1. Key Parameters

• Chemical Composition (Typical, %):
  • Chromium (Cr): 24.0–26.0
  • Nickel (Ni): 5.5–7.5
  • Molybdenum (Mo): 2.5–3.5
  • Carbon (C): ≤0.03
  • Nitrogen (N): 0.14–0.20
  • Iron (Fe): Balance
    These elements contribute to the alloy’s duplex microstructure (a mix of austenite and ferrite), enhancing its corrosion resistance and strength.
• Mechanical Properties:
  • Tensile Strength: ≥690 MPa (≥100 ksi)
  • Yield Strength (0.2% offset): ≥450 MPa (≥65 ksi)
  • Elongation: ≥25% (in 50 mm)
  • Hardness: ≤29 HRC

2. Applicable Standards

• Chemical composition
• Mechanical properties (tensile strength, yield strength, elongation)
• Dimensional tolerances
• Non-destructive testing (e.g., ultrasonic testing, hydrostatic testing)
• Surface finish

3. Specifications

• Dimensions:
  • Outer Diameter (OD): Typically from 6 mm (0.25 inches) to 610 mm (24 inches), with custom sizes available.
  • Wall Thickness (WT): From 0.5 mm (0.02 inches) to 50 mm (2 inches), depending on OD and application requirements.
  • Length: Standard lengths include 6 meters (20 feet) or 12 meters (40 feet); cut-to-length options are also offered.
• Surface Finish:
  • Annealed and pickled (AP): For general applications, providing a clean, corrosion-resistant surface.
  • Polished: Optional (e.g., 2B, BA finishes) for applications requiring enhanced hygiene or aesthetics.
• End Connections:
  • Plain ends (PE)
  • Beveled ends (for welding)
  • Threaded ends (per ASTM A530 or customer specifications)

4.Equivalent Grades of UNS S31200 Stainless Steel

• European Standard (EN): 1.4462
• ISO: X2CrNiMoN25-7-4
• Japanese Industrial Standard (JIS): SUS 329J4L
• Chinese Standard (GB): 022Cr25Ni7Mo4N

5. Characteristics

• Excellent Corrosion Resistance:
  • Resistant to pitting and crevice corrosion in chloride-rich environments (e.g., seawater, brines) due to high chromium, molybdenum, and nitrogen content.
  • Good resistance to general corrosion, stress corrosion cracking (SCC), and erosion-corrosion.
• High Mechanical Strength:
  • Duplex microstructure provides higher strength than austenitic stainless steels (e.g., 304, 316), reducing wall thickness requirements and overall weight.
• Good Weldability:
  • Can be welded using common methods (TIG, MIG, SMAW) with proper control of heat input to maintain duplex balance.
• Cost-Effectiveness:
  • Offers a favorable strength-to-cost ratio compared to high-nickel austenitic or super duplex grades.

6. Applications

• Marine Engineering: Seawater intake systems, desalination plants, offshore oil and gas platforms.
• Chemical Processing: Piping for handling acids, alkalis, and corrosive chemicals.
• Oil and Gas Industry: Downhole tubing, flowlines, and offshore pipeline components.
• Water Treatment: Piping in wastewater treatment plants and industrial water systems.
• Power Generation: Cooling water systems in thermal and nuclear power plants.