Seamless Super Duplex Steel S32760 Tube
Featuring an exceptionally high Pitting Resistance Equivalent Number (PREN ≥ 41), our S32760 tubes provide superior resistance to pitting and crevice corrosion in aggressive chloride environments. The addition of tungsten and copper enhances its stability in both organic and inorganic acids, making it a superior choice for sour gas (H2S) services, desalination, and subsea infrastructure. Through advanced cold-drawing and precise solution annealing, GZH ensures every tube maintains optimal phase balance and unmatched mechanical strength, even in the most demanding offshore applications.
PREN =%Cr + 3.3X(%Mo + 0.5X%W) + 16X%N≥ 41
Seamless Super Duplex Steel S32760 Tube
High-Performance Tubing for Extreme Corrosion and High-Pressure Environments
What is a Seamless Super Duplex S32760 Tube?
ASeamless Super Duplex Steel S32760 tube is a high-alloy stainless steel tube specifically engineered for extremely aggressive industrial environments. These tubes are produced through hot piercing and cold drawing processes from a solid billet, creating a fully homogeneous metallurgical structure without weld seams.
Compared with welded pipes, seamless S32760 tubing eliminates the risk of weld-line corrosion and heat-affected zones, providing superior structural reliability in critical applications.
The alloy is commonly designated as UNS S32760, also known as F55, a premium grade within the Super Duplex Stainless Steelfamily.
Super duplex steels are characterized by a balanced 50/50 austenitic–ferritic microstructure, combining the corrosion resistance of austenitic stainless steels with the mechanical strength of ferritic grades.
The chemical composition of S32760 includes elevated levels of:
- Chromium (Cr)
- Molybdenum (Mo)
- Nitrogen (N)
and additional alloying elements such as:
- Copper (Cu)
- Tungsten (W)
This optimized chemistry results in a Pitting Resistance Equivalent Number (PREN) greater than 40, placing S32760 among the most corrosion-resistant stainless steels available for industrial use.
Technical Advantages of Seamless S32760 Tubing
Outstanding Pitting and Crevice Corrosion Resistance
Super Duplex S32760 tubing provides exceptional resistance to localized corrosion mechanisms such as pitting and crevice corrosion. It performs reliably in high-chloride environments and sour gas conditions where conventional grades like 316L stainless steel or even Duplex 2205 stainless steel may fail.
High Mechanical Strength
S32760 offers approximately twice the yield strength of standard austenitic stainless steels, allowing engineers to design thinner wall structures while maintaining high pressure capability. This property significantly reduces structural weight in offshore and subsea installations.
Excellent Stress Corrosion Cracking Resistance
The ferritic phase of the duplex microstructure provides strong resistance to chloride-induced stress corrosion cracking (SCC), making the alloy particularly suitable for seawater and desalination systems.
Enhanced Fatigue and Pressure Performance
The seamless manufacturing process eliminates heat-affected zones, ensuring uniform burst strength and improved fatigue resistance under cyclic pressure conditions.
Reliable Low-Temperature Toughness
S32760 maintains excellent impact toughness even at sub-zero temperatures, allowing it to perform reliably in Arctic offshore projects and cryogenic service environments.
Product Specifications and Data
To provide a comprehensive overview of this high-performance material, here are the detailed technical specifications and performance data for Super Duplex Steel UNS S32760.
Table 1: Chemical Composition of UNS S32760
The composition of UNS S32760 is carefully balanced to achieve its superior corrosion resistance and high strength.
