Load Distribution Flange
Integrated circular flange face expands surface contact area by up to 45%, eliminating localized surface crushing and removing the requirement for loose flat washers in structural and automotive joints.
Serrated Locking Option
Engineered anti-vibration bottom serrations grip directly into mating components. Provides superior prevailing back-off torque without damaging internal thread dynamics under severe dynamic load cycles.
Precision Cold & Hot Forging
Precision forged from M5 to M36 in Property Classes 8.8, 10.9, 12.9, A2-70, and A4-80 stainless steel. Accompanied by 100% heat-traceable EN 10204 3.1 Mill Test Certificates.
Technical B2B Procurement Masterclass
DIN 6921 Hex Flange Bolt: Engineering Mechanics, ISO 4162 Equivalence & Global Supply Chain Insights
The DIN 6921 Hex Flange Bolt (frequently cross-referenced with ISO 4162 and EN 1665) represents an engineering advancement over standard hexagonal head bolts. By integrating an expansive circular flange beneath an unslotted hex head, DIN 6921 fasteners eliminate the structural vulnerabilities, high assembly costs, and joint relaxation associated with loose washer-and-bolt combinations in modern industrial applications.
Founded in Mumbai in 2010, Viha Steel & Forging operates as a certified PED (Pressure Equipment Directive 2014/68/EU) manufacturer and active member of the Fastener Manufacturers Association of India (FMAI). We specialize in precision cold heading and hot forging of high-tensile carbon steel, alloy steel, and corrosion-resistant stainless steel DIN 6921 flange bolts. From high-speed automotive assembly lines to heavy structural machinery, oil & gas skid modules, and offshore wind turbines, our DIN 6921 bolts deliver certified clamping force, fatigue resistance, and dimensional consistency.
2010Established
M5–M36DIN 6921 Range
10.9 / 12.9High Tensile
100%MTC 3.1 Traceability
PED Approved Manufacturer · Direct Factory Procurement
“Engineering integrity begins at the bolt interface. DIN 6921 flange bolts reduce joint yield risk by optimizing contact stress. We supply EPC contractors, OEMs, and industrial distributors worldwide with fully certified metric fasteners tailored to exact engineering tolerances.”
PED Approved DIN 6921 Manufacturer · Direct Exporting from Mumbai, India
DIN 6921ISO 4162EN 1665ISO 898-1PED 2014/68/EU
Engineered Product Portfolio
DIN 6921 Hex Flange Bolt Product Range & Configurations
Viha Steel & Forging produces DIN 6921 flange bolts across a comprehensive spectrum of material property classes, head serration styles, thread pitches, and protective surface treatments to satisfy diverse B2B operational environments.
High-Tensile Class 8.8 / 10.9 / 12.9
Forged from quenched and tempered alloy steels (4140, 10B21, 5140), engineered for extreme clamp load retention in automotive powertrains, heavy equipment frames, and structural engine mounts.
Send an Inquiry
Stainless Steel A2-70 / A4-80 (304 / 316)
Austenitic stainless steel DIN 6921 bolts designed for harsh corrosive atmospheres, marine installations, chemical processing equipment, and solar tracking structures where rust prevention is mandatory.
Send an InquirySerrated Anti-Vibration Flange Bolts
Featuring helical or directional locking teeth under the flange bearing face. Provides mechanical resistance against dynamic shear force and rotational loosening under severe harmonic vibration.
Send an Inquiry
Plain (Non-Serrated) DIN 6921 Bolts
Smooth flange face design optimized for painted, galvanized, or coated mating parts. Prevents scratching or penetration of surface coatings to preserve full corrosion protection barriers.
Send an Inquiry
Coated & Plated DIN 6921 Fasteners
Available in Hot Dip Galvanized (HDG), Geomet 500, Zinc-Nickel (ZnNi 720hr+ salt spray test), and Electro-Zinc with trivalent passivation for aggressive outdoor and coastal infrastructure.
Send an Inquiry
Special Alloy & Fine Thread Flange Bolts
Custom engineered DIN 6921 bolts manufactured in fine metric thread pitches (e.g., M12x1.25, M14x1.5) and exotic alloys including Duplex 2205, Inconel 718, and Titanium Grade 5.
