Stainless Steel Duplex Pipe
High-Strength Dual-Phase (Austenitic-Ferritic) Stainless Steel Pipes
Duplex Stainless Steel Pipe (UNS S31803 / S32205) is a nitrogen-enhanced stainless steel designed to provide the combined benefits of the 300 series (austenitic) and 400 series (ferritic) steels. With a microstructure consisting of approximately 50% austenite and 50% ferrite, it offers nearly double the yield strength of standard austenitic grades. It is highly resistant to stress corrosion cracking (SCC), pitting, and crevice corrosion, making it the premier choice for demanding offshore and chemical environments.
Technical Specifications
| Feature | Details |
|---|---|
| Standards | ASTM A790, ASME SA790, ASTM A928 (Welded) |
| Grade | Duplex 2205 (UNS S31803 / S32205) |
| Outer Diameter | 1/8" NB to 24" NB (Seamless), Up to 48" (Welded) |
| Wall Thickness | SCH 5S, 10S, 40S, 80S, SCH 160, XXS |
| Type | Seamless / Welded / ERW / LSAW / Fabricated |
| Value Added Services | Beveling, Threading, Polishing, Solution Annealing |
Mechanical Properties
| Property | Standard Value (Annealed) | Industrial Performance |
|---|---|---|
| Yield Strength (0.2% Offset) | Min 450 MPa | High Load Bearing Capacity |
| Tensile Strength (Min) | 620 MPa | Superior Structural Integrity |
| Elongation (Min %) | 25% | Excellent Ductility |
| Hardness (Brinell) | Max 293 HBW | High Wear Resistance |
Chemical Composition (%)
| Element | Duplex 2205 Percentage |
|---|---|
| Carbon (C) | 0.030 max |
| Manganese (Mn) | 2.00 max |
| Chromium (Cr) | 21.0 - 23.0 |
| Nickel (Ni) | 4.5 - 6.5 |
| Molybdenum (Mo) | 2.5 - 3.5 |
| Nitrogen (N) | 0.08 - 0.20 |
| Phosphorus (P) | 0.030 max |
| Sulphur (S) | 0.020 max |
| Iron (Fe) | Balance |
Features and Benefits of Duplex Pipe
- Dual-Phase Microstructure: Combines the strength of ferritic steel with the ductility of austenitic steel.
- Stress Corrosion Resistance: Exceptional resistance to chloride-induced stress corrosion cracking.
- Cost-Efficiency: Higher strength allows for thinner wall thickness, reducing overall material weight and cost.
- Pitting Resistance: High Chromium and Molybdenum content provides superior pitting and crevice corrosion resistance.
- Low Thermal Expansion: Better suited for heat exchangers than standard austenitic grades.
- High Weldability: Good weldability when using appropriate filler metals and cooling rates.
Applications & Uses
Marine & Offshore
Widely used in seawater cooling systems, desalination plants, and subsea pipelines.
Chemical Processing
Ideal for pressure vessels, tanks, and piping systems handling corrosive acidic media.
Oil & Gas
Critical for sour gas processing, scrubbers, and downhole production tubing.