Product Introduction
Hexagon nut, property class 10, manufactured and CE‑marked to EN 14399‑4 for System HV (Hochfest Vorgespannt) preloaded bolting. The nut is part of a matched assembly that includes a property class 10.9 HV bolt and two through‑hardened washers to EN 14399‑6 (grade HV300). HV‑system nuts are supplied with a black surface treatment — black oxide, plain lubricated, or MoS₂‑treated — and are intended for preloaded structural joints designed to EN 1993‑1‑8. The reduced height and large across‑flats distinguish the HV nut from HR‑system components, and the complete assembly is mandatory from a single manufacturer to maintain CE certification.

Material & Mechanical Properties
Conforms to property class 10 per EN ISO 898‑2. Proof load stress is verified to EN 20898‑2. The system delivers ductility predominantly by controlled plastic deformation of the engaged thread flanks under preload. This behaviour ensures dependable tensioning and clear overload indication.

Dimensional Specifications & Thread

• Thread sizes: M12 to M36

• Nut height (m): approximately 0.8d (reduced, e.g. 20 mm for M24)

• Width across flats (s): enlarged per HV series (e.g. 41 mm for M24)

• Thread tolerance before zinc‑coat: 6AZ per ISO 965‑5, providing oversize to accept hot‑dip galvanizing where specified, while maintaining correct fit with 6H internal threads after coating.

• Mating bolt thread: length per ISO 888 to allow the required bolt elongation.

Surface Finish & Lubrication
The nut is supplied with a black surface finish as standard. For galvanized assemblies, MoS₂ (molybdenum disulphide) lubricant is applied after galvanizing; internal threads are not separately coated and rely on this lubricant for corrosion protection and a stable friction coefficient. The friction condition is designated K‑class K1 (torque control method), enabling reliable achievement of the specified preload of at least 0.7 × fub × As.

System HV Assembly & Compliance
Each assembly comprises:

• Bolt: EN 14399‑4, property class 10.9

• Nut: EN 14399‑4, property class 10

• Washers: two pieces EN 14399‑6, HV300, hardness 300–370 HV

CE marking under the Construction Products Regulation (CPR, System 2+) requires all three components to be supplied together by the same manufacturer as a traceable set. The nut carries a stamped production‑lot code on its face for batch identification. A 3.1 inspection certificate per EN 10204 is available if specified at the time of order.

Application Suitability
Preloaded bolted connections in steel structures — bridges, high‑rise frames, heavy industrial plant — where the HV system is specified for its compact nut envelope, controlled ductility through thread plasticity, and compatibility with torque‑controlled tensioning methods. Hot‑dip galvanized HV assemblies are used for outdoor and corrosive environments, with the black lubricant ensuring consistent preload during installation.