Seamless Duplex Stainless Steel S31500 Tube-ASTM A789 UNS S31500 (3RE60) | High-Strength & Corrosion-Resistant Duplex Tubing
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:
- High mechanical strength
- Excellent resistance to chloride-induced stress corrosion cracking (SCC)
- Improved thermal conductivity
ASTM A789 S31500 seamless tubes are manufactured from solid billets via cold drawing or hot piercing, ensuring:
- No weld seam defects
- Superior pressure-bearing capacity
- Uniform metallurgical structure
These properties make S31500 an ideal material for heat exchangers, chemical processing, and offshore systems.
Key Features and Performance Advantages
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
- Suitable for:
- 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
Applicable Standards
- ASTM A789 / ASME SA789
- ASTM A1016 (General Requirements)
- EN 10216-5 (optional equivalent grades)
- JIS / GB standards available upon request
Product Specifications and Data
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.
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.
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.
Common Industrial Applications
- Downhole tubing
- Flowlines
- Heat exchangers in sour gas servic
Oil & Gas Industry
- Downhole tubing
- Flowlines
- Heat exchangers in sour gas service
Chemical Processing
- Organic acid production systems
- Chloride-containing process pipelines
Desalination & Water Treatment
- Evaporators
- Brackish water piping systems
Pulp & Paper Industry
- Digesters
- Bleaching systems
- Equipment requiring high fatigue resistance
Manufacturing Process & Quality Assurance
Each S31500 seamless tube undergoes strict process control and inspection:
Manufacturing Process
- Hot Piercing & Cold Drawing
- Solution Annealing at 1020°C–1100°C
- Rapid quenching to maintain 50/50 duplex phase balance
Inspection & Testing
Non-Destructive Testing (NDT)
- 100% Eddy Current Testing (ET)
- Ultrasonic Testing (UT)
Mechanical Testing
- Tensile Testing
- Flattening and Flaring Tests
- Hardness Testing
Corrosion Testing
- ASTM A262 Practice E
- Optional SCC (Stress Corrosion Cracking) testing
Why Choose Our S31500 Seamless Tubes?
- Stable duplex phase control (50/50 microstructure)
- High corrosion resistance at competitive cost
- Full certification and traceability
- Fast delivery for global industrial projects
