UNS S32950|1.4655|S32950 Seamless Super Duplex Steel Tube
Designed for superior performance in chloride-rich media, our S32950 super duplex tubes provide exceptional resistance to pitting, crevice corrosion, and stress corrosion cracking (SCC). These tubes deliver a strategic combination of high tensile and yield strength alongside remarkable impact toughness, making them the optimal choice for high-pressure heat exchangers, desalination infrastructure, and offshore platforms. Through advanced cold-drawing and specialized solution annealing, XinZhe ensures every tube maintains optimal phase balance and a high-integrity surface finish for mission-critical reliability.
"Our S32950 tubes offer an optimized PREN value that ensures exceptional durability in brackish water and industrial chemical media."
What Is a Seamless Super Duplex S32950 Tube?
UNS S32950 is a super duplex stainless steel with a balanced austenite-ferrite structure and elevated chromium (26–29%) plus nitrogen. The high alloy content raises the PREN well above the duplex range, delivering markedly better resistance to pitting, crevice corrosion and chloride stress-corrosion cracking than standard 2205 duplex.
Seamless Super Duplex Steel UNS S32950 Tube is a high-performance stainless steel tubing solution manufactured from a solid billet without welding seams. This seamless construction ensures maximum structural integrity, leak resistance, and pressure reliability in demanding environments.
UNS S32950 is a Super Duplex Stainless Steel grade featuring a balanced austenite–ferrite (50:50) microstructure, combining:
With elevated chromium (26–29%) and nitrogen content, S32950 offers significantly improved performance compared to:
Key Features and Technical Advantages
S32950 is specifically designed to maintain its strength and shape in high-stress, corrosive environments.
These physical properties highlight the material's ability to perform reliably under a wide range of conditions.
1. Superior Corrosion Resistance
- High PREN value (≥ 40 typical)
- Pitting corrosion
- Crevice corrosion
- Chloride-rich environments
2. High Strength & Weight Reduction
- Yield strength ≈ 2× higher than 316L stainless steel
- Reduced wall thickness
- Lower system weight
- Cost-efficient engineering design
3. Excellent SCC Resistance
- Ferritic phase provides natural resistance to chloride-induced SCC
- Ensures long service life in aggressive environments
4. Thermal & Structural Stability
- In cryogenic conditions
- Under moderately high temperatures
Standards & Compliance
- ASTM A789 / ASME SA789
- ASTM A790 / ASME SA790
- ASTM A1016
- NACE MR0175 (if required for sour service)
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 S32950.
The composition of S32950 is carefully balanced to achieve its superior corrosion resistance and high strength.
| Grade | C | Mn | P | S | Si | Ni | Cr | Mo | N | Cu | Others |
| 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 | 4.3-5.2 | 18.00-19.00 | 2.50-3.00 | 0.05-0.10 | … | … |
| 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 | 1.50-2.50 | … |
| 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 | ≤0.03 | ≤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 | ≤0.03 | ≤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 | … |
| Tensile Strength | Yield Strength | Elongation | Hardness |
|---|---|---|---|
| ≥795 MPa | ≥550 MPa | ≥25% | ≤290 HBW |
| Density | Melting Point | Thermal Expansion | Thermal Conductivity | Modulus of Elasticity | Electrical Resistivity |
|---|---|---|---|---|---|
| 7.8 g/cm3 | 1400−1440 ∘C approx. | 13.0 μm/m⋅∘C (20−100∘C) | 15 W/m⋅K (20∘C) | 200 GPa | 0.80×10−6 Ω⋅m (20∘C) |
| 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 |
Dimensional Standards and Tolerances
S32950 super duplex seamless tubes are supplied to the dimensional tolerances of ASTM A789 / A1016 unless a tighter project specification applies.
- For Specific 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.
Common Industrial Applications
Offshore Oil and Gas
- Flowlines and manifolds
- Sour and high-chloride service
- High-pressure process tubing
Desalination and Water Treatment
- RO membrane high-pressure piping
- Brine and reject handling
- Evaporator tubing
Chemical and Petrochemical
- Heat exchangers and reactors
- Chloride-bearing process streams
- Acid service piping
Marine Engineering
- Seawater systems
- Propulsion and cooling pipework
- Port and harbour infrastructure
Quality Assurance and Manufacturing Process
Certification
All Super Duplex S32950 tubes are supplied to ASTM A789 / ASME SA789 and ASTM A790 / ASME SA790 with EN 10204 3.1 mill test certificates. Third-party inspection (SGS, BV, TUV, Lloyd's), PMI reports and full heat-number traceability can be provided on request.
Non-Destructive Testing (NDT)
Hydrostatic or eddy-current testing is performed on 100% of tubes. Ultrasonic testing (UT) and dye-penetrant inspection (PT) are available for critical service, with records retained for each production lot.
Material Verification
Positive Material Identification (PMI) and spectrometric analysis confirm that the chemical composition matches the ordered grade and that the ferrite/austenite balance is within the specified range.
Mechanical Testing
Tensile, yield, elongation and hardness tests are carried out per heat. Impact testing can be supplied at the project design temperature for subsea and low-temperature service.
Dimensional Inspection
Outside diameter, wall thickness, ovality and straightness are measured against ASTM A1016 / A1016M or ASTM A789 tolerances. Length, square-cut ends and end-finish conditions are verified before packing.
S32950 vs S32750 (2507) – Technical Comparison
S32950 and S32750 both sit in the super duplex family, but their chromium and molybdenum balances differ, which shifts where each performs best.
Chemical Composition
- S32950: 26–29% Cr, ~1.5% Mo, ~0.3% N — notably higher chromium, lower molybdenum
- S32750: ~25% Cr, ~4% Mo, ~0.3% N — lower chromium, higher molybdenum
- Both are balanced duplex with high PREN
Corrosion Resistance
S32950's higher chromium favours resistance in oxidising and nitric-acid-bearing environments, while S32750's higher molybdenum favours resistance to pitting and crevice attack in chloride-bearing media. Both resist chloride stress-corrosion cracking well.
Mechanical Strength
Both grades deliver roughly twice the yield strength of standard austenitic stainless steels, allowing thinner walls and lighter structures, with good toughness maintained to sub-zero temperatures.
Selection Guide
- Choose S32950 where oxidising acid resistance and high chromium content matter most
- Choose S32750 where maximum pitting and crevice resistance in chloride service is the priority
- Confirm the actual service chemistry before selecting between them
Frequently Asked Questions
What is S32950 super duplex tube?
UNS S32950 is a super duplex stainless steel tube with a balanced austenite-ferrite structure and elevated chromium (26–29%) plus nitrogen. The high alloy content raises the PREN well above the standard duplex range.
How does S32950 compare with S32750?
S32950 carries higher chromium and lower molybdenum than S32750. Its higher chromium favours resistance in oxidising and nitric-acid-bearing environments, while S32750's higher molybdenum favours pitting and crevice resistance in chloride-bearing media.
What is S32950 tube used for?
S32950 serves in offshore oil and gas flowlines and manifolds, desalination and water treatment piping, chemical and petrochemical process lines, and marine engineering where high strength and chloride resistance are both required.
What standard covers S32950 tube?
S32950 seamless tube is supplied to ASTM A789 / ASME SA789 and ASTM A790 / ASME SA790, with dimensional tolerances per ASTM A1016 / A1016M.
Ready to Request a Quotation?
Send your Seamless Super Duplex S32950 Tube enquiry with grade, application, size (OD and wall thickness or schedule), quantity, length, end finish and inspection requirements including any ferrite content limits or third-party witnessing.
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