Corrosion resistant duplex steel pipe is specifically engineered for service in aggressive environments where standard stainless steels such as 304 and 316 are prone to failure. The unique two-phase microstructure (austenite + ferrite) combined with elevated levels of chromium, molybdenum, and nitrogen provides exceptional resistance to a wide range of corrosive attack mechanisms.
Our duplex steel pipes offer outstanding protection against pitting, crevice corrosion, stress corrosion cracking (SCC), general corrosion, and erosion-corrosion, making them the preferred choice for chemical, marine, oil and gas, and desalination applications.
Product Specifications
| Parameter |
Details |
| Standard |
ASTM A790, A789, A928, EN 10216-5, EN 10217-7, NACE MR0175 |
| Grades |
2205 (UNS S31803, S32205), 2507 (UNS S32750), 2304 (UNS S32304), S32760 |
| Size (OD) |
6.0 mm – 1829 mm (1/8" – 72") |
| Wall Thickness |
0.5 mm – 50.0 mm |
| Length |
3000 mm, 6000 mm, random lengths, custom cut |
| Process |
Seamless or Welded (ERW, EFW, DSAW) |
| Surface Finish |
Annealed and pickled, Bright annealed, Mechanically polished |
Corrosion Resistance Mechanisms
| Corrosion Type |
Duplex Steel Resistance |
Mechanism |
| Pitting |
Excellent to Superior |
High Cr, Mo, and N content (PREN 25-45+) |
| Crevice Corrosion |
Excellent to Superior |
Same alloying elements protect shielded areas |
| Stress Corrosion Cracking (SCC) |
Excellent |
Ferrite phase arrests crack propagation |
| General Corrosion |
Good to Excellent |
High Cr content forms stable passive film |
| Erosion-Corrosion |
Good |
High hardness and strength resist wear |
| Intergranular Corrosion |
Excellent |
Low carbon content prevents sensitization |
| Galvanic Corrosion |
Good |
Compatible with austenitic grades when coupled |
| Hydrogen Induced Cracking (HIC) |
Good (with NACE) |
Suitable for sour service with certification |
Chemical Composition by Grade (Reference %)
| Element |
2205 (S32205) |
2507 (S32750) |
2304 (S32304) |
S32760 |
| Carbon (C) ≤ |
0.030 |
0.030 |
0.030 |
0.030 |
| Chromium (Cr) |
22.0 – 23.0 |
24.0 – 26.0 |
21.5 – 24.5 |
24.0 – 26.0 |
| Nickel (Ni) |
4.5 – 6.5 |
6.0 – 8.0 |
3.0 – 5.5 |
6.0 – 8.0 |
| Molybdenum (Mo) |
3.0 – 3.5 |
3.0 – 5.0 |
0.05 – 0.60 |
3.0 – 4.0 |
| Nitrogen (N) |
0.14 – 0.20 |
0.24 – 0.32 |
0.05 – 0.20 |
0.20 – 0.30 |
| Copper (Cu) |
— |
≤ 0.50 |
— |
0.50 – 1.00 |
| Tungsten (W) |
— |
— |
— |
0.50 – 1.00 |
PREN (Pitting Resistance Equivalent Number) by Grade
| Grade |
PREN |
Corrosion Resistance Level |
| 316L (Austenitic - for reference) |
23 – 25 |
Standard |
| 2304 (Lean Duplex) |
24 – 26 |
Good (alternative to 316L) |
| 2205 (Standard Duplex) |
33 – 35 |
Excellent |
| S32760 (Super Duplex) |
40 – 42 |
Superior |
| 2507 (Super Duplex) |
41 – 45 |
Superior |
PREN = %Cr + 3.3(%Mo) + 16(%N). Higher PREN indicates better pitting resistance.
Mechanical Properties
| Grade |
Tensile Strength (MPa) |
Yield Strength (MPa) |
Elongation (%) |
Hardness (HB) |
| 2304 |
≥ 600 |
≥ 400 |
≥ 25 |
≤ 290 |
| 2205 |
≥ 620 |
≥ 450 |
≥ 25 |
≤ 290 |
| 2507 |
≥ 730 |
≥ 550 |
≥ 20 |
≤ 310 |
| S32760 |
≥ 730 |
≥ 550 |
≥ 25 |
≤ 310 |
Note: The values above are for reference only. Please refer to the mill test certificate for actual data.
Key Corrosion Resistance Features
- High Chromium (21-26%) – Forms stable passive film for general corrosion resistance
- Molybdenum (up to 5%) – Provides exceptional pitting and crevice corrosion protection
- Nitrogen (0.05-0.32%) – Stabilizes austenite and enhances pitting resistance
- Low Carbon (≤0.03%) – Prevents intergranular corrosion after welding
- Balanced Microstructure – Ferrite phase stops SCC crack propagation
- High PREN – Quantitative measure of pitting resistance for material selection
Corrosion Resistance by Environment
| Environment |
304/316 |
2304 |
2205 |
2507 |
| Fresh Water |
Good |
Excellent |
Excellent |
Excellent |
| Tap Water / Potable Water |
Good |
Excellent |
Excellent |
Excellent |
| Brackish Water |
Fair |
Good |
Excellent |
Excellent |
| Seawater (Splash Zone) |
Poor |
Fair |
Good |
Excellent |
| Seawater (Full Immersion) |
Not recommended |
Limited |
Good |
Excellent |
| Chloride Solutions (<1000 ppm) |
Fair |
Good |
Excellent |
Excellent |
| Chloride Solutions (>1000 ppm) |
Poor |
Fair |
Good |
Excellent |
| Sour Service (H₂S) |
Not recommended |
Not recommended |
Good (NACE) |
Good (NACE) |
| Acidic Environments |
Poor |
Fair |
Good |
Good |
| Caustic Environments |
Good |
Good |
Good |
Good |
Applications by Corrosion Challenge
| Corrosion Challenge |
Recommended Grade |
Typical Application |
| Seawater Pitting |
2507 |
Seawater cooling pipes, offshore platforms |
| Chloride SCC |
2205 or 2507 |
Chemical plants, heat exchangers |
| Crevice Corrosion |
2507 |
Flanges, gasketed joints, submerged service |
| Sour Gas (H₂S) |
2205 (NACE) |
Oil and gas flow lines, downhole tubing |
| High Chloride + Low pH |
2507 |
Desalination, acid chloride service |
| Erosion from Solids |
2205 |
Slurry lines, mining applications |
| High Temperature Corrosion |
2507 |
FGD systems, geothermal wells |
NACE MR0175 / ISO 15156 Compliance
For sour service applications containing hydrogen sulfide (H₂S), duplex steel pipe can be supplied to NACE MR0175.
| Requirement |
2205 |
2507 |
| Maximum Hardness (HRC) |
≤ 28 |
≤ 28 |
| SSC Resistance |
Yes |
Yes |
| HIC Resistance |
Yes |
Yes |
| Sour Service Limit (H₂S partial pressure) |
Up to 10 psi (70 kPa) |
Up to 10 psi (70 kPa) |
| Certification |
NACE MR0175 3.1 |
NACE MR0175 3.1 |
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Need a pipe that can handle your most aggressive corrosive environment? We have the solution
