2205 Seamless Duplex Steel Tube (UNS S32205)

UNS S32205 | 1.4462 | ASTM A789

2205 Seamless Duplex Steel Tube (UNS S32205) (S32205 / 1.4462) is manufactured to ASTM A789 from duplex steel (uns s32205) billet, cold-drawn to the required outside diameter and wall thickness. Supplied from our Wenzhou mill with EN 10204 3.1 mill test certificate, PMI and dimensional inspection on request.

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What Is a Seamless Duplex Steel UNS S32205 Tube?

UNS S32205, universally known as 2205 duplex, is the most widely used duplex stainless steel. Its 22% chromium, 3% molybdenum and 0.17% nitrogen give a PREN of about 35, roughly twice the yield strength of 304 or 316, and excellent resistance to chloride stress-corrosion cracking — the combination that made duplex the default material for chemical, oil and gas and desalination piping.

A Seamless Duplex Stainless Steel Tube UNS S32205 (commonly known as Duplex 2205 or W.Nr. 1.4462) is a high-performance nitrogen-alloyed duplex stainless steel tubing designed for demanding industrial environments.

Produced from a single solid billet through seamless hot or cold forming processes, these tubes contain no longitudinal weld seams, ensuring superior pressure resistance, structural integrity, and metallurgical uniformity compared with welded tubing.

The term “Duplex” refers to the alloy’s dual-phase microstructure, consisting of approximately:

This balanced structure provides an optimal combination of:

Duplex stainless steel UNS S32205 is considered an enhanced and tightly controlled version of UNS S31803, with optimized levels of Chromium (Cr), Molybdenum (Mo), and Nitrogen (N) to deliver improved corrosion resistance, mechanical performance, and weldability.

2205 Key Features and Technical Advantages

Duplex 2205 offers yield strength nearly twice that of conventional austenitic stainless steels such as 304Land316L, allowing engineers to design lighter structures with reduced wall thickness while maintaining structural safety.

The duplex microstructure provides excellent resistance to chloride-induced stress corrosion cracking (SCC), making UNS S32205 tubing ideal for warm, chloride-rich environments such as offshore and marine systems.

With its optimized chemical composition, Duplex 2205 typically achieves a Pitting Resistance Equivalent Number (PREN) ≥ 35, ensuring strong resistance to pitting and crevice corrosion in seawater and aggressive chemical media.

Feature	Description
High Mechanical Strength	Duplex 2205 offers yield strength nearly twice that of conventional austenitic stainless steels such as 304L and 316L, allowing engineers to design lighter structures with reduced wall thickness while maintaining structural safety.
Superior Stress Corrosion Cracking Resistance	The duplex microstructure provides excellent resistance to chloride-induced stress corrosion cracking (SCC), making UNS S32205 tubing ideal for warm, chloride-rich environments such as offshore and marine systems.
Enhanced Pitting and Crevice Corrosion Resistance	With its optimized chemical composition, Duplex 2205 typically achieves a Pitting Resistance Equivalent Number (PREN) ≥ 35, ensuring strong resistance to pitting and crevice corrosion in seawater and aggressive chemical media.
PREN Formula	PREN = %Cr + 3.3 × %Mo + 16 × %N
Lower Thermal Expansion	Duplex 2205 has a thermal expansion coefficient closer to carbon steel than austenitic stainless steel, reducing thermal stress, distortion, and fatigue in heat exchanger and high-temperature process equipment.
Excellent Toughness at Low Temperatures	Seamless UNS S32205 tubes maintain good mechanical properties and impact toughness at temperatures down to –50°C, making them suitable for low-temperature and offshore environments.
Technical Specifications and Standards	Our Seamless Duplex Steel UNS S32205 / 1.4462 Tubes are supplied in accordance with major international standards:

2205 Product Specifications and Data

ASTM A789 – Seamless and Welded Duplex Stainless Steel Tubing
ASTM A790 – Seamless and Welded Duplex Stainless Steel Pipe
ASME SA789 / SA790

Corrosion Resistance Index

PREN ≥ 35

This ensures excellent performance in chloride-containing environments and aggressive industrial media.

Here are the detailed technical specifications and performance data for S32205 Duplex Stainless Steel.

The key feature is the high Chromium and Molybdenum content, combined with the Nitrogen addition which stabilizes the austenite phase and boosts localized corrosion resistance.

