UNS S31500|1.4417|3RE60 Seamless Duplex Steel Tube
Our S31500 duplex tubes are specifically designed to provide a strategic combination of high mechanical strength and exceptional resistance to chloride-induced stress corrosion cracking (SCC). With a yield strength nearly double that of conventional 300-series stainless steels, these tubes allow for thinner wall designs and increased pressure ratings in heat exchangers and chemical processing systems. Through advanced cold-drawing and precise solution annealing at our modern facilities, XinZhe ensures every tube maintains optimal phase balance and a high-integrity surface finish for the most demanding industrial environments.
"Our S31500 tubes offer a PREN value that ensures long-term durability in brackish water and mildly corrosive chemical media."
What Is a Seamless Duplex Steel S31500 Tube?
UNS S31500 is a lean duplex stainless steel with a balanced austenite-ferrite structure and lower nickel content than 2205. It offers high mechanical strength together with good resistance to chloride stress-corrosion cracking at a more economical alloy level, making it suitable for process piping, storage and water-handling duty where 2205 is not strictly required.
UNS S31500, commonly known as 3RE60 duplex stainless steel, is a first-generation duplex alloy featuring a balanced ferritic-austenitic microstructure (~50/50 phase structure).
This dual-phase composition provides an optimal combination of:
ASTM A789 S31500 seamless tubes are manufactured from solid billets via cold drawing or hot piercing, ensuring:
These properties make S31500 an ideal material for heat exchangers, chemical processing, and offshore systems.
Key Features and Technical Advantages
UNS S31500 Duplex Steel 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 Stress Corrosion Cracking (SCC) Resistance
- Ferritic phase provides strong resistance to chloride SCC
- Outperforms standard austenitic grades (304L / 316L) in aggressive environments
2. High Mechanical Strength
- Yield strength is approximately 2× higher than 300-series stainless steel
- Enables reduced wall thickness and material cost savings
3. Excellent Pitting & Crevice Corrosion Resistance
- Brackish water
- Sour gas environments
- Chloride-containing media
4. Improved Thermal Properties
- Higher thermal conductivity than austenitic steels
- Lower coefficient of thermal expansion
- Enhanced heat transfer efficiency in exchanger systems
5. Seamless Structural Reliability
- No longitudinal weld seams
- Eliminates risk of HAZ-related corrosion
- Optimized for high-pressure and critical service
Technical Specifications
- Stable duplex phase control (50/50 microstructure)
- High corrosion resistance at competitive cost
- Full certification and traceability
- Fast delivery for global industrial projects
Product Specifications and Data
- ASTM A789 / ASME SA789
- ASTM A1016 (General Requirements)
- EN 10216-5 (optional equivalent grades)
- JIS / GB standards available upon request
To provide a comprehensive overview of this high-performance material, here are the detailed technical specifications and performance data for UNS S31500 Duplex Steel.
The composition of UNS S31500 is carefully balanced to achieve its beneficial properties.
| 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 |
|---|---|---|---|
| ≥ 630 MPa | ≥ 440 MPa | ≥ 30% | ≤ 290 HBW |
| Density | Melting Point | Thermal Expansion | Thermal Conductivity | Modulus of Elasticity | Electrical Resistivity |
|---|---|---|---|---|---|
| 7.7 g/cm³ | 1450 - 1510 °C approx. | 13.0 µm/m·°C (20-100°C) | 18.0 W/m·K (20°C) | 200 GPa | 0.85 x 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
S31500 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
Oil and Gas Industry
- Process and utility piping
- Storage and transfer lines
- Moderately sour service
Chemical Processing
- Reactors and heat exchangers
- Chloride-bearing process streams
- Storage vessels
Desalination and Water Treatment
- Water transport piping
- Brine handling lines
- Treatment plant equipment
Pulp and Paper Industry
- Digester and liquor lines
- Bleach plant piping
- Heat-transfer equipment
Quality Assurance and Manufacturing Process
Certification
All Duplex S31500 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.
S31500 vs S32205 (2205) – Technical Comparison
S31500 is a lean duplex and S32205 is the standard duplex grade. The difference is mainly alloy content, and therefore cost against corrosion margin.
Chemical Composition
- S31500: lower nickel than 2205, with chromium and molybdenum at lean-duplex levels
- S32205: ~22% Cr, ~3% Mo, ~0.17% N — the reference duplex balance
- S31500 is the more economical of the two
Corrosion Resistance
S32205 offers higher resistance to pitting and crevice corrosion and a higher critical pitting temperature. S31500 retains good resistance to chloride stress-corrosion cracking, which is often the property that governs the design in process and water-handling duty.
Mechanical Strength
Both roughly double the yield strength of austenitic grades. S31500's lower alloy content keeps it more economical while preserving the strength advantage that motivates duplex selection in the first place.
Selection Guide
- Choose S31500 where chloride SCC resistance and high strength are required but the more aggressive chloride duty does not arise
- Choose S32205 where pitting and crevice resistance need the extra molybdenum and nitrogen
- Both are more economical than super duplex grades
Frequently Asked Questions
What is S31500 duplex tube?
UNS S31500 is a lean duplex stainless steel tube with a balanced austenite-ferrite structure and lower nickel content than 2205. It offers high mechanical strength and good chloride stress-corrosion resistance at a more economical alloy level.
What is the difference between S31500 and S32205?
S32205 (2205) contains more chromium, molybdenum and nitrogen, giving it higher pitting and crevice resistance and a higher critical pitting temperature. S31500 is the more economical grade, retaining good chloride SCC resistance and the duplex strength advantage.
What standard covers S31500 tube?
S31500 seamless tube is supplied to ASTM A789 / ASME SA789 and ASTM A790 / ASME SA790, with dimensional tolerances per ASTM A1016 / A1016M.
What is S31500 tube used for?
S31500 is used for oil and gas process and utility piping, chemical plant piping and vessels, water treatment and desalination lines, and pulp and paper process equipment.
Ready to Request a Quotation?
Send your Seamless Duplex Steel S31500 Tube enquiry with grade, application, size (OD and wall thickness or schedule), quantity, length, end finish and inspection requirements. Our technical team will confirm availability, testing scope and lead time.
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