UNS S32750|1.4410|2507 Seamless Super Duplex Steel Tube

Seamless Super Duplex UNS S32750 Tube (Alloy 2507 / EN 1.4410)
Seamless Super Duplex Steel S32750 Tubes are high-performance piping solutions engineered with a precisely balanced austenitic-ferritic microstructure (50:50) for mission-critical durability. As a premier manufacturer based in Wenzhou, China, XinZhe specializes in precision-engineered seamless tubing that strictly complies with global industry standards, including ASTM A789, ASTM A790, and NORSOK M650.
Superior Corrosion Resistance & Metallurgy
Specifically designed for the most aggressive chloride-rich environments, our S32750 (2507) tubes are metallurgically optimized to achieve a high Pitting Resistance Equivalent Number (PREN ≥ 41). This superior threshold ensures exceptional resistance against:
• Pitting and Crevice Corrosion in hot seawater.
• Chloride Stress Corrosion Cracking (SCC).
• Erosion-Corrosion in high-flow offshore applications.
The PREN is strictly controlled via the following chemical equilibrium:

PREN = %Cr + 3.3X%Mo + 16 X%N ≥41

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What Is a Seamless Super Duplex UNS S32750 Tube?

UNS S32750, also designated EN 1.4410 and commonly called 2507, is the reference super duplex stainless steel. Its 25% chromium, 4% molybdenum and high nitrogen content produce a PREN above 40 together with roughly twice the yield strength of standard austenitic grades, which allows thinner walls and lighter structures in high-pressure seawater and subsea duty.

Key Features and Technical Advantages

The Seamless Super Duplex UNS S32750 Tube (EN 1.4410 / Super Duplex 2507) is a premium-grade stainless steel pipe designed for demanding applications involving high pressure, aggressive chloride environments, and critical fluid transmission systems.

Manufactured from a single solid billet through a seamless process, this tube eliminates weld seams, ensuring uniform mechanical properties, superior pressure resistance, and enhanced operational safety compared to welded alternatives.

UNS S32750 is a Super Duplex Stainless Steel (SDSS) with a balanced 50% austenite and 50% ferrite microstructure, combining the advantages of both phases—high strength and outstanding corrosion resistance.

1. Exceptional Corrosion Resistance

Pitting corrosion
Crevice corrosion
Chloride Stress Corrosion Cracking (SCC)

2. High Strength & Lightweight Design

Reduced wall thickness
Lower material weight
Cost-efficient structural design

3. Excellent Toughness & Durability

Sub-zero temperatures
Ambient and elevated temperatures

4. Seamless Structural Integrity

No weld seam defects
No heat-affected zone (HAZ)
Higher pressure ratings and reliability in critical systems

Product Specifications and Data

UNS S32750 achieves its “Super Duplex” classification through a high-alloy composition:

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	…

NOTE: PREN:Cr+3.3*Mo+16*N≥41

UNS S32750 / 1.4410 is specifically designed to maintain its strength and shape in high-stress, corrosive environments.

Tensile Strength	Yield Strength	Elongation	Hardness
≥ 800 MPa	≥ 550 MPa	≥ 25%	≤ 290 HBW

Density	Melting Point	Thermal Expansion	Thermal Conductivity	Modulus of Elasticity	Electrical Resistivity
7.8 g/cm³	1450 °C approx.	13.5 µm/m·°C (20-100°C)	15.0 W/m·K (20°C)	200 GPa	0.85 x 10⁻⁶ Ω·m (20°C)

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

Dimensional Standards and Tolerances

S32750 super 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.

Common Industrial Applications

Oil and Gas Industry

Subsea manifolds and flowlines
Sour service piping
High-pressure process equipment

Desalination Plants

RO high-pressure piping
Brine handling systems
Multi-stage flash evaporators

Chemical Processing

Reactors and heat exchangers
Chloride-bearing process lines
Acid handling equipment

Marine and Offshore Engineering

Seawater cooling systems
Firewater and deluge piping
Offshore platform pipework

Quality Assurance and Manufacturing Process

Certification

All Super Duplex S32750 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.

S32750 (2507) vs S32205 (2205) – Technical Comparison

S32750 super duplex and S32205 standard duplex are the two most common duplex choices. The selection usually turns on how aggressive the chloride environment is.

Chemical Composition and PREN

S32750: ~25% Cr, ~4% Mo, ~0.3% N — PREN above 40
S32205: ~22% Cr, ~3% Mo, ~0.17% N — PREN about 35
The higher alloy content of S32750 is what buys the additional margin

Corrosion Resistance

S32750 resists pitting and crevice attack at higher chloride concentrations and temperatures than S32205, and tolerates more aggressive sour service. Where S32205 is near its critical pitting temperature, S32750 typically still has margin.

Mechanical Strength

Both deliver roughly twice the yield strength of 316L. S32750 is usually slightly stronger, and its higher alloy content allows use at somewhat higher temperature before the austenite-ferrite balance becomes unfavourable.

Selection Guide

Choose S32750 for the most severe chloride service, high-temperature seawater and demanding subsea duty
Choose S32205 for the broad middle ground of chemical, oil and gas and desalination piping where it has decades of service experience
Confirm the critical pitting temperature of the actual service before deciding

Frequently Asked Questions

What is UNS S32750 super duplex tube?

UNS S32750, also designated EN 1.4410 and commonly called 2507, is the reference super duplex stainless steel. Its 25% chromium, 4% molybdenum and high nitrogen give a PREN above 40 together with roughly twice the yield strength of austenitic grades.

What is the difference between S32750 and S32205?

S32750 is a super duplex with PREN above 40; S32205 (2205) is a standard duplex with PREN about 35. S32750 resists pitting and crevice attack at higher chloride concentrations and temperatures and tolerates more aggressive sour service, at higher alloy cost.

What standard covers S32750 tube?

S32750 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 S32750 tube used for?

S32750 is used for subsea manifolds and flowlines, sour service piping, reverse-osmosis high-pressure piping, desalination evaporators, and offshore seawater cooling systems.

Ready to Request a Quotation?

Send your Seamless Super Duplex UNS S32750 Tube enquiry with grade, application, size (OD and wall thickness or schedule), quantity, length, end finish and inspection requirements including any ferrite content limits or third-party witnessing.

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