Grade	C	Mn	P	S	Si	Ni	Cr	Mo	N	Cu	Others
31803	≤0.03	≤2.00	≤0.03	≤0.02	≤1.00	4.50-6.50	21.00-23.00	2.50-3.50	0.08-0.20	…	…
32205	≤0.03	≤2.00	≤0.03	≤0.02	≤1.00	4.50-6.50	22.00-23.00	3.00-3.50	0.14-0.20	…	…
31500	≤0.03	1.20-2.00	≤0.03	≤0.03	1.40-2.00	4.3-5.2	18.00-19.00	2.50-3.00	0.05-0.10	…	…
32550	≤0.04	≤1.50	≤0.04	≤0.03	≤1.00	4.50-6.50	24.00-27.00	2.90-3.90	0.10-0.25	1.50-2.50	…
32750	≤0.03	≤1.20	≤0.035	≤0.02	≤0.80	6.00-8.00	24.00-26.00	3.00-5.00	0.24-0.32	≤0.50	…
32760	≤0.03	≤1.00	≤0.030	≤0.01	≤1.00	6.00-8.00	24.00-26.00	3.00-4.00	0.20-0.30	0.50-1.00	W 0.50 -1.00
32950	≤0.03	≤2.00	≤0.035	≤0.01	≤0.60	3.50-5.20	26.00-29.00	1.00-2.50	0.15-0.35	…	…
32906	≤0.03	0.80-1.50	≤0.030	≤0.03	≤0.50	5.80-7.50	28.00-30.00	1.50-2.60	0.30-0.40	≤0.80	…

Tensile Strength	Yield Strength	Elongation	Hardness
≥ 655 MPa	≥ 485 MPa	≥ 25%	≤ 293 HBW

Density	Melting Point	Thermal Expansion	Thermal Conductivity
7.82 g/cm³	1385-1440 ℃	13.0 µm/m·℃	14.6 W/m·K

Specified Outside Diameter (OD) (Inches)	Permissible Variations in OD (± Inches)
1⁄2 to 1	±0.005
Over 1 to 1-1⁄2	±0.008
Over 1-1⁄2 to 2	±0.010
Over 2 to 2-1⁄2	±0.012
Over 2-1⁄2 to 3-1⁄2	±0.014
Over 3-1⁄2 to 5	±0.020

Specified Outside Diameter (OD) (Inches)	Specified Wall Thickness (WT) (Inches)	Permissible Variation (± Inches)
1⁄2 to 1 (Inclusive)	0.025 to 0.065(Inclusive)	±0.010
	Over 0.065to 0.134 (Inclusive)	±0.012
Over 1 to 1-1⁄2 (Inclusive)	0.025 to 0.065 (Inclusive)	±0.010
	Over 0.065 to 0.134 (Inclusive)	±0.012
Over 1-1⁄2 to 2 (Inclusive)	0.025 to 0.049 (Inclusive)	±0.011
	Over 0.049 to 0.083 (Inclusive)	±0.012
	Over 0.083 to 0.148 (Inclusive)	±0.014
Over 2 to 2-1⁄2 (Inclusive)	0.032 to 0.065 (Inclusive)	±0.013
	Over 0.065 to 0.109 (Inclusive)	±0.015
	Over 0.109 to 0.165 (Inclusive)	±0.017
Over 2-1⁄2 to 3-1⁄2 (Inclusive)	0.032 to 0.165 (Inclusive)	±0.020
	Over 0.165 to 0.220 (Inclusive)	±0.025
Over 3-1⁄2 to 5 (Inclusive)	0.083 to 0.165 (Inclusive)	±0.025
	Over 0.165 to 0.220 (Inclusive)	±0.030

100% Positive Material Identification (PMI)

Corrosion Resistance Testing

Intergranular Corrosion Testing (IGC)
Pitting Corrosion Testing according to ASTM G48

Mechanical Testing

Impact testing
Flattening test
Flare test
Bend test
Hardness testing

These rigorous procedures ensure reliable performance in high-pressure, corrosive, and mission-critical industrial environments.

	Microstructure	Yield Strength	Tensile Strength	Density	Pitting Resistance (PREN)	Chloride SCC Resistance	Corrosion Resistance	Thermal Expansion	Maximum Service Temperature	Weldability	Cost	Typical Applications
Duplex 2205 (UNS S32205 / 1.4462)	Duplex (≈50% Ferrite + 50% Austenite)	~450 MPa	~620–880 MPa	7.8 g/cm³	≥ 35	Excellent	Excellent in chloride and marine environments	Lower (closer to carbon steel)	~300°C (for pressure service)	Good (requires controlled heat input)	Higher initial material cost	Offshore, seawater systems, chemical processing, desalination
316L Stainless Steel (UNS S31603 / 1.4404)	Fully Austenitic	~170 MPa	~485–620 MPa	8.0 g/cm³	~24	Moderate to Poor	Good in general corrosion environments	Higher	~400°C	Excellent	Lower material cost	Food processing, pharmaceutical equipment, chemical tanks

2205 Dimensional Standards and Tolerances

S32205 duplex seamless tubes are supplied to the dimensional tolerances of ASTM A789 / A1016 unless a tighter project specification applies.

