EN 14399-1 Standard defines pre-loaded high-strength structural bolted connections and general requirements. It sets technical criteria to ensure the safe and solid operation of the connection elements. High-strength connection elements play a critical role, especially in systems carrying heavy loads. EN 14399-1 regulates the design, production, and use of these elements.
EN 14399-1 specifies all the technical requirements necessary to manufacture connection elements resistant to various loads and pressures. Connection elements made in compliance with this standard perform well and maintain their safety even in long-term use. Additionally, EN 14399-1 guarantees that the connection elements are resistant to various environmental impacts (corrosive environments, high temperatures, etc.).
Important notes about EN 14399-1:
High-strength structural bolting assemblies smaller than M12 are not designed to be preloaded.
High-strength structural bolting assemblies are not designed to be welded.
Railway rail fasteners are not covered by this standard.
The EN 14399 standard consists of the following sections under the general heading “Preloading for high-strength structural bolt assemblies”:
Part 1: General requirements;
Part 2: Suitability for preloading;
Part 3: System HR — Hexagon bolt and nut assemblies;
Part 4: System HV — Hexagon bolt and nut assemblies;
Part 5: Plain washers;
Part 6: Plain chamfered washers;
Part 7: System HR — Countersunk head bolt and nut assemblies;
Part 8: System HV — Hexagon fit bolt and nut assemblies;
Part 9: System HR or HV — Direct tension indicators for bolt and nut assemblies;
Part 10: System HRC — Bolt and nut assemblies with calibrated preload.
Feature Classess
Elongation (Bolts)
Tensile strength (Bolts)
Resistance under wedge loading (Bolts)
Yield strength (Bolts)
Test load (Bolts and Nuts)
Impact resistance (Bolts)
Hardness (Bolts, Nuts, Washers, and if applicable, Direct Tension Indicators)
Pressure load (Direct Tension Indicators)
Factory Production Control System (FPCS)
The manufacturing organization must establish a Factory Production Control System (FPCS) in accordance with the EN 14399-1 standard and must continuously apply this system. This system ensures that products undergo quality control at every stage.
The FPC system should include procedures, regular inspections, tests, and/or evaluations, and the use of these results to control raw materials and other incoming materials, components, equipment, production processes, and products. All elements, requirements, and provisions accepted by the manufacturer must be systematically documented in the form of written policies and procedures.
It is a system that integrates all necessary measures to maintain and control compliance with the operational techniques and fundamental characteristics of the declared product performance.
Test reports for preloaded high-strength structural bolted connections must be retained by the manufacturer for at least 10 years from the final production date. The manufacturer should establish procedures to ensure that the specified values of the declared characteristics are maintained. Acceptance criteria for incoming raw materials should be documented. All test equipment shall be calibrated according to documented procedures, frequencies and criteria. Personnel performing work affecting the performance of the product shall be competent based on appropriate education, training, skills and experience, and records shall be kept of this.
Preloaded high-strength structural bolted connections and their packaging should be identifiable and traceable in relation to their production. The manufacturer must plan and carry out production under controlled conditions.
The manufacturer must have written procedures specifying how non-conforming products should be handled. Non-conforming products must be recorded, and when products do not meet the acceptance criteria, necessary corrective actions must be immediately taken. Non-conforming products or batches must be isolated and properly identified.
Once the issue is corrected, the relevant test or validation must be repeated. Control and test results should be appropriately documented. Product description, production date, test method, test results, and acceptance criteria should be recorded under the signature of the person responsible for control/testing.
The manufacturer must have documented procedures for corrective actions to prevent repeated errors and eliminate the causes of non-conformities. They must have procedures for determining product handling methods and provide suitable storage areas to prevent damage or deterioration.
Preloaded high-strength structural bolted connections are subject to System 2+ conformity approval under the Construction Products Regulation (305/2011/EU) for CE marking.
You can apply to ATC International for certification of non-preloaded structural bolting connections according to EN 14399-1.
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