Seamless Duplex Steel S31500 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, GZH 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?
Seamless Duplex Steel S31500 Tube is a high-performance, cylindrical tube crafted from a single, solid billet of a duplex stainless steel alloy. Unlike welded tubes, it has no weld joint, ensuring superior structural integrity and reliability, especially under high-stress and corrosive conditions. The"UNS S31500"designation refers to a specific grade of duplex stainless steel known for its good balance of corrosion resistance and high strength. This alloy has a unique two-phase microstructure of roughly equal parts austenite and ferrite, providing a beneficial combination of high tensile strength, good toughness, and resistance to stress corrosion cracking, making it a reliable choice for demanding applications.
Key Features and Advantages
Seamless Duplex Steel S31500 Tube offer a unique combination of benefits that make them valuable in demanding industries:
Exceptional Corrosion Resistance: It provides good resistance to pitting, crevice corrosion, and stress corrosion cracking in chloride-containing environments.
High Strength: The duplex (austenite-ferrite) microstructure provides a high tensile and yield strength, approximately double that of standard austenitic stainless steels like 304L.
Good Weldability: The alloy's lower alloy content compared to other duplex grades makes it easier to weld while maintaining its favorable properties.
High Pressure Tolerance: The seamless construction eliminates a potential weak point, allowing the tube to safely handle high internal pressures, which is critical in many fluid transfer and structural applications.
Cost-Effectiveness: It provides a good balance of performance and cost, making it a more economical choice than higher-alloyed duplex or super duplex steels for certain applications.
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.
Table 1: Chemical Composition of UNS S31500
The composition of UNS S31500 is carefully balanced to achieve its beneficial properties.
| 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 | … |
Table 2: Typical Mechanical Properties of UNS S31500 Duplex Steel
UNS S31500 Duplex Steel is specifically designed to maintain its strength and shape in high-stress, corrosive environments.
| Property | Value (Annealed) |
| Tensile Strength | ≥ 590 MPa |
| Yield Strength | ≥ 400 MPa |
| Elongation | ≥ 30% |
| Hardness | ≤ 290 HBW |
Table 3: Typical Physical Properties of UNS S31500 Duplex Steel
These physical properties highlight the material's ability to perform reliably under a wide range of conditions.
| Property | Value |
| Density | 7.7 g/cm³ |
| Melting Point | 1450 - 1510 °C approx. |
| Thermal Expansion | 13.0 µm/m·°C (20-100°C) |
| Thermal Conductivity | 18.0 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.
Common Applications
The combination of high strength and good corrosion resistance of Seamless Duplex Steel 315 Tube makes them a preferred choice for:
Chemical Processing: In heat exchangers, pressure vessels, and piping for moderately corrosive environments.
Oil and Gas Industry: Used in offshore platforms, piping systems, and heat exchangers where resistance to chloride and sour gas corrosion is needed.
Desalination Plants: For piping and vessels where components must handle moderate-chloride water.
Pulp and Paper Industry: In equipment where a combination of strength and corrosion resistance is required.
Manufacturing Process
The manufacturing of a Seamless Duplex Steel Tube is a precise, multi-step process:
- Heating: A solid billet of UNS S31500 is heated to a high temperature.
- Piercing: A piercing mill pushes a mandrel through the center of the heated billet to form a hollow shell.
- Rolling and Sizing: The hollow shell is then rolled and drawn to reduce its diameter and wall thickness to the desired dimensions.
- Finishing: The tube is cut to length, heat-treated, and subjected to finishing processes to ensure it meets the highest standards for performance and reliability. This meticulous process ensures that every UNS S31500 seamless tube meets the highest standards for performance and reliability in demanding applications.
