SA 203 GR.D Alloy Pressure Vessel Steel plate

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.

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Product Introduction

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

  1. ‌Cryogenic Toughness‌: 50J impact energy at -73°C (EN ISO 148-1)
  2. ‌Weld Efficiency‌: Preheat ≤50°C with AWS A5.23 EM12K filler metal
  3. ‌Corrosion Resistance‌: 0.015 mm/year corrosion rate in marine environments
  4. ‌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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Luo Kaiwei Steel Company is a comprehensive steel supplier that produces a variety of carbon steel plates, carbon steel pipes, galvanized steel, carbon steel coils, and steel profiles.

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