ASTM A790 S31803 Duplex Stainless Seamless Steel Pipe

STM A790 UNS S31803 (2205)is the most widely usedduplex stainless steel seamless pipe, featuring a balanced ferritic-austenitic microstructure. It combineshigh strength,excellent pitting/crevice corrosion resistance, andsuperior stress corrosion cracking (SCC) resistancein chloride-rich environments.

·Common Name: 2205 Duplex Stainless Steel

·Material Grade: UNS S31803 / S32205

·Standard: ASTM A790 / ASME SA790

·Process: Hot-finished / Cold-drawn seamless

·Certification: EN 10204 3.1 / 3.2, PMI, NDT Certified

Technical Specifications

1 Chemical Composition (wt%, Max)

2 Mechanical Properties (Room Temp)

3 Dimensions & Range

·Nominal Size: 1/2" NB - 16" NB (OD 21.3mm - 406.4mm)

·Wall Thickness: SCH 5, 10, 40, 80, 160, XS, XXS

·Length: 5.8m / 6m or custom length (17-40 ft random lengths)

·Ends: Plain End (PE), Beveled End (BE), NPT Threaded

Surface: Pickled, Sandblasted, Polished, BA, EP

Standard seaworthyexport packagingto ensure safe delivery:
Bundle Packing: Pipes bundled with steel straps (6-12 pcs/bundle), marked with grade, size, heat number.
End Protection: Plastic caps (PE/BE ends) or thread protectors (NPT ends).
Moisture Barrier: Wrapped in waterproof kraft paper or plastic film.
Outer Packing: Plywood crates / wooden boxes for small sizes; steel frames for large diameters.
Marking: Each pipe stenciled with standard, grade, size, heat number, logo, and destination.

Key Features:

✅Superior Corrosion Resistance: Resists pitting, crevice, and SCC in seawater, brines, and acidic media (PREN ≥ 35).
✅High Mechanical Strength: ~2x yield strength of 316L, enabling thinner walls and cost savings.
✅Cost-Effective: Lower nickel content than austenitic grades (e.g., 316L), offering stable pricing.
✅Good Fabricability: Easy to weld, bend, and machine with proper procedures.

Corronsion Resistance:Excellent general corrosion resistance; superior to Grade 316 in most environments. Excellent resistance to localised corrosion including intergranular, pitting and crevice corrosion; the CPT of 2205 is generally at least 35°C. The grade is also resistant to chloride stress corrosion cracking (SCC) at temperatures of up to about 150°C. Grade 2205 will often perform well in environments which cause premature failure of austenitic grades. It has better resistance to sea water than grade 316.

Heat Resistance:Although 2205 has good high temperature oxidation resistance this grade, like other duplex stainless steels, suffers from embrittlement if held for even short times at temperatures above 300°C. If embrittled this can only be rectified by a full solution annealing treatment. Duplex stainless steels are almost never used above 300°C.

Applications

by Oil & Gas
Offshore platforms, subsea pipelines, risers, flowlines
Wellhead equipment, downhole tubing, saltwater injection lines
"Chemical Processing
Heat exchangers, pressure vessels, reactor piping
Chloride-rich processes, bleach plants, acid handling systems
by Marine & Desalination
Seawater cooling lines, desalination plant piping (RO systems)
Shipbuilding, coastal infrastructure, ballast water systems
by Pulp & Paper
Digester lines, bleach washers, black liquor recovery systems
by Other
Food processing, pharmaceutical, power generation (FGD systems)

FAQ

Q1: What is the difference between S31803 and S32205?

A: Both are 2205 duplex grades.S32205has tighter control of nitrogen (0.17-0.22%) and higher PREN, preferred for critical offshore/chemical service.S31803is the standard, widely available grade.

Q2: Can S31803 be used at high temperatures?

A:Continuous service ≤ 300°C (572°F). Prolonged exposure above 300°C causes sigma-phase embrittlement, reducing toughness.

Q3: What NDT tests are performed?

A: 100%Ultrasonic Testing (UT)andEddy Current Testing (ET);Hydrostatic Testing(pressure per ASME B36.10);PMIfor material verification.

Q4: Is welding difficult?

A: UseE2209 electrodesorER2209 filler wire. Avoid prolonged high heat input; no post-weld heat treatment (PWHT) required.

Q5: What is the typical lead time?

A:Standard sizes: 2-3 weeks;Custom sizes: 4-6 weeks. FOB Tianjin / Shanghai, China.

Q: What is PMI test?
A: PMI stands for Positive Material Identification. It is a non-destructive spectral analysis to check chemical composition on site, ensuring the delivered pipes are strictly compliant with UNS S31803 duplex stainless steel grade. It is a mandatory inspection for oil & gas and chemical projects.