HAOMEI Aluminum CO., LTD.
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Duplex Seamless Pipe
Duplex seamless pipe is designed for demanding environments where both high strength and excellent corrosion resistance are required. Compared with conventional austenitic stainless steel pipe, duplex stainless steel offers improved resistance to pitting corrosion, crevice corrosion and chloride stress corrosion cracking, making it a reliable choice for marine, offshore, seawater and pressure piping systems.
We supply high quality duplex stainless steel seamless pipe in commonly used grades such as duplex 2205 (UNS S31803 / S32205) and super duplex 2507 (UNS S32750) according to ASTM SA789, ASTM SA789M, ASTM SA790, EN 10216-5 etc.. Our products can be supplied in accordance with international standards, with full material traceability, inspection reports and project-specific documentation upon request.
What Is Duplex Seamless Pipe?
Duplex stainless steel seamless pipe combines the advantages of ferritic and austenitic stainless steels. It offers higher strength than standard stainless grades such as 304L and 316L, while providing better resistance to chloride-containing environments. This makes duplex seamless products a reliable choice for marine piping, offshore systems, seawater cooling lines, heat exchangers, pressure equipment and corrosive process applications.
For different project requirements, duplex seamless pipe products may be supplied under different standards. In general:
ASTM A790 is commonly used for duplex stainless steel pipe
ASTM A789 is commonly used for duplex stainless steel tube, including heat exchanger and general service tubing
EN 10216-5 is used for seamless stainless steel tubes for pressure purposes
Depending on your order specification, we can support EN 10204 3.1, PMI, hydrostatic testing, UT / ET inspection, and third-party inspection.
Specification of Duplex Stainless Steel Seamless Pipe:
Item | Description |
Product Name | Duplex Stainless Steel Seamless Pipe |
Material Grades | UNS S31803 / S32205 (2205), UNS S32750 (2507) |
Standards | ASTM A790, ASTM A789, ASTM A928, EN 10216-5 |
Outside Diameter | 6 mm – 610 mm |
Wall Thickness | 1 mm – 40 mm |
Length | Random Length / Fixed Length / Customized |
Surface Finish | Annealed, Pickled |
Pipe Ends | Plain End / Beveled End |
Marking | Standard Marking / Customized Marking |
Certification | EN 10204 3.1, 3.2 upon request |
Inspection | PMI, Hydrotest, UT, ET, Dimensional Inspection |
Applications | Marine, Offshore, Seawater, Heat Exchangers, Chemical Process |
Note: ASTM A790 is typically used for pipe, while ASTM A789 is generally used for tube applications. Supply scope should be confirmed according to the actual project requirement.
Grades of Duplex Stainless Steel Seamless Pipe:
UNS S31803 / UNS S32205
2205 is one of the most widely used duplex stainless steel grades. It offers a balanced combination of strength, corrosion resistance and fabrication performance. It is commonly used in marine systems, seawater lines, offshore piping and industrial process equipment.
Typical advantages of 2205:
- Higher strength than 304L and 316L
- Good resistance to pitting and crevice corrosion
- Improved resistance to chloride stress corrosion cracking
- Suitable for marine and industrial corrosive environments
UNS S32750
2507 is a super duplex stainless steel grade intended for more severe service conditions. It provides higher strength and corrosion resistance than 2205, especially in aggressive chloride and seawater environments.
Typical advantages of 2507:
- Excellent corrosion resistance in aggressive chloride environments
- Higher PREN value
- Very high mechanical strength
- Suitable for offshore, seawater and critical process systems
Chemical composition of 2205 and 2507 Duplex Stainless Steel:
Grade | Element | C | Cr | Ni | Mo | N | Mn | Si | P | S |
2205 | Typical Range (%) | ≤ 0.03 | 22.0 – 23.0 | 4.5 – 6.5 | 3.0 – 3.5 | 0.14 – 0.20 | ≤ 2.0 | ≤ 1.0 | ≤ 0.03 | ≤ 0.02 |
2507 | ≤ 0.03 | 24.0 – 26.0 | 6.0 – 8.0 | 3.0 – 5.0 | 0.24 – 0.32 | ≤ 1.2 | ≤ 0.8 | ≤ 0.035 | ≤ 0.02 |
Physical properties of 2205 and 2507 Duplex Stainless Steel:
Grade | Tensile Strength | Yield Strength | Elongation |
2205 | ≥ 620 MPa | ≥ 450 MPa | ≥ 25% |
2507 | ≥ 800 MPa | ≥ 550 MPa | ≥ 15% |
Standards of Duplex Stainless Steel Seamless Pipe:
Our duplex stainless steel seamless products can be supplied according to the following standards:
ASTM A790 – Standard Specification for Seamless and Welded Ferritic/Austenitic Stainless Steel Pipe
ASTM A789 – Standard Specification for Seamless and Welded Ferritic/Austenitic Stainless Steel Tubing for General Service
ASTM A928 – Ferritic/austenitic stainless steel tubing
EN 10216-5 – Seamless stainless steel tubes for pressure purposes
How to choose the standards?
Choose ASTM A790 for duplex stainless steel pipe applications
Choose ASTM A789 for duplex stainless steel tubing and heat exchanger applications
Choose EN 10216-5 when European pressure tube standards are required
Advantages of Duplex Stainless Steel Seamless Pipe:
Duplex seamless pipe is widely selected in demanding industrial and marine projects because of its combined mechanical and corrosion performance.
High Strength
Duplex stainless steel has higher yield strength than conventional austenitic stainless steel, which may help optimize wall thickness in some systems.
Good Resistance to Pitting and Crevice Corrosion
Suitable for chloride-containing media and marine environments.
Improved Resistance to Chloride Stress Corrosion Cracking
A major advantage in offshore, seawater and chemical service.
Suitable for Marine and Offshore Use
Commonly used in shipbuilding, seawater piping and offshore equipment.
Available in Pipe and Tube Standards
Supply can be arranged according to ASTM A790 for pipe applications and ASTM A789 for tubing applications.
Seamless Construction
Suitable for applications requiring reliable pressure performance and uniform structure.
Traceability and Documentation Support
Full identification and inspection documents are available upon request.
What We Offer?
We can supply duplex seamless pipe and tube in a wide range of dimensions for industrial and project applications.
Outside Diameter: 1/8” to 24”
Wall Thickness: SCH 5S to SCH XXS or specified wall thickness
Length: 5.8m, 6m, random length or customized
Ends: Plain end, beveled end
Surface: Pickled, annealed
Packing: Bundled, wooden cases, export seaworthy packing
Supply capability for 2205 and 2507 duplex stainless steel
Support for ASTM A790, ASTM A789 and EN 10216-5
Suitable for both pipe and tube project requirements
Inspection and certification support available
Full traceability and export documentation
Technical response for marine, offshore and industrial applications
Fast quotation support
For accurate quotation, please provide:
Grade
Standard
Pipe or tube requirement
OD × WT or NPS × SCH
Length
Quantity
Certificate requirement
Applications of Duplex Stainless Steel Seamless Pipe:
Duplex seamless pipe and tube are widely used in systems where corrosion resistance and strength are both important.
Marine piping systems
Seawater cooling systems
Ballast water lines
Offshore platform piping
Shipbuilding and ship repair projects
Heat exchangers
General service tubing
Pressure piping systems
Desalination plants
Chemical processing lines
Oil and gas service applications
Quality Check of Duplex Stainless Steel Seamless Pipe:
To meet project and export requirements, