EN 14399-4 High-Strength Structural Bolts – HV 10.9 HDG
High-strength structural bolts with enlarged hexagon heads for preloaded steelwork joints. JENPEX supplies property class 10.9 bolts in hot-dip galvanized HDG finish, covering standard sizes M12 to M36.
Key ordering information
This is a high-strength structural bolt with an enlarged hexagon head for preloaded steelwork joints. The ranges below are standard or manufacturing ranges and do not imply that every size and length is held in stock.
Sizes, length ranges and socket sizes
| Size | Standard length range L | Property class | Finish | Socket / wrench size |
|---|---|---|---|---|
| M12 | 35–95 mm | 10.9 | HDG | 22 mm |
| M16 | 40–130 mm | 10.9 | HDG | 27 mm |
| M20 | 45–155 mm | 10.9 | HDG | 32 mm |
| M22 | 50–165 mm | 10.9 | HDG | 36 mm |
| M24 | 60–195 mm | 10.9 | HDG | 41 mm |
| M27 | 70–200 mm | 10.9 | HDG | 46 mm |
| M30 | 75–200 mm | 10.9 | HDG | 50 mm |
| M36 | 85–200 mm | 10.9 | HDG | 60 mm |
Available combinations are checked against the standard, manufacturing programme and requested quantity.
Which impact socket size do I need?
EN 14399-4 HV bolts have enlarged hexagon heads, so their wrench sizes differ from general-purpose DIN 931 / ISO 4014 and DIN 933 / ISO 4017 bolts. M16 requires 27 mm, M20 32 mm, M24 41 mm, M30 50 mm and M36 60 mm. The complete M12–M36 mapping is shown above.
For installation, JENPEX also offers forged impact sockets and impact adapters.
Applications
Typical applications include designed preloaded joints in industrial buildings, load-bearing steel frames, bridge structures, energy-sector structures and mechanical steel assemblies. The project and installation specification determine whether an HV assembly is required for a particular joint.
What does the HV system mean?
HV is a system of high-strength structural bolting assemblies for preloading in steel construction. EN 14399-4 defines HV hexagon bolt and nut assemblies with large widths across flats.
A complete HV assembly uses a compatible class 10.9 bolt and class 10 nut to EN 14399-4 (historically DIN 6915), together with the appropriate washer to EN 14399-6 (historically DIN 6916). Components should not be mixed without verifying assembly compatibility and manufacturer documentation.
EN 14399-4 and the historical DIN 6914 designation
The current designation is EN 14399-4, or its national adoption DIN EN 14399-4. DIN 6914 is a historical designation replaced by the European standard, but it remains common in drawings, older projects, purchase orders and commercial searches. ISO 7412 is withdrawn and is mentioned only as a historical reference, not as a current equivalent.
HV bolt vs. a general-purpose hexagon bolt
| Design | Characteristics |
|---|---|
| EN 14399-4 / DIN 6914 | HV system, property class 10.9 bolt, preloaded structural joints, enlarged head and larger width across flats. |
| DIN 931 / ISO 4014 | General-purpose hexagon-head bolt with partial thread. |
| DIN 933 / ISO 4017 | General-purpose hexagon-head bolt with full thread. |
These are different standardized and functional designs; project requirements determine the correct choice.
Bolt geometry
| Size d | P | b | ds | dw min. | e min. | k nom. | s / SW |
|---|---|---|---|---|---|---|---|
| M12 | 1.75 | 23 | 11.30–12.70 | 20.1 | 23.91 | 8 | 22 |
| M16 | 2.00 | 28 | 15.30–16.70 | 24.9 | 29.56 | 10 | 27 |
| M20 | 2.50 | 33 | 19.16–20.84 | 29.5 | 35.03 | 13 | 32 |
| M22 | 2.50 | 34 | 21.16–22.84 | 33.3 | 39.55 | 14 | 36 |
| M24 | 3.00 | 39 | 23.16–24.84 | 38.0 | 45.20 | 15 | 41 |
| M27 | 3.00 | 41 | 26.16–27.84 | 42.8 | 50.85 | 17 | 46 |
| M30 | 3.50 | 44 | 29.16–30.84 | 46.6 | 55.37 | 19 | 50 |
| M36 | 4.00 | 52 | 35.00–37.00 | 55.9 | 66.44 | 23 | 60 |
All dimensions are in mm. d = nominal thread diameter; P = thread pitch; b = reference thread length; ds = shank diameter; dw = bearing-face diameter; e = width across corners; k = head height; s / SW = width across flats or wrench size.
Property class 10.9
The EN 14399-4 HV bolt uses property class 10.9. Nominal tensile strength fub is approximately 1,000 MPa and the nominal yield-related value is approximately 900 MPa. The corresponding HV nut is class 10.
HDG means hot-dip galvanized. It is the surface finish supplied by JENPEX for this product group; it does not mean EN 14399-4 permits only HDG.
Nominal preload
The relationship Fp,C = 0.7 × fub × As is used, where Fp,C is the nominal preload, fub the nominal tensile strength and As the tensile stress area. For class 10.9, fub = 1,000 MPa in this calculation.
| Size | Tensile stress area As | Approx. Fp,C |
|---|---|---|
| M12 | 84.3 mm² | 59 kN |
| M16 | 157 mm² | 110 kN |
| M20 | 245 mm² | 172 kN |
| M22 | 303 mm² | 212 kN |
| M24 | 353 mm² | 247 kN |
| M27 | 459 mm² | 321 kN |
| M30 | 561 mm² | 393 kN |
| M36 | 817 mm² | 572 kN |
These values are nominal preloads from the stated relationship. They are not the maximum resistance of a joint, fracture load or allowable structural load.
Why is there no universal tightening-torque table?
Tightening torque depends on the specific assembly, K-class, lubrication, surface finish, preload method, installation specification and manufacturer documentation. Use the documented values and procedure for the selected compatible HV assembly rather than a universal Nm value.
Frequently asked questions
What is EN 14399-4?
It is the standard for high-strength structural bolting assemblies for preloading, system HV, with hexagon bolt and nut assemblies in sizes M12 to M36.
Is DIN 6914 still a current standard?
DIN 6914 is a historical designation replaced by EN 14399-4, but it remains common in drawings, orders and older projects.
Which HV bolt sizes are covered?
M12, M16, M20, M22, M24, M27, M30 and M36, with standard length ranges shown in the main table.
Which impact socket size do I need?
Depending on the bolt size, use 22, 27, 32, 36, 41, 46, 50 or 60 mm. M24 uses 41 mm, M30 uses 50 mm and M36 uses 60 mm.
What does property class 10.9 mean?
It identifies a high-strength bolt with a nominal tensile strength of approximately 1,000 MPa and a nominal yield-related value of approximately 900 MPa.
What makes up a complete HV assembly?
A compatible class 10.9 bolt and class 10 nut to EN 14399-4 together with the appropriate washer to EN 14399-6.
Need a quotation for EN 14399-4 HV bolts or complete HV bolting assemblies?
Send us the required size, length, quantity and application details. We will verify the suitable configuration and prepare a B2B quotation.
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