The Power and Promise of Super Duplex S32750 Tubes

The Power and Promise of Super Duplex S32750 Tubes

Super Duplex S32750 (also known as UNS S32750 or Alloy 2507) is a high-alloy duplex stainless steel featuring a balanced ferritic–austenitic microstructure. This unique composition delivers unmatched corrosion resistance, superior mechanical strength, and excellent weldability. The grade typically contains about 25% chromium, 7% nickel, 3–4% molybdenum, and a small but critical amount of nitrogen (~0.24–0.32%)

Outstanding Material Properties

• Corrosion Resistance: Exceptional performance in chloride-rich and harsh environments. It resists pitting, crevice corrosion, and stress corrosion cracking far better than standard stainless steels, boasting a PREN (Pitting Resistance Equivalent Number) of ~42 +

• Mechanical Strength: S32750 offers tensile strength ranging from 800 to 1000 MPa and a minimum yield strength around 550 MPa, nearly double that of traditional austenitic stainless types

• Heat Resistance: Excellent performance at elevated temperatures with strong thermal stability. Lower thermal expansion and higher heat conductivity further enhance performance in demanding conditions

• Weldability & Fabrication: Despite high alloy content, it remains reasonably weldable with standard procedures. The rapid heat treatment and balanced microstructure help maintain integrity—but hot working requires quicker cooling to avoid brittle sigma phase formation

  Typical Applications of S32750 Tubes

  Due to its performance and durability, S32750 tubing finds use across many industries:

  • Oil & Gas: Offshore platforms, subsea pipelines, pressure vessels, heat exchangers, and structural components Marine & Desalination: Systems exposed to warm, chlorinated seawater, including desalination plants and sea-water cooling circuits

  • Chemical & Petrochemical: Reaction vessels, storage tanks, piping systems, and flue-gas scrubbers Pulp & Paper: Equipment handling bleaching, digesters, and corrosive process environments

  • Pollution Control: Flue-gas desulfurization units, wastewater treatment equipment, and other severe service systems 

  Specifications & Manufacturing Formats

  S32750 outperforms across a variety of product forms:

  • Standards: Manufactured per ASTM A789/A790 (ASME SA789/SA790) 

  • Forms & End Conditions: Comes as seamless, ERW, welded, or fabricated tubes/pipes in round, square, rectangular, coiled, or U-shaped forms. End finishes include plain, beveled, or threaded 

  • Sizes:

    • OD range: 6 mm to 630 mm

    • Wall thickness: 0.5 mm to 45 mm (or higher, per supplier) 

  • Schedules: Standard schedules (SCH 10–160, XS, XXS, etc.) are available, alongside custom lengths up to ~25 meters

  • Finishes & Services: Bright annealed, polished (No.1, No.4, #8 mirror), cutting, threading, beveling, testing (PMI, flattening/flaring, ultrasonic, radiography), and documentation like MTC per EN 10204/3.1B 

  Benefits vs. Limitations

  Advantages	Limitations
  Exceptional corrosion resistance, high strength, thermal stability	Higher cost than conventional stainless steels
  Allows thinner sections for equivalent strength—material savings	Requires strict thermal control in fabrication
  Long service life with lower maintenance needs	More specialized welding/fabrication expertise required

  Conclusion: A Smart Investment for Tough Jobs

  Super Duplex S32750 tubing delivers unmatched performance in environments that challenge other materials—whether exposed to aggressive chemicals, high chloride content, or thermal extremes. Its superiority in corrosion resistance and mechanical properties, coupled with long-term durability, makes it a value-driven solution despite its initially higher price tag