ASME SA203 Gr.D Steel Plate: Nickel-Enhanced Alloy for Cryogenic Pressure Vessels & LNG Storage
SA203 Grade D (UNS K31545) is a quenched & tempered 2.25% nickel alloy steel plate designed for extreme low-temperature applications down to -196°C (-320°F). Certified to ASME SA203/ASTM A203M and PED 2014/68/EU, this normalized steel delivers 450-585 MPa tensile strength with 27J guaranteed impact toughness at -101°C. Available in thicknesses 6-150mm (±1.2% tolerance), widths up to 4,050mm, and lengths ≤15m, it offers 40% better fracture resistance than SA516-70 in LNG storage applications.
Technical Specifications & Material Advantages
Chemical Composition:
| Element | C | Mn | Si | Ni | P | S |
|---|---|---|---|---|---|---|
| Range | ≤0.17 | 0.70-0.80 | 0.13-0.45 | 2.25-2.75 | ≤0.035 | ≤0.035 |
Key Mechanical Properties:
| Thickness (mm) | Tensile (MPa) | Yield (MPa) | Elongation (%) | Impact (-101°C) |
|---|---|---|---|---|
| ≤16 | 450-585 | ≥255 | ≥23 | ≥34J (ASTM A370) |
| 17-40 | 450-585 | ≥255 | ≥21 | ≥30J (ASTM A370) |
| 41-150 | 450-585 | ≥255 | ≥19 | ≥27J (ASTM A370) |
Physical Properties:
| Parameter | Value | Application Impact |
|---|---|---|
| Thermal Conductivity | 38 W/m·K | Ideal for LNG tanks (-162°C) |
| Coefficient of Expansion | 10.9×10⁻⁶/°C (20-200°C) | Matches SA203 Gr.E in cryogenic pipes |
| Modulus of Elasticity | 198 GPa | 18% higher rigidity vs. SA516-65N |
Certifications: ABS Type Approval, NACE MR0175 (H₂S service), and EN 10204 3.1.
Performance Benefits Over Standard Grades
- Cryogenic Toughness: 50J impact energy at -73°C (EN ISO 148-1)
- Weld Efficiency: Preheat ≤50°C with AWS A5.23 EM12K filler metal
- Corrosion Resistance: 0.015 mm/year corrosion rate in marine environments
- Cost Savings: 25% lighter vs. SA537 CL1 for equivalent strength
Industrial Applications & Project Case Studies
SA203 Gr.D is widely used in critical low-temperature systems including:
- Energy: LNG storage tanks (125mm) operating at -162°C/15 bar
- Chemical: Ethylene fractionation towers (100mm) with 10,000+ thermal cycles
- Transport: Cryogenic railcar tanks (80mm) for liquid nitrogen (-196°C)
- Pharma: Liquid oxygen vessels (50mm) meeting ASME BPV Code Section VIII
Project Highlight: Shell’s Prelude FLNG facility utilized 3,500+ tons of SA203 Gr.D for -170°C liquefaction modules, achieving <0.002% strain after 3-year operation.
Fabrication & Processing Guidelines
Heat Treatment:
- Normalizing: 870-900°C (1,598-1,652°F) + air cooling
- Stress Relieving: 595-635°C (1,103-1,175°F) for 1.8 mins/mm
Welding Parameters:
- SAW with F11P8-EH12K flux/wire combo
- Interpass Temp: ≤150°C
- Heat Input: 1.4-2.0 kJ/mm
Machining Tips:
- Speed: 65-85 SFM (turning) / 170-210 SFM (milling)
- Tooling: PVD-coated carbide for chip control
Quality Assurance Protocols
- Full ultrasonic testing per ASTM A578 Level II
- Charpy V-notch tests at -101°C (ASTM E23)
- Batch-specific PMI verification via XRF
Custom Services: Waterjet cutting (≤300mm), edge preparation, and NDE testing.
Packaging: VCI film + desiccant packs; 20-ton 40HQ container capacity.
Certifications: Lloyds Register, DNV GL, and TÜV Nord approved.
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