Duplex 2205 (UNS S31803 / S32205)
Duplex 2205 features a balanced 50/50 dual-phase microstructure of austenite and ferrite. It provides roughly twice the mechanical yield strength of standard austenitic stainless steels, combined with remarkable resistance to chloride stress corrosion cracking, pitting, and erosion in Qatar’s marine and desalination facilities.
Material Quick Reference
| Material Classification | Austenitic-Ferritic Duplex Stainless Steel (22% Cr, 5% Ni, 3% Mo, 0.17% N) |
|---|---|
| Pitting Resistance (PREN) | 35 - 36 |
| Temperature Limits | -50°C to +280°C |
| Governing Specifications | ASTM A790 (Seamless & Welded Pipe), ASTM A815 (Fittings), ASTM A182 F51 / F60, NACE MR0175 / ISO 15156 |
Typical Engineering Applications
- Seawater Reverse Osmosis (SWRO) high-pressure feed piping
- Offshore oil and gas process headers and risers
- Sour gas gathering lines containing chlorides and CO2
- Marine cargo piping on chemical tankers
Chemical Environment & Corrosion Resistance
High pitting resistance in saline waters (chlorides up to 30,000 ppm at moderate temperatures) and high resistance to H2S sour cracking.
Performance in Qatar's Coastal & Industrial Climate
The primary material of choice for SWRO desalination plants (Ras Abu Fontas, Umm Al Houl) and offshore platforms in Qatar.
Welding & Fabrication Guidelines
Requires specialized WPS/PQR using over-alloyed ER2209 wire. Heat input tightly controlled between 0.5 and 1.5 kJ/mm to maintain 40–60% ferrite balance.
Positive Material Identification (PMI) Requirements
XRF testing for 22% Cr, 5% Ni, 3% Mo; Ferrite scope verification of weld metal (35–65% ferrite).
Key Advantages
- Yield strength > 450 MPa (enables thinner pipe walls)
- High resistance to chloride SCC and erosion-corrosion
Engineering Limitations
- Operating temperature limited to 280°C max to prevent 475°C embrittlement; prone to sigma phase if cooled too slowly
Related Products & Contracting Services
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