| Grade | C | Mn | P | S | Si | Ni | Cr | Mo | N | Cu | Ohters |
| 31803 | ≤0.03 | ≤2.00 | ≤0.03 | ≤0.02 | ≤1.00 | 4.50-6.50 | 21.00-23.00 | 2.50-3.50 | 0.08-0.20 | … | … |
| 32205 | ≤0.03 | ≤2.00 | ≤0.03 | ≤0.02 | ≤1.00 | 4.50-6.50 | 22.00-23.00 | 3.00-3.50 | 0.14-0.20 | … | … |
| 31500 | ≤0.03 | 1.20-2.00 | ≤0.03 | ≤0.03 | 1.40-2.00 | 4.20-5.20 | 18.00-19.00 | 2.50-3.00 | 0.15-0.10 | 1.50-2.50 | … |
| 32550 | ≤0.04 | ≤1.50 | ≤0.04 | ≤0.03 | ≤1.00 | 4.50-6.50 | 24.00-27.00 | 2.90-3.90 | 0.10-0.25 | … | … |
| 32750 | ≤0.03 | ≤1.20 | ≤0.035 | ≤0.02 | ≤0.80 | 6.00-8.00 | 24.00-26.00 | 3.00-5.00 | 0.24-0.32 | ≤0.50 | … |
| 32760 | ≤0.05 | ≤1.00 | ≤0.030 | ≤0.01 | ≤1.00 | 6.00-8.00 | 24.00-26.00 | 3.00-4.00 | 0.20-0.30 | 0.50-1.00 | W 0.50 -1.00 |
| 32950 | ≤0.08 | ≤2.00 | ≤0.035 | ≤0.01 | ≤0.60 | 3.50-5.20 | 26.00-29.00 | 1.00-2.50 | 0.15-0.35 | … | … |
| 32906 | ≤0.03 | 0.80-1.50 | ≤0.030 | ≤0.03 | ≤0.50 | 5.80-7.50 | 28.00-30.00 | 1.50-2.60 | 0.30-0.40 | ≤0.80 | … |
NOTE: PREN:Cr+3.3*(Mo+0.5*W)+16*N≥41 |
Table 2: Typical Mechanical Properties of UNS S32760
UNS S32760 is specifically designed to maintain its strength and shape in high-stress, corrosive environments.
| Property | Value |
| Tensile Strength | ≥750 MPa |
| Yield Strength | ≥550 MPa |
| Elongation | ≥25% |
| Hardness | ≤270 HBW |
Table 3: Typical Physical Properties of UNS S32760
These physical properties highlight the material's ability to perform reliably under a wide range of conditions.
| Property | Value |
| Density | 7.8 g/cm³ |
| Melting Point | 1450 °C approx. |
| Thermal Expansion | 13.5 µm/m·°C (20-100°C) |
| Thermal Conductivity | 15.0 W/m·K (20°C) |
| Modulus of Elasticity | 200 GPa |
| Electrical Resistivity | 0.85 x 10⁻⁶ Ω·m (20°C) |
Table 4: The Standard of ASTM A789 Size Tolerance Size Chart :
| Specified Outside Diameter (OD) (Inches) | Permissible Variations in OD (± Inches) |
| 1⁄2 to 1 | ±0.005 |
| Over 1 to 1-1⁄2 | ±0.008 |
| Over 1-1⁄2 to 2 | ±0.010 |
| Over 2 to 2-1⁄2 | ±0.012 |
| Over 2-1⁄2 to 3-1⁄2 | ±0.014 |
| Over 3-1⁄2 to 5 | ±0.020 |
| Specified Outside Diameter (OD) (Inches) | Specified Wall Thickness (WT) (Inches) | Permissible Variation (± Inches) |
| 1⁄2 to 1 (Inclusive) | 0.025 to 0.065(Inclusive) | ±0.010 |
| Over 0.065to 0.134 (Inclusive) | ±0.012 | |
| Over 1 to 1-1⁄2 (Inclusive) | 0.025 to 0.065 (Inclusive) | ±0.010 |
| Over 0.065 to 0.134 (Inclusive) | ±0.012 | |
| Over 1-1⁄2 to 2 (Inclusive) | 0.025 to 0.049 (Inclusive) | ±0.011 |
| Over 0.049 to 0.083 (Inclusive) | ±0.012 | |
| Over 0.083 to 0.148 (Inclusive) | ±0.014 | |
| Over 2 to 2-1⁄2 (Inclusive) | 0.032 to 0.065 (Inclusive) | ±0.013 |
| Over 0.065 to 0.109 (Inclusive) | ±0.015 | |
| Over 0.109 to 0.165 (Inclusive) | ±0.017 | |
| Over 2-1⁄2 to 3-1⁄2 (Inclusive) | 0.032 to 0.165 (Inclusive) | ±0.020 |
| Over 0.165 to 0.220 (Inclusive) | ±0.025 | |
| Over 3-1⁄2 to 5 (Inclusive) | 0.083 to 0.165 (Inclusive) | ±0.025 |
| Over 0.165 to 0.220 (Inclusive) | ±0.030 |
Length Tolerance
ForSpecific Cut Lengths, the standard tolerance is +1⁄8 in. [3 mm], -0 in. [0 mm].