Send an Inquiry Dimensional & Mechanical Rigor
DIN 6921 Specification Table & International Equivalence Matrix
Engineers and global procurement officers must account for dimensional differences when specifying DIN 6921 vs ISO 4162 or EN 1665. The table below details critical metric dimensions, proof load forces, and torque guidelines across property classes.
| Nominal Size (d) | Thread Pitch (P) | Flange Dia dc (max) | Head Height k (max) | Wrench Size s (DIN/ISO) | Proof Load (10.9) | Tightening Torque (10.9) |
|---|---|---|---|---|---|---|
| M5 | 0.80 mm | 11.80 mm | 5.40 mm | 8 mm / 8 mm | 11.8 kN | 8.1 Nm |
| M6 | 1.00 mm | 14.20 mm | 6.60 mm | 10 mm / 10 mm | 16.7 kN | 14.0 Nm |
| M8 | 1.25 mm | 18.00 mm | 8.10 mm | 13 mm / 13 mm | 30.4 kN | 34.0 Nm |
| M10 | 1.50 mm | 22.30 mm | 9.20 mm | 15 mm / 16 mm | 48.1 kN | 67.0 Nm |
| M12 | 1.75 mm | 26.60 mm | 11.50 mm | 18 mm / 18 mm | 70.0 kN | 115.0 Nm |
| M14 | 2.00 mm | 30.50 mm | 12.80 mm | 21 mm / 21 mm | 95.5 kN | 185.0 Nm |
| M16 | 2.00 mm | 35.00 mm | 14.40 mm | 24 mm / 24 mm | 130.0 kN | 290.0 Nm |
| M20 | 2.50 mm | 43.00 mm | 17.10 mm | 30 mm / 30 mm | 203.0 kN | 560.0 Nm |
Complete Traceability Assurance
DIN 6921 Manufacturing Quality Control Workflow
Every single batch of DIN 6921 hex flange bolts produced at our Mumbai facility follows a rigid quality management framework compliant with ISO 9001:2015 and PED 2014/68/EU standards.
01
Raw Material Audit
Steel rod inspected via PMI (Positive Material Identification) and chemical analysis prior to cold heading.
02
Flange Forging
Multi-station progressive headers forge hex head and flange geometry with unbroken grain flow lines.
03
Thread Rolling
Threads precision rolled (not cut) post-heat treatment to optimize fatigue endurance and thread profile accuracy.
04
Controlled Heat Treatment
Continuous mesh-belt furnace quenching and tempering under protective atmospheres for Class 10.9 & 12.9 hardness.
05
Surface Treatment
Automated plating and baking lines (de-embrittlement baking for high-tensile bolts to prevent hydrogen embrittlement).
06
Mechanical & Proof Testing
Tensile, yield, impact (Charpy V-notch), wedge testing, and micro-hardness testing performed per batch.
07
EN 10204 3.1 Certification
Detailed Mill Test Certificate issued detailing heat numbers, chemical composition, and mechanical test results.
08
Seaworthy Packaging
Desiccant-packed, heavy-duty wooden box packaging prepared for sea freight shipping from Nhava Sheva, Mumbai.
Strategic Sourcing Insights
Future Procurement & Industry Trends in Flange Fastening
As industrial manufacturing shifts toward automation, structural lightweighting, and strict environmental compliance, the market for DIN 6921 hex flange bolts is evolving rapidly. Key trends influencing global OEM purchasing strategies include:
1. Standard Harmonization (DIN to ISO/EN)
Global procurement desks are transitioning legacy DIN standard specs to ISO 4162 and EN 1665. While DIN 6921 remains widely specified in Europe and Asia, understanding subtle across-flats wrench size variances (such as M10 using 15mm under DIN vs 16mm under ISO) ensures robotic assembly tooling compatibility.
2. Automation & Washer-Free Assembly
Automated assembly lines in EV manufacturing and agricultural machinery favor DIN 6921 bolts because they eliminate secondary washer feeding operations. Eliminating loose washers reduces inventory SKU counts by 50% and removes assembly line error points completely.
