UNS S31803 Duplex Stainless Steel Pipe
Grade: UNS S31803 (Duplex 2205)
Type: Seamless & Welded
Size Range: 1/2" NB to 24" NB
Wall Thickness: Schedule 5S to XXS
quality control: Support for third-party inspections (SGS, TÜV, BV, etc.)
Packaging: Reliable packaging (wooden crates, plastic caps, woven sacks)
S31803 is a standard duplex stainless steel grade (also known as 2205) featuring a balanced microstructure of approximately 50% austenite and 50% ferrite. This structure provides an exceptional combination of high strength, excellent corrosion resistance (particularly against chloride stress corrosion cracking), and good weldability. UNS S31803 Duplex Stainless Steel Pipe
is widely used in aggressive environments where standard austenitic grades (e.g., 304/316) are insufficient.
Key Features
High Strength:
Approximately twice the yield strength of standard austenitic stainless steels (e.g., 316L), allowing for reduced wall thickness and weight savings.
Excellent Corrosion Resistance:
Outstanding resistance to pitting, crevice corrosion, and stress corrosion cracking (SCC) in chloride-containing environments.
Cost-Effective:
Offers a performance-to-cost advantage over high-alloy austenitic and nickel-based alloys in many applications.
Good Weldability:
Can be welded using common methods, though care must be taken to maintain the austenite-ferrite balance.
Specifications & Standards
ASTM A789/A790:
Standard specification for seamless and welded duplex stainless steel tubes.
ASME SA789/SA790:
Equivalent for pressure applications.
EN 10216-5:
Seamless stainless steel tubes for pressure purposes.
NACE MR0175/ISO 15156:
Suitable for sour service (H₂S environments) under specific conditions.
Specifications
|
Parameter |
Specification |
|
Standard |
ASTM A790/A928 |
|
Grade |
UNS S31803 (Duplex 2205) |
|
Type |
Seamless & Welded |
|
Size Range |
1/2" NB to 24" NB |
|
Wall Thickness |
Schedule 5S to XXS |
|
Length |
Random 5-7 meters or cut-to-length |
Chemical Composition (%)
|
Element |
Requirements |
Typical Value |
|
Carbon (C) |
≤ 0.030 |
0.015 |
|
Chromium (Cr) |
21.0-23.0 |
22.0 |
|
Nickel (Ni) |
4.5-6.5 |
5.5 |
|
Molybdenum (Mo) |
2.5-3.5 |
3.0 |
|
Nitrogen (N) |
0.08-0.20 |
0.16 |
|
Manganese (Mn) |
≤ 2.00 |
1.2 |
|
Silicon (Si) |
≤ 1.00 |
0.5 |
|
Iron (Fe) |
Balance |
Balance |
Mechanical Properties
|
Property |
Requirements |
Typical Value |
|
Tensile Strength |
≥ 620 MPa |
750 MPa |
|
Yield Strength |
≥ 450 MPa |
550 MPa |
|
Elongation |
≥ 25% |
30% |
|
Hardness (Brinell) |
≤ 293 HB |
240 HB |
Equivalent Grades
|
Standard System |
UNS |
EN (DIN) |
JIS |
|
Grade |
S31803 |
1.4462 |
SUS 329J3L |
Quality Assurance of UNS S31803 Duplex Stainless Steel Pipe
- Mill Test Certificate EN 10204 3.1
- Hydrostatic Testing per ASTM Standards
- Solution Annealing & Quenching
- Ferrite Content Verification (35-55%)
- Intergranular Corrosion Testing
- Third-Party Inspection Welcome
Applications
Oil & Gas
Downhole tubing, flow lines, piping systems in offshore and sour service environments.
Chemical Processing
Heat exchangers, pressure vessels, reactors handling corrosive chemicals.
Desalination Plants
Seawater piping and heat recovery systems.
Pulp & Paper Industry
Digester vessels and bleaching equipment.
Marine and Offshore
Seawater cooling systems, structural components.
Fabrication Notes
Welding:
Use matching duplex filler metals (e.g., ER2209) and control heat input to avoid excessive ferrite formation.
Heat Treatment:
Solution annealing at 1020–1100°C (1868–2012°F) followed by rapid quenching to optimize the austenite-ferrite balance and corrosion resistance.
Machining:
Higher strength requires more power than austenitic grades; use positive rake tools and adequate cooling.
FAQ
Q: What is the main advantage of UNS S31803 over 316L?
A: UNS S31803 offers nearly double the yield strength and significantly better resistance to chloride stress corrosion cracking, making it suitable for more demanding applications.
Q: What is the maximum service temperature?
A: Maximum continuous service temperature is 300°C. Above this temperature, toughness may decrease.
Q: Is post-weld heat treatment required?
A: Generally not required for most applications when using proper welding procedures and matching filler metals.
Q: What is the PREN value of UNS S31803?
A: PREN (Pitting Resistance Equivalent Number) is typically 33-35, calculated as %Cr + 3.3×%Mo + 16×%N.
Q: Can you provide large-diameter pipes?
A: Yes, we can supply UNS S31803 Duplex Stainless Steel Pipe up to 24" NB in welded construction.
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Email:baohui@bhsteelpipe.com
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