Important Note: The values presented here are based on the common tables in the ASTM A789 standard. The full specification, particularly the referenced ASTM A1016/A1016M (General Requirements for Ferritic Alloy Steel, Austenitic Alloy Steel, and Stainless Steel Tubes), contains other essential requirements like straightness and details for tubes with ODs outside of this range. Always consult the latest official standard for design and procurement.
Typical Applications of Super Duplex S32760 Seamless Tubes
Due to its exceptional corrosion resistance and mechanical strength, S32760 seamless tubing is widely used in highly demanding industries.
Oil and Gas Production
Subsea manifolds, flowlines, and umbilicals operating under high pressure and exposed to H₂S and CO₂environments.
Desalination and Water Treatment
High-pressure reverse osmosis systems and brine circulation piping in seawater desalination plants.
Chemical and Petrochemical Processing
Heat exchangers, reactors, and pipelines handling aggressive acids, chloride solutions, and catalytic chemicals.
Marine and Offshore Engineering
Propeller shafts, rudder systems, offshore structural components, and seawater handling equipment.
Quality Assurance and Inspection Standards
To meet strict international engineering standards such as NORSOK M650,ASTM A789, and ASTM A790, every Seamless Super Duplex S32760 tube undergoes comprehensive quality control procedures.
Material Certification
- EN 10204 3.1 and 3.2 Material Test Certificates (MTC)
Non-Destructive Testing (NDT)
- 100% Ultrasonic Testing (UT)
- Eddy Current Testing (ET)
- Hydrostatic Pressure Testing
Chemical Composition Verification
- Positive Material Identification (PMI)
- Full traceability of raw materials
Mechanical and Corrosion Testing
- Tensile and hardness testing
- Charpy V-Notch impact testing
- Intergranular corrosion testing (IGC)
Metallurgical Analysis
- Ferrite phase balance verification
- ASTM G48 pitting corrosion testing
Super Duplex S32760 vs Duplex 2205
Understanding the differences between Super Duplex S32760andDuplex 2205 helps engineers select the most suitable material for demanding applications.
Property | Duplex 2205 (S31803 / S32205) | Super Duplex S32760 (F55) |
Microstructure | Dual-phase Austenite/Ferrite | Enhanced Dual-phase with W and Cu |
PREN | 34 – 36 | ≥ 41 |
Yield Strength | Approx. 450 MPa | Approx. 550 MPa |
Chloride Resistance | Excellent in seawater | Superior in hot brine and sour gas |
Critical Pitting Temperature | ~35°C | >50°C |
Engineering Insight
The superior corrosion resistance of S32760 is achieved through a carefully balanced alloy design combining high chromium, molybdenum, and nitrogen levels with tungsten additions. This composition ensures a PREN ≥ 41, allowing the material to remain passive in extremely aggressive chloride environments where conventional duplex steels may experience localized corrosion.
Summary
Seamless Super Duplex S32760 tubes represent one of the most advanced stainless steel solutions for extreme industrial environments. By combining the superior corrosion resistance of super duplex alloys with the structural integrity of seamless manufacturing, S32760 tubing delivers exceptional performance in offshore oil and gas, desalination, petrochemical processing, and marine engineering applications.
Its high PREN value, outstanding mechanical strength, and excellent resistance to stress corrosion cracking make S32760 seamless tubing a preferred choice for critical high-pressure and high-corrosion service conditions.
