EN10225 Grade S355G3+N Offshore Steel Plate
EN10225 Grade S355G3+N Offshore Steel Plate - Properties & Equivalents
Comprehensive material data for EN10225 Grade S355G3+N offshore structural steel plate including chemical composition, mechanical properties, physical properties, and equivalent grades.
Hot rolling, Normalizing (+N), Welding, Cold forming, Cutting
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EN10225 Grade S355G3+N Offshore Steel Plate Introduction
S355G3+N is a high-strength weldable structural steel plate designed for fixed and mobile offshore structures in accordance with European standard EN 10225. It is delivered in the normalized condition (+N) to guarantee a fine-grain microstructure and consistent mechanical properties. The grade offers a minimum yield strength of 355 MPa for thicknesses up to 40 mm and excellent notch toughness at -40 °C. Key features include:
- Low carbon equivalent (CEV) for superior weldability without preheat in moderate sections
- Strict control of sulfur and phosphorus for improved ductility and toughness
- Full through-thickness property reliability suitable for demanding marine environments
- Approved for use under major classification societies (DNV, ABS, LR) when traceability and additional testing are applied
EN10225 Grade S355G3+N Offshore Steel Plate Chemical Composition
Chemical composition limits according to EN 10225:2009 for S355G3. Carbon equivalent CEV is also controlled to ensure excellent weldability. Values correspond to the ladle analysis.
| Chemical Element | Standard Value | Remarks |
|---|---|---|
| Carbon (C) | ≤0.18 | Max |
| Silicon (Si) | 0.10 - 0.50 | |
| Manganese (Mn) | 1.00 - 1.65 | |
| Phosphorus (P) | ≤0.020 | Max |
| Sulfur (S) | ≤0.010 | Max |
| Chromium (Cr) | ≤0.25 | Max |
| Nickel (Ni) | ≤0.50 | Max |
| Molybdenum (Mo) | ≤0.10 | Max |
| Copper (Cu) | ≤0.35 | Max |
| Aluminum (Al) | ≥0.015 | Min, total aluminum, for grain refinement |
| Niobium (Nb) | ≤0.05 | Max |
| Vanadium (V) | ≤0.12 | Max |
| Titanium (Ti) | ≤0.05 | Max |
| Nitrogen (N) | ≤0.012 | Max |
| Carbon equivalent (CEV) | ≤0.43 | For thickness ≤ 40 mm, CEV = C + Mn/6 + (Cr+Mo+V)/5 + (Ni+Cu)/15 |
EN10225 Grade S355G3+N Offshore Steel Plate Thermal and Electrical Physical Properties
Physical properties for structural steels such as S355G3. These values are indicative for design calculations based on EN 1993-1-1 and common engineering practice.
| Performance Item | Standard Required Value | Unit | Test Conditions |
|---|---|---|---|
| Density (ρ) | 7850 | kg/m³ | At 20 °C |
| Modulus of elasticity (E) | 210 000 | MPa | At 20 °C |
| Shear modulus (G) | 81 000 | MPa | At 20 °C |
| Poisson's ratio (ν) | 0.3 | - | Elastic range |
| Thermal expansion coefficient (α) | 12 × 10-6 | /K | 20 °C - 100 °C |
| Thermal expansion coefficient (α) | 13 × 10-6 | /K | 20 °C - 200 °C |
| Thermal conductivity (λ) | 50 | W/(m·K) | At 20 °C |
| Specific heat capacity | 460 | J/(kg·K) | At 20 °C |
| Electrical resistivity (ρe) | 0.20 × 10-6 | Ω·m | At 20 °C |
EN10225 Grade S355G3+N Offshore Steel Plate Mechanical Properties
Mechanical properties per EN 10225:2009 for S355G3+N. Tensile and impact tests are performed on transverse and longitudinal samples respectively. Charpy V-notch impact energy requirements are given for -40 °C.
| Performance Item | Standard Required Value | Unit | Test Conditions |
|---|---|---|---|
| Yield strength (ReH) | 355 | MPa | Thickness ≤ 40 mm |
| Yield strength (ReH) | 345 | MPa | 40 mm < Thickness ≤ 63 mm |
| Yield strength (ReH) | 335 | MPa | 63 mm < Thickness ≤ 80 mm |
| Yield strength (ReH) | 325 | MPa | 80 mm < Thickness ≤ 100 mm |
| Tensile strength (Rm) | 470 - 630 | MPa | Thickness ≤ 100 mm |
| Elongation (A) | 22 | % | Gauge length 5.65√So, thickness ≤ 40 mm |
| Elongation (A) | 21 | % | 40 mm < Thickness ≤ 63 mm |
| Elongation (A) | 20 | % | 63 mm < Thickness ≤ 100 mm |
| Impact energy (KV) at -40 °C | 50 | J | Longitudinal, average of 3 tests, min. single 35 J |
| Bend test (mandrel diameter) | 3t | - | Through 180° (t = plate thickness), no cracks |
EN10225 Grade S355G3+N Offshore Steel Plate Full Equivalent Material Standards & Substitute Grades
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| Europe | EN 10225:2009 | S355G3+N | Original designation |
| United Kingdom | BS 7191 | 355EMZ | Withdrawn, but historically equivalent for offshore steel |
| International | ISO 19902 | S355G3 | For fixed steel offshore structures; +N condition available |
| USA | API 2H | Grade 50 | Offshore structural plate, similar strength and toughness requirements |
| Norway | NORSOK M-120 | Y35 | Standard for offshore structural steel, equivalent to S355G3 |
EN10225 Grade S355G3+N Offshore Steel Plate Application Introduction
S355G3+N steel plate is engineered for offshore structural applications demanding high strength, excellent weldability, and good low-temperature toughness. The normalized condition guarantees a fine-grained microstructure and consistent properties throughout the thickness. Key uses encompass:
- Fixed and mobile offshore platforms
- Jack-up rig legs, chords, and hulls
- Wind turbine foundations (monopiles, transition pieces)
- Semi-submersible rigs and floating production units
- Structural members where resistance to brittle fracture at low ambient temperatures is critical
Product Applications: Jack-up rig components, Monopile foundations, Transition pieces, Deck structures, Subsea templates, Bracing members
Processed into products: Platform legs, Hull plates, Stiffeners, Padeyes, Launch cradles, Mooring components, Welded tubular joints
Application industries: Oil & Gas Offshore, Renewable Energy (Offshore Wind), Marine & Shipbuilding, Heavy Civil Construction
EN10225 Grade S355G3+N Offshore Steel Plate Similar & Alternative Material Grades
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| Europe | EN 10025-3 | S355N/NL | Normalized structural steel; NL has -50 °C impact toughness |
| Europe | EN 10025-4 | S355M/ML | Thermomechanically rolled; similar strength, good weldability |
| Europe | EN 10225 | S355G10+N | Higher toughness grade within the same offshore standard |
| USA | ASTM A572/A572M | Grade 50 [345] | Similar yield strength, but not specifically for offshore service |
| International | DNVGL | NV A36 / NV D36 | Class society grades for ship and offshore structures |
Notes:
Special requirements: For thickness above 40 mm, supplementary ultrasonic testing (UT) per EN 10160 class S2/E2 is commonly specified. The +N delivery condition ensures impact properties at -40 °C. Welding must follow qualified procedures (low hydrogen, controlled heat input) to maintain toughness in the heat-affected zone. When service temperatures or design codes demand enhanced through-thickness strength, Z-quality plates (Z15, Z25, Z35 per EN 10164) can be ordered to mitigate lamellar tearing.
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