EN 10225 Weldable structural steel pipes for fixed offshore structures

The European standard EN 10225 is a specialized standard for weldable structural steel used to secure offshore structures, covering the technical delivery conditions for steel plates, profiles, and steel pipes. This standard aims to ensure the safety, reliability, and durability of these steels in harsh marine environments. The following is a detailed interpretation of the EN 10225 standard, especially its content related to steel pipes:

1. Overview of Standards

The EN 10225 standard specifies the technical requirements for weldable structural steel used for fixing offshore structures, including chemical composition, mechanical properties, dimensional tolerances, inspection methods, etc. This standard applies to steel plates with a thickness not exceeding 150 millimeters, profiles with a large thickness of 63 millimeters, and hollow profiles (steel pipes) with seamless and high-frequency resistance welding.

2. Scope of application

-Steel pipe type: EN 10225 standard applies to seamless hollow profiles (steel pipes) and high-frequency resistance welded hollow profiles (steel pipes), with thicknesses not exceeding 40 millimeters and 20 millimeters, respectively.

-Application areas: Mainly used for fixing offshore structures such as offshore platforms, oil extraction equipment, dock facilities, etc., but not applicable to subsea pipelines, risers, and process equipment.

3. Technical requirements

3.1 Chemical Composition

-Steel pipes must comply with the chemical composition requirements specified in the standards, including content limits for elements such as carbon (C), manganese (Mn), silicon (Si), phosphorus (P), and sulfur (S). For example, the carbon content of S355NLO steel pipe does not exceed 0.18%, and the sulfur content does not exceed 0.02%.

-For high-strength steel grades (such as S460MLO), it is also necessary to control the content of microalloying elements (such as niobium, vanadium, titanium) to achieve good welding performance and corrosion resistance.

3.2 Mechanical Properties

-Yield strength: The small yield strength of steel pipes varies depending on their thickness. For example, when the thickness of S355NLO steel pipe does not exceed 50 millimeters, the small yield strength is 355 MPa; When the thickness exceeds 100 millimeters, the small yield strength is 335 MPa.

-Low temperature impact performance: Steel pipes need to have good impact toughness at low temperatures (such as -40 ° C) to cope with extreme conditions in marine environments.

3.3 Welding performance

-Steel pipes need to have good welding performance for safety and reliability in marine engineering. The standard provides clear requirements for welding processes, weld quality, and non-destructive testing (such as ultrasonic testing and magnetic particle testing).

3.4 Dimensions and tolerances

-The dimensions and tolerances of steel pipes must comply with relevant European standards (such as EN 10210-2) to ensure compatibility with joints and fittings.

4. Inspection and Testing

-Chemical composition analysis: Determine whether the chemical composition of the steel pipe meets the standard requirements through melting analysis.

-Mechanical performance testing: including tensile testing, impact testing, etc., to evaluate the yield strength, tensile strength, and low-temperature toughness of steel pipes.

-Non destructive testing: Ultrasonic testing, magnetic particle testing and other methods are used to detect defects such as cracks and inclusions inside steel pipes.

5. Application Cases

-Offshore platforms: Steel pipes in accordance with EN 10225 standard are widely used in key structural components of offshore platforms, such as support columns, decks, etc.

-Dock facilities: supporting structures and connecting components used for manufacturing dock equipment.

-Deep sea engineering: structural components suitable for deep-sea oil and gas development equipment, with good fatigue and corrosion resistance.

6. Comparison with other standards

-EN 10224: The EN 10224 standard is applicable to steel pipes used for water transportation, while EN 10225 focuses more on weldable structural steel for fixed offshore structures, with higher requirements for high strength, corrosion resistance, and low-temperature performance.

-EN 10210: The EN 10210 standard applies to hot-rolled hollow profiles, while EN 10225 adds special requirements for steel used in marine engineering on this basis.

(Note: Parameters may be adjusted due to engineering requirements;)