Key Feature

The High-Strength Duplex Corrosion-Resistant Piping Solution. Dual-phase microstructure provides approximately double the yield strength of 316L with superior chloride stress corrosion cracking resistance.

The workhorse duplex grade offering optimal balance of strength, corrosion resistance, and cost-effectiveness.

Common Designations

UNS S31803/S32205
ASTM A790/A928 (Duplex Pipe)
EN 1.4462, X2CrNiMoN22-5-3
SAF 2205™
JIS SUS329J3L

S32205 is the leaner, more common variant; S31803 has slightly different chemistry limits.

Chemical Composition (Typical wt.%)

C: ≤ 0.030
Cr: 22.0 - 23.0Ni: 4.5 - 6.5
Mo: 3.0 - 3.5N: 0.14 - 0.20Mn: ≤ 2.00
Si: ≤ 1.00

Nitrogen addition is critical for austenite formation and strength enhancement.

Mechanical Properties

Tensile Strength: ≥ 620 MPa
Yield Strength: ≥ 450 MPa
Elongation: ≥ 25%
Hardness: ≤ 293 HB
Impact Toughness: ≥ 100 J at -40°C

Approximately double the yield strength of 316L, allowing for weight reduction.

Physical Properties

Density: 7.80 g/cm³
Melting Range: 1400 - 1450 °C
Thermal Expansion: 13.7 × 10⁻⁶/K (20-100°C)
Thermal Conductivity: 19 W/m·K
Magnetic (due to ferrite phase)

Lower thermal expansion than austenitics reduces thermal stress.

Corrosion Resistance

Exceptional: PREN*: 34-36
Excellent resistance to: chloride stress corrosion cracking, pitting, crevice corrosion, erosion-corrosion.

Superior to 316L in chloride-containing environments; comparable to some 6% Mo austenitics.

Pressure Ratings

Schedule 10S/40S: Standard
Schedule 80S/160: Heavy wall
ASME B31.3 compliant
Allowable stresses higher than austenitics

Higher strength allows for reduced wall thickness and weight savings.

Temperature Limits

Continuous Service: Up to 300°C
Maximum Service: 315°C
Minimum Service: -50°C
Avoid: 300-1000°C (embrittlement risk)

Limited high-temperature service due to embrittlement concerns.

Welding Characteristics

Requires controlled procedures
Maintain phase balance critical
Overmatched filler metals (higher alloy)
Heat input control essential
No preheat required

More demanding than austenitic welding but well-established procedures exist.

Key Standards

ASTM A790: Seamless & Welded Duplex Pipe
ASTM A928: EFW Duplex Pipe
ASTM A789: Seamless & Welded Tubing
NORSOK M-630: Offshore materials
EN 10216-5: Seamless Pressure Tubes

Industry-recognized standards for quality assurance.

Common Applications

• Oil & Gas: Flowlines, risers, process piping, seawater systems
• Chemical Processing: Acid piping, chloride-containing process streams
• Pulp & Paper: Digester piping, bleach plants, chemical recovery
• Marine/Offshore: Seawater piping, firewater systems, ballast lines
• Power Generation: FGD systems, cooling water piping
• Water Treatment: Desalination plants, chlorinated water systems
• Mining: Slurry piping, process water systems

Specifically selected for aggressive chloride-containing environments requiring high strength.