EN 14399-3(HV System) Heavy Hex Bolt And Nut
The EN14399 HEAVY HEX BOLT is a high-strength structural fastener manufactured in strict accordance with the European standard EN 14399, specifically designed for preloaded structural bolting assemblies in steel construction. This standard covers high-strength structural bolts and nuts with large width across flats, and is classified into two main systems: System HV and System HRC. The heavy hex bolt features a larger and thicker head than standard hex bolts, providing an enlarged bearing surface that effectively distributes clamping forces and prevents embedding or indentation of connected steel members under extreme preload. These bolts are available in property classes 8.8, 10.9, and 12.9, with diameters ranging from M12 to M36, and are widely used in critical infrastructure projects such as bridges, high-rise buildings, stadiums, wind turbine towers, and heavy industrial facilities across Europe and beyond.
The Hot-dip galvanizing treatment EN14399-3 bolt refers specifically to the surface protection process applied to structural bolts to meet the requirements of heavy corrosion protection. This treatment involves immersing the bolt in a bath of molten zinc at temperatures around 450°C (850°F), creating a metallurgical bond between the zinc coating and the steel substrate. The resulting coating thickness typically ranges from 40 to 100 microns, providing exceptional corrosion resistance that can last for decades even in aggressive environments. Importantly, EN 14399-3 specifies that bolts with hot-dip galvanized coatings are only applicable for assemblies with controlled preload under specific conditions, as the coating thickness can affect thread fit and friction characteristics. Proper lubrication is therefore essential to achieve consistent preload values.
As a Hot-dip galvanized (EN ISO 10684) product, this bolt fully complies with the international standard for hot-dip galvanized coatings on threaded fasteners. EN ISO 10684 specifies the coating thickness requirements, quality levels, and inspection methods for galvanized fasteners, ensuring that the zinc coating provides both barrier and cathodic protection to the underlying steel. This standard mandates a minimum coating thickness of 40 microns for threads up to M20, and 55 microns for larger sizes, with specific requirements for thread over-tapping to accommodate the coating thickness while maintaining acceptable thread fit. These galvanized bolts are essential for outdoor structures, marine environments, chemical plants, and infrastructure projects where long-term corrosion resistance is critical. All products are supplied with complete test reports including coating thickness verification, adhesion testing, and thread gauge inspection.
