust. Non serrated flange nuts distribute clamping evenly across thermal expansion slotted holes without biting through coatings, maintaining cathodic protection integrity for 25+ years.

Automotive Powertrain & EV Battery Enclosures

Aluminum battery enclosures and automotive subframes demand smooth seating surfaces to avoid localized micro-cracking and galvanic corrosion. Using stainless steel (A2/A4) or geometrically coated Class 10 non-serrated flange nuts ensures stable clamping across variable dynamic vibration loads.

Industrial HVAC & Prefabricated Steel Frames

Modular building and ductwork systems require swift connection speeds. With broad integrated washers, workers can secure connections without holding loose washers behind slotted bracket holes, optimizing site assembly speeds across high-wind seismic assemblies.

Forward Outlook

Fastener Technology Roadmap: Advancing Surface Science & Preload Control

The fastener industry is evolving beyond traditional hot-dip galvanizing and electro-zinc plating toward eco-friendly, ultra-durable thin-film passivation technologies.

Phase 1: Zinc Flake & Geomet Coatings

Eliminating hydrogen embrittlement risks in high-tensile Class 10.9 assemblies. Non-electrolytic zinc flake coatings supply 1,500+ hours of ASTM B117 salt spray endurance without thick thread build-up, maintaining free thread engagement on automated feeding systems.

Phase 2: Integrated Friction-Modifier Topcoats

Integrating synthetic wax-based lubricated topcoats directly over the non-serrated flange face. This guarantees a tightly controlled coefficient of friction (μ = 0.10 – 0.16), standardizing tightening torque accuracy on critical installations.

Phase 3: Smart Fastener Cold-Forming

Utilizing high-speed 6-station progressive cold-forging presses coupled with in-line eddy current crack detection and optical vision sorting, guaranteeing a defect rate below 50 PPM for automated robotic assembly lines.

Macro Solutions

Enterprise Supply Chain Resilience: Direct-from-Source Procurement

Handan Youlong Fastener Co., Ltd. sits in the heart of Yongnian District, China's Fastener Capital. We provide end-to-end manufacturing, custom drawing adaptation, and full traceability for international engineering contractors, wholesalers, and OEMs.

Vertical Steel Supply Integration

Direct supply partnerships with major regional steel mills ensure tight control over raw carbon steel rod (10B21, 35K, 45#) and stainless coils (304/316), shielding our partners from global spot-market price volatility and raw material delays.

Exacting Quality & In-House Lab Testing

Every production lot undergoes rigorous mechanical testing: Rockwell hardness (HRC), Vickers microhardness, tensile and proof load testing, alongside cyclic salt-spray corrosion chamber evaluations to ensure 100% standard compliance before shipment.

Comprehensive Documentation & Traceability

Full EN 10204 3.1 Mill Test Certificates (MTC), chemical spectrometry breakdowns, coating thickness x-ray reports, and Certificate of Origin documents accompany every sea and intermodal rail shipment.

Expert Answers

Frequently Asked Questions: Non Serrated Flange Nuts

Essential technical, manufacturing, and procurement guidance for mechanical engineers and supply chain directors.

What is the primary operational difference between serrated and non serrated flange nuts?

Serrated flange nuts have angled teeth on the flange face designed to bite into mating surfaces to resist vibration loosening. However, this damages surface treatments (coatings, paints, galvanizing) and causes erratic friction coefficients. Non serrated flange nuts feature a smooth underside that distributes clamping loads without scratching coatings, making them the preferred choice for painted surfaces, thin-gauge sheet metal, soft alloys like aluminum, and assemblies utilizing calibrated torque settings.

When should engineers specify a non serrated flange nut instead of a standard hex nut and separate washer?

A non-serrated flange nut should be specified whenever you want to eliminate loose washer inventory, reduce assembly labor, and avoid the risk of washers being omitted during field installations. The integrated flange ensures concentricity, provides a larger bearing diameter, and prevents the washer from cupping under extreme bolt preloads.

What steel grades and material alloys are available for volume manufacturing?

We manufacture non-serrated flange nuts in Class 8, Class 10, and Class 12 carbon and alloy steels (heat-treated quench and temper), as well as austenitic stainless steels (AISI 304 / A2-70, AISI 316 / A4-80) for marine and chemical processing environments. Custom copper-nickel and specialized brass configurations are also available upon request.

What surface treatments provide the best corrosion protection for outdoor solar structures?

For extreme outdoor durability, non-electrolytic zinc flake coatings (such as Geomet or Magni) or hot-dip galvanizing (HDG) are standard recommendations. Zinc flake coatings offer over 1,000 to 1,500 hours of salt spray resistance without the risk of hydrogen embrittlement, maintaining clean thread tolerances without requiring post-tapping rework.

How can overseas buyers verify factory compliance and inspect batches prior to dispatch?

Handan Youlong Fastener supports comprehensive third-party inspection agencies (including SGS, BV, and TÜV). We provide complete in-house inspection test reports covering chemical composition, thread ring gauge testing (6H standard), tensile proof load tests, coating thickness, and salt spray exposure data.

Associated Product Lines

High-Integrity Fasteners, Anchor Bolts & Structural Hardware

Complete structural assembly packages available for utility solar fields, prefabricated commercial warehouses, and heavy engineering facilities.