Duplex Steel 2205 (UNS S32205 / S31803) Pipe Fittings & Flanges Manufacturer
PED 2014/68/EU & ISO 9001 Certified. Delivering high-PREN duplex solutions for desalination, oil & gas, and chemical processing environments worldwide.
- Dual Certified: Meeting both UNS S31803 and S32205 standards.
- High Performance: Enhanced Nitrogen for PREN >35 and superior weldability.
- Full Traceability: EN 10204 3.1 MTC with 100% PMI testing.
Data verified against NACE MR0175 / ISO 15156 for sour service applications. Values provided are typical for Sunhyings production.
1. Duplex 2205 Overview: S31803 vs S32205
Duplex 2205 is a nitrogen-enhanced duplex stainless steel consisting of approximately 50% ferrite and 50% austenite. This mixed microstructure provides a unique combination of high strength (twice that of 304/316) and excellent corrosion resistance.
While often used interchangeably, there is a distinct difference between the two common UNS designations:
- UNS S31803: The original specification for 2205.
- UNS S32205: The modern, "restricted chemistry" version. It requires higher minimum limits for Chromium, Molybdenum, and Nitrogen.
Sunhyings Policy: We primarily stock and manufacture Dual Certified (S31803/S32205) material. By meeting the stricter S32205 chemistry, we ensure better corrosion resistance and optimized phase balance after welding.
2. Chemical Composition & PREN Value
The addition of Nitrogen is critical for stabilising the austenite phase during welding. See how Sunhyings internal standards compare to the generic specs.
| Element | UNS S31803 (Min) | UNS S32205 (Min) | Sunhyings Typical | Effect |
|---|---|---|---|---|
| Chromium (Cr) | 21.0% | 22.0% | 22.5% | Basic corrosion resistance. |
| Molybdenum (Mo) | 2.5% | 3.0% | 3.2% | Resistance to pitting & crevice corrosion. |
| Nitrogen (N) | 0.08% | 0.14% | 0.17% | Increases strength & pitting resistance; stabilizes austenite. |
| Nickel (Ni) | 4.5% | 4.5% | 5.6% | Toughness & phase balance. |
PREN Formula: PREN = %Cr + 3.3(%Mo) + 16(%N)
Sunhyings guarantees a PREN ≥ 35 for our S32205 products, ensuring superior resistance to seawater pitting compared to standard S31803 (PREN ~33).
3. Manufacturing Range: Fittings & Flanges
We manufacture a complete line of pipe components in Wenzhou, covering both butt weld and forged types.
Butt Weld Fittings (ASTM A815 / ASME B16.9)
| Types | Elbows (45°/90°/180°, LR/SR), Tees (Equal/Reducing), Concentric & Eccentric Reducers, Stub Ends, End Caps. |
| Size Range | 1/2" to 48" (Seamless up to 24", Welded 26"-48") |
| Thickness | SCH 10S, SCH 40S, SCH 80S, SCH 160, XXS. |
Forged Fittings & Flanges (ASTM A182)
| Flanges (B16.5) | Weld Neck (WN), Slip-on (SO), Blind, Socket Weld (SW), Threaded. Class 150# to 2500#. |
| Forged Fittings (B16.11) | Socket Weld & Threaded (NPT/BSP) Elbows, Tees, Unions, Couplings. Rating: 3000#, 6000#, 9000#. |
4. Mechanical Properties (Room Temp)
Duplex 2205 allows engineers to design with thinner walls due to its high yield strength, often leading to weight and cost savings compared to 316L.
| Property | Value (Min) | Notes |
|---|---|---|
| Tensile Strength (Rm) | ≥ 655 MPa (95 ksi) | Approx. 25% higher than 316L. |
| Yield Strength (0.2%) | ≥ 450 MPa (65 ksi) | Double the strength of 316L (205 MPa). |
| Elongation | ≥ 25% | Good ductility for forming. |
| Hardness | ≤ 290 HB / 31 HRC | Compliant with NACE MR0175 limits. |
5. Applications & Corrosion Performance
Why choose 2205? It solves the problem of Stress Corrosion Cracking (SCC) that plagues 304/316 in hot chloride environments.
Desalination (SWRO)
With PREN >34, 2205 is the industry standard for high-pressure piping in Reverse Osmosis plants, handling seawater where 316L would fail from pitting.
Oil & Gas (Sour Service)
Approved for use in sour environments (H2S-containing) per NACE MR0175 / ISO 15156. High resistance to sulfide stress cracking.
Chemical Processing
Excellent performance in acetic acid, formic acid, and PVC production environments. Superior abrasion resistance for slurry handling.
6. Welding & Fabrication Guide
Welding 2205 requires more technical control than 304/316 to maintain the austenite-ferrite balance.
- Filler Metal: Always use ER2209 (over-alloyed with Ni) to promote austenite formation in the weld. Autogenous welding (without filler) is not recommended.
- Heat Input: Strictly control between 0.5 – 2.5 kJ/mm.
- Too low = High ferrite (loss of corrosion resistance).
- Too high = Sigma phase precipitation (embrittlement).
- Interpass Temperature: Maximum 150°C.
- Shielding Gas: Ar + 1-2% N2 is recommended to compensate for nitrogen loss.
7. Quality Assurance & MTC
Trust is built on transparency. Every shipment from Sunhyings includes detailed documentation.
- MTC: EN 10204 3.1 Certificate including chemical analysis, tensile test, hardness test, and heat treatment batch.
- Non-Destructive Testing (NDT):
- 100% PMI (Positive Material Identification) to prevent material mix-up.
- Radiography (RT) or Ultrasonic (UT) for welded fittings as per ASME/ASTM.
- Corrosion Testing: ASTM G48 Method A (Pitting test) available upon request.
8. FAQ: Duplex 2205 Questions
Yes. Unlike 304 or 316 austenitic stainless steels, Duplex 2205 has a ferromagnetic structure due to its ~50% ferrite content. It will strongly attract a magnet.
Duplex 2205 is generally limited to 300°C (572°F) maximum. Long-term exposure above this temperature (specifically 475°C) causes "475°C embrittlement," drastically reducing toughness.
No. Using 316L filler will result in a weld with much lower strength and corrosion resistance than the 2205 base metal. You must use ER2209 or E2209 filler.
9. Talk to a Sunhyings Engineer
Need a quote for S32205 Flanges or Fittings? Send us your bill of materials. We reply within 24 hours with stock availability and pricing.
Resources
- Duplex 2205 Technical Datasheet (PDF)
- Sunhyings ISO 9001 & PED Certificates
- ASTM A182 / A815 Dimensional Tolerances