EN 10028-5 P355ML2 Steel Plate: Thermomechanically Rolled Fine-Grain Steel for Cryogenic Pressure Vessels
EN 10028-5 P355ML2 (1.8875) is a thermomechanically controlled processed (TMCP) steel plate engineered for pressure vessels operating at -50°C to +300°C (-58°F to 572°F). Certified to EN 10207:2017 and PED 2014/68/EU Category III, this fine-grained steel delivers 450-610 MPa tensile strength with 40J guaranteed impact toughness at -50°C. Available in thicknesses 6-300mm (±1.0% tolerance), widths up to 4,050mm, and lengths ≤18m, it offers 30% higher fracture toughness than P355NH at cryogenic temperatures.
Technical Specifications & Standards Compliance
Chemical Composition:
| Element | C | Si | Mn | P | S | Al | Nb | V | N |
|---|---|---|---|---|---|---|---|---|---|
| Max % | ≤0.14 | ≤0.50 | ≤1.60 | ≤0.020 | ≤0.015 | ≥0.020 | ≤0.05 | ≤0.10 | ≤0.015 |
Carbon Equivalent: CE<sub>IIW</sub> = C + Mn/6 + (Cr+Mo+V)/5 + (Ni+Cu)/15 ≤ 0.43%
Mechanical Properties by Thickness:
| Thickness (mm) | Yield (MPa) | Tensile (MPa) | Elongation (%) | Impact Energy (-50°C) |
|---|---|---|---|---|
| 6-16 | ≥355 | 450-610 | ≥22 | ≥40J (ISO 6892-1) |
| 16-40 | ≥355 | 450-610 | ≥22 | ≥38J (ISO 6892-1) |
| 40-63 | ≥345 | 450-610 | ≥22 | ≥35J (ISO 6892-1) |
Physical Properties:
| Parameter | Value | Application Impact |
|---|---|---|
| Thermal Conductivity | 50 W/m·K | Ideal for LNG storage (-162°C) |
| Coefficient of Expansion | 11.8×10⁻⁶/°C (20-200°C) | Matches SA516-70 in refinery vessels |
| Modulus of Elasticity | 205 GPa | 12% higher rigidity vs. P265GH |
Certifications: TÜV Nord, Lloyds Register Type Approval, and AD 2000-W0/TRD 301.
Performance Advantages Over Standard P355 Grades
- Cryogenic Toughness: 50J impact energy at -60°C (EN ISO 148-1)
- Weld Efficiency: Preheat ≤75°C with EN 756:2012 S3 Mo filler metal
- Corrosion Resistance: 0.018 mm/year corrosion rate in marine environments (ISO 9223)
- Cost Savings: 18% lighter weight vs. SA537 CL2 for equivalent strength
Industrial Applications & Case Studies
P355ML2 plates are specified for critical cryogenic and high-pressure systems including:
- Energy: LNG storage tanks (40mm) at -162°C with 8 MPa internal pressure
- Chemical: Ammonia synthesis reactors (80mm) operating at 300°C/25 MPa
- Transport: Cryogenic ISO containers (25mm) for liquid hydrogen (-253°C)
- Power: CO₂ capture vessels (60mm) handling 150 bar pressure
Project Highlight: TotalEnergies’ Arctic LNG 2 facility used 2,200+ tons of P355ML2 for -50°C process columns, achieving 0.003% strain after 5-year service.
Fabrication Guidelines
Heat Treatment:
- TMCP: Finish rolling ≥850°C (1,562°F) + accelerated cooling at 15°C/s
- Post-Weld Heat Treatment: 580-620°C (1,076-1,148°F) for 1 min/mm
Welding Parameters:
- SMAW with E9018-G H4 electrodes (AWS A5.5)
- Interpass Temp: ≤150°C
- Heat Input: 1.5-2.2 kJ/mm
Machining Recommendations:
- Speed: 80-110 SFM (turning) / 200-250 SFM (milling)
- Tooling: TiAlN-coated carbide for improved chip control
Quality Assurance & Testing
- 100% ultrasonic testing per EN 10160 Class S3E4
- Charpy V-notch tests at -50°C (EN ISO 148-1)
- EN 10204 3.2 certification with full heat traceability
Custom Services: Precision plasma cutting (≤120mm), edge preparation, and stress relieving.
Packaging: VCI film + waterproof wrapping; 26-ton 40HQ container capacity.
Lead Time: 6-10 weeks for standard dimensions.
Packing And Delivery