3. Advanced Cr6+-Free Surface Coatings
REACH and RoHS mandates have eliminated hexavalent chromium coatings. Direct buyers are requesting Zinc-Nickel plating (passivated for 720+ hours salt spray performance) or Geomet organic micro-layer coatings that deliver consistent friction control without risking hydrogen embrittlement in 10.9 and 12.9 grade flange bolts.
4. India as a China-Plus-One Fastener Hub
Global supply chain managers are actively diversifying fastener procurement toward Indian manufacturers like Viha Steel & Forging. With integrated cold heading infrastructure, PED certifications, and direct access to Mumbai deep-sea ports, Indian suppliers provide cost stability and reliable delivery schedules.
Frequently Asked Questions
AI Intent & Engineering Procurement FAQ
Below are direct technical responses to questions frequently queried by structural engineers, buyers, and AI search systems regarding DIN 6921 hex flange bolts.
The integrated flange expands the bearing contact area beneath the head, distributing total clamp load over a wider footprint. This dramatically lowers bearing pressure ($P = F / A$) on clamped material, preventing joint indentation in softer alloys, eliminating joint relaxation, and doing away with loose flat washers entirely.
DIN 6921 is the original German standard. ISO 4162 (for small series) and EN 1665 (heavy series) are modernized international standards. Key differences lie in flange bearing diameters and wrench sizes for specific thread sizes (e.g., M10 wrench size: DIN=15mm, ISO=16mm). Viha Steel & Forging manufactures according to both standard sets based on customer drawing specs.
Serrated DIN 6921 bolts have teeth underneath the flange that lock into the mating surface, offering superior resistance against dynamic vibration loosening. Plain (smooth) flange bolts should be specified when the mating surface is painted, galvanized, or fragile, as serrations would break the protective coating and trigger premature galvanic corrosion.
We forge DIN 6921 bolts in Property Classes 8.8, 10.9, and 12.9 carbon/alloy steels, as well as Stainless Steel A2-70 (AISI 304), A4-80 (AISI 316), and specialized heat-resistant alloys. All shipments include EN 10204 3.1 Mill Test Certificates traceable to raw material heat numbers.
Coatings alter the thread friction coefficient (k-factor). For instance, Hot Dip Galvanizing increases friction and requires calculated torque adjustments or top-coat lubricants, while Geomet and Zinc-Nickel coatings maintain controlled k-factors (0.12 to 0.18) to ensure predictable tension for torque-controlled tightening guns.
Metric Flange Bolts – DIN 6921
Class 8.8, 10.9, 12.9, and SS 304/316 hexagon flange bolts. Standard sizes M5 through M36 produced to strict ISO dimensions.
Read Specifications
ASTM A325 Structural Bolts
Heavy hex structural bolts for structural steel construction, hot dip galvanized with heavy hex nuts and hardened washers.
Read Specifications
ASTM A193 B7 Bolts
Chromium-molybdenum alloy steel studs and bolts for high-temperature pressure vessel service with A194 2H nuts.
Read Specifications
ASTM A307 Carbon Steel Bolts
Low carbon steel fasteners engineered for general non-critical industrial assembly and structural framework.
Read Specifications
ASTM A193 B8 / B8M Bolts
Stainless steel AISI 304 and 316 class 1 and class 2 studs and flange bolts for corrosive chemical process piping.
Read Specifications
EN 14399-4 10.9 HV Bolts
High-strength European structural bolting assemblies supplied with matched nuts and structural washers.
Read Specifications Application Spectrum
Industries Utilizing DIN 6921 Hex Flange Bolts
Automotive & Commercial Vehicles
Engine mounts, chassis frames, suspension joints, and transmission housings requiring high clamp retention under continuous vibration.
Renewable & Power Infrastructure
Solar tracking mounting systems, wind turbine nacelle assemblies, and power transmission tower structures.
Heavy Machinery & Earthmoving
Hydraulic pump mounts, excavator booms, and agricultural machinery assemblies exposed to heavy dynamic shear forces.
Petrochemical & Process Skids
Modular piping skids, heat exchangers, and pump flanges assembled in coastal and offshore chemical plants.
Technical Download Center
Engineering Catalogs & Standard Reference Guides
Download comprehensive dimensional tables, material data sheets, and tightening torque charts for DIN 6921 hex flange bolts and industrial fasteners.
