DIN 6914: High-Strength Structural Bolts
Equivalent Standard:
IS 3757 | ASTM A325 | EN 14399-4
DIN 6914 Heavy Hex Structural Bolts specifies high-strength hexagon head bolts with large widths across flats, primarily used in structural steel applications where high preload and shear resistance are required. These bolts are commonly paired with DIN 6915 (heavy hex nuts) and DIN 6916 (hardened washers).
DIN 6914 specifies dimensional, material, and mechanical requirements for high-strength hexagon head bolts used in structural steel connections requiring preloading. Heavy Hexagon Structural Bolts ideal for steel-to-steel structural connections, Heavy Hexagon Structural Bolts are a hex head bolt with a larger head and a shorter thread length than a regular hex head cap screw.
Common applications include:
Steel construction (buildings, bridges)
Crane and heavy machinery assembly
High-stress bolted joints
Key Takeaways
- DIN 6914 bolts are 9-grade structural bolts with reduced shanks
- Always used with DIN 6915 nuts and DIN 6918 washers
- Superseded by EN 14399-4 but still found in existing structures.
- Critical for slip-resistant connections in steel construction
- Reduced shank diameter(compared to standard bolts).
- DIN 6914
- Material Grade: 8.8, 10.9
- Finish: BZP, Hot Dip Galvanization
- Thread: METRIC
DIN 6914
Din 6914 Hex Bolt is made up of medium carbon alloy steel, medium carbon steel or low carbon steel materials. Superseded by EN 14399-4 but still found in existing structures & Standard DIN 6914.
DIN 6914 is used in preload assemblies, so the strength and corrosion resistance of all the bolts in the assembly have to be compatible. The En 14399-4 Hex Bolt is mostly made up of a property class 10.9 steel material.
These bolts exhibit good wear resistance as well.
3. Mechanical Properties of DIN 6914 ( Now Follows 14399-4 )
Property | Requirement |
Tensile Strength (Rm) | 1000-1200 MPa |
Yield Strength (Rp0.2) | ≥900 MPa |
Elongation (A) | ≥9% |
Preload (Fp,C) | See EN 14399-4 |
. Compatible Components
Component | Standard | Purpose |
Nuts | DIN 6915 | High-strength nuts (10H) |
Washers | DIN 6918 | Hardened washers (HR) |
Key Features
Material Grade: 10.9 (Yield strength ≥ 900 MPa, Tensile strength 1000-1200 MPa)
Head Design: Oversized hexagon head (larger than standard bolts) for better wrench grip
Surface Treatment: Typically hot-dip galvanized (≥50µm) or Dacromet-coated for corrosion resistance
Thread Type: Full or partial thread (shank length varies)
Preload Class: HV (High Preload) for structural applications
Equivalent StandardsISO 7412 (similar high-strength structural bolts)
ASTM A325/A490 (US equivalents, but different dimensions)
EN 14399-4
DIN 6914 bolts are premium structural Bolt for high-load applications where reliability is critical. Proper installation (torque + preload control) is essential for performance.
Technical Specification for High Strength Structural Bolts (DIN 6914)
| Nominal size and thread diameter d | Pitch of thread P | Thread Length b | Depth of washer face c | Transition diameter da | Diameter of unthreaded shank ds | Diameter of washer face dw | Width across corners e | Thickness of head k | Radius under head r | Width across flats s | ||||
| coarse pitch | Bolt ≤125 | min. | max. | min. | min. | max. | min. | min. | min. | max. | min. | min. | max. | |
| M12 | 1.75 | 23 | 0.4 | 0.6 | 15.20 | 11.30 | 12.70 | 20.10 | 23.91 | 7.55 | 8.45 | 1.2 | 21.16 | 22.00 |
| M16 | 2.00 | 28 | 0.4 | 0.6 | 19.20 | 15.30 | 16.70 | 24.90 | 29.56 | 9.25 | 10.75 | 1.2 | 26.16 | 27.00 |
| M20 | 2.50 | 33 | 0.4 | 0.8 | 24.00 | 19.16 | 20.84 | 29.50 | 35.03 | 12.10 | 13.90 | 1.5 | 31.00 | 32.00 |
| M22 | 2.50 | 34 | 0.4 | 0.8 | 26.00 | 21.16 | 22.84 | 33.30 | 39.55 | 13.10 | 14.90 | 1.5 | 35.00 | 36.00 |
| M24 | 3.00 | 39 | 0.4 | 0.8 | 28.00 | 23.16 | 24.84 | 38.00 | 45.20 | 14.10 | 15.90 | 1.5 | 40.00 | 41.00 |
| M27 | 3.00 | 41 | 0.4 | 0.8 | 32.00 | 26.16 | 27.84 | 42.80 | 50.85 | 16.10 | 17.90 | 2.0 | 45.00 | 46.00 |
| M30 | 3.50 | 44 | 0.4 | 0.8 | 35.00 | 29.16 | 30.84 | 46.60 | 55.37 | 17.95 | 20.05 | 2.0 | 49.00 | 50.00 |
| M36 | 4.00 | 52 | 0.4 | 0.8 | 41.00 | 35.00 | 37.00 | 55.90 | 66.44 | 21.95 | 24.05 | 2.0 | 58.80 | 60.00 |