EN 14399 High-strength heavy-duty steel structure bolt assemblies
EN 14399 is a standard for high-strength structural bolted connection systems developed by the European Committee for Standardization (CEN). It is specifically designed for heavy-duty/high-strength bolted connections in industries such as industry and construction, and is one of the core product standards commonly used in European and global foreign trade.
EN 14399 specifies the technical requirements for bolted connections in high-strength steel structures. It is applicable to heavy structures subjected to dynamic loads, static loads, or seismic loads (such as bridges, factories, machinery, wind turbines, etc.) and is a core European standard for "heavy-duty bolts" (corresponding to the international standard ISO 898-1 high-strength grade).
EN 14399 Fastener Key Technical Features
EN 14399 Fastener Strength Grade:
Core Grades: 8.8, 10.9, 12.9 (Heavy-duty applications primarily use 10.9/12.9, tensile strength ≥1040MPa);
Material: Carbon steel or alloy steel (e.g., 42CrMo, 35CrMo), requiring heat treatment (quenching + tempering).
EN 14399 Fastener Connection Type:
Complete Set: Bolt + Nut + Washer (flat washer/spring washer, some requiring anti-loosening design);
Connection Type: Friction connection (relying on the friction force generated by bolt preload for force transmission), bearing connection (suitable for heavy-duty scenarios).
EN 14399 Fastener Dimensions:
Thread Specifications: M12~M36 (heavy-duty commonly uses M20~M30);
Bolt Length: Customized according to application scenario (usually 40~300mm);
Head Type: Hex head (most common, conforming to EN 14399-3), flange face hex head (anti-loosening and anti-slip).
EN 14399 Fastener Surface Treatment:
Standard Requirements: Hot-dip galvanizing (HDG, high corrosion resistance), electro-galvanizing, phosphating + oiling (suitable for dry indoor environments); Salt Spray Test: Hot-dip galvanized products typically require a salt spray test of ≥720 hours.
EN 14399 Fastener Differences from Other Standards
| Standard | Applicable Region | Core Differences | Application Scenarios Emphasis |
| EN 14399 | European and Overseas European Standard Market | Emphasizes compatibility and seismic resistance of complete sets of components | High-end heavy structures, foreign trade export |
| ISO 898-1 | Internationally Applicable | Only specifies the strength of a single bolt, no requirements for complete sets | General machinery, non-critical structures |
| GB/T 1231 | China | Revised according to ISO, adapted to domestic working conditions | Domestic construction and machinery industries |
| ASTM A325/A490 | USA | Different thread specifications and strength grade markings | North American market heavy structures |