What are the main standards governing structural bolts?
Structural bolts are regulated by a series of international and national technical standards that define the mechanical characteristics, dimensional tolerances, performance requirements, and testing methodologies. These standards ensure that the bolts used in construction and infrastructure are safe and reliable. Below are some of the main standards that govern structural bolts:
European Standards (EN)
EN 14399 - High-strength structural bolting assemblies for preloading:
- This standard defines the requirements for high-strength structural bolts used for preloading. It includes specifications for bolts, nuts, and washers, as well as testing methodologies to ensure the components meet structural needs.
- It is divided into several parts, each covering specific aspects such as dimensions, materials, surface treatments, and tightening methods.
EN 15048 - Non-preloaded structural bolting assemblies:
This standard covers non-preloaded structural bolts used in connections that do not require the application of significant tightening load. The standard specifies the mechanical characteristics and performance requirements for bolts, nuts, and washers.
EN 1090 - Execution of steel structures and aluminium structures:
Although not specifically a standard for bolts, EN 1090 governs the execution of steel and aluminium structures, including requirements for the use of structural bolts, assembly quality, and certifications required for components.
International Standards (ISO)
ISO 898-1 - Mechanical properties of fasteners made of carbon steel and alloy steel:
This standard specifies the mechanical properties of carbon steel and alloy steel bolts. It covers the most common strength classes used in structural bolting, such as 8.8, 10.9, and 12.9, and defines performance requirements such as tensile strength and hardness.
ISO 4014 - Hexagon head bolts - Product grades A and B:
This standard specifies the dimensions and tolerances for hexagon head bolts with metric threads, ensuring compatibility and interchangeability between components used internationally.
ISO 4032 - Hexagon nuts, Style 1 - Product grades A and B:
This standard defines the dimensional and tolerance specifications for hexagon nuts used with structural hexagon head bolts, ensuring a secure and reliable fit.
American Standards (ASTM)
ASTM A325 - Standard Specification for Structural Bolts, Steel, Heat Treated, 120/105 ksi Minimum Tensile Strength:
- This standard specifies the requirements for heat-treated steel structural bolts used in applications such as bridge and building construction. It covers mechanical properties and testing requirements to ensure the bolts' strength and durability.
ASTM A490 - Standard Specification for Structural Bolts, Alloy Steel, Heat Treated, 150 ksi Minimum Tensile Strength:
A similar standard to ASTM A325, but for high-strength alloy steel bolts, with a higher minimum tensile strength. These bolts are used in critical applications requiring greater mechanical strength.
ASTM F3125 - Standard Specification for High Strength Structural Bolts, Steel and Alloy Steel, Heat Treated, 120 ksi (830 MPa) and 150 ksi (1040 MPa) Minimum Tensile Strength, Inch and Metric Dimensions:
This standard unifies several previous specifications (including A325 and A490) to create a comprehensive standard for high-strength structural bolts in both inch and metric dimensions.
Italian Standards (UNI)
UNI 5737 - Hexagon head bolts - Shape C (for metal structures):
This standard defines the dimensions and specifications for hexagon head bolts intended for metal structures according to Italian standards.
UNI 5712 - High hexagon nuts - Shape 1 (for metal structures):
Specifies the requirements for hexagon nuts used with hexagon head bolts in metal structures, including those intended for structural connections.
These standards are essential to ensure that structural bolting products are safe, reliable, and meet the required standards for construction projects and infrastructure. Compliance with these standards is often required in contract specifications and quality control checks to ensure the safety of the completed works.