For Specific Cut Lengths, the standard tolerance is +1⁄8 in. [3 mm], -0 in. [0 mm].

Important Note: The values presented here are based on the common tables in the ASTM A789 standard. The full specification, particularly the referenced ASTM A1016/A1016M (General Requirements for Ferritic Alloy Steel, Austenitic Alloy Steel, and Stainless Steel Tubes), contains other essential requirements like straightness and details for tubes with ODs outside of this range. Always consult the latest official standard for design and procurement.

2205 Common Industrial Applications

Industry	Typical Applications
Oil and Gas Industry	Flowlines and process piping Subsea and topside equipment Sour service lines
Chemical Processing	Reactors, vessels and heat exchangers Chloride-bearing process streams Storage and transfer piping
Desalination and Marine Engineering	RO high-pressure piping Seawater intake and brine lines Shipboard piping systems
Pulp and Paper Industry	Digester and liquor handling Bleach plant piping Heat exchangers

2205 Quality Assurance and Production Process

Process Step	Description
Certification	All Duplex S32205 tubes are supplied to ASTM A789 / ASME SA789 and ASTM A790 / ASME SA790 with EN 10204 3.1 mill test certificates. Third-party inspection (SGS, BV, TUV, Lloyd's), PMI reports and full heat-number traceability can be provided on request.
Non-Destructive Testing (NDT)	Hydrostatic or eddy-current testing is performed on 100% of tubes. Ultrasonic testing (UT) and dye-penetrant inspection (PT) are available for critical service, with records retained for each production lot.
Material Verification	Positive Material Identification (PMI) and spectrometric analysis confirm that the chemical composition matches the ordered grade and that the ferrite/austenite balance is within the specified range.
Mechanical Testing	Tensile, yield, elongation and hardness tests are carried out per heat. Impact testing can be supplied at the project design temperature for subsea and low-temperature service.
Dimensional Inspection	Outside diameter, wall thickness, ovality and straightness are measured against ASTM A1016 / A1016M or ASTM A789 tolerances. Length, square-cut ends and end-finish conditions are verified before packing.

S32205 (2205) vs S31803 – Technical Comparison

S32205 and S31803 are the two designations of 2205 duplex. They are closely related, and the difference lies in tighter compositional control.

Chemical Composition

S31803: the original 2205 composition, with wider compositional ranges
S32205: a tighter version with higher minimum chromium, molybdenum and nitrogen
S32205 was introduced to guarantee a more consistent PREN

Corrosion Resistance

Because S32205 sets higher minimum contents for the alloying elements that drive PREN, it delivers more consistent pitting and crevice resistance from heat to heat. In practice S31803 material within its range can meet the same performance, but the guarantee is weaker.

Mechanical Strength

The two grades have essentially the same mechanical properties, both delivering roughly twice the yield strength of 304 or 316.

Selection Guide

Specify S32205 for new projects — it is the current standard and gives more predictable corrosion performance
S31803 remains acceptable where an existing specification or drawing calls for it
Duplex 2205 is a cost-effective substitute for 316L in chloride service and for 904L in many duties

Frequently Asked Questions About 2205 Seamless Duplex Steel Tube (UNS S32205)s

What is UNS S32205 duplex tube?

UNS S32205, universally known as 2205 duplex, is the most widely used duplex stainless steel. With 22% chromium, 3% molybdenum and 0.17% nitrogen it achieves a PREN of about 35 and roughly twice the yield strength of 304 or 316.

What is the difference between S32205 and S31803?

Both are 2205 duplex. S32205 sets higher minimum contents for chromium, molybdenum and nitrogen, which guarantees a more consistent PREN from heat to heat. Mechanical properties are essentially the same.

What standard covers S32205 tube?

S32205 seamless tube is supplied to ASTM A789 / ASME SA789 for tubing and ASTM A790 / ASME SA790 for pipe, with dimensional tolerances per ASTM A1016 / A1016M.

What is S32205 tube used for?

S32205 is used for oil and gas flowlines and process piping, chemical reactors and heat exchangers, reverse-osmosis high-pressure piping, shipboard seawater systems and pulp and paper process lines.

Request a 2205 Tube Quotation

Send your Seamless Duplex Steel UNS S32205 Tube enquiry with grade, application, size (OD and wall thickness or schedule), quantity, length, end finish and inspection requirements. Our technical team will confirm availability, testing scope and lead time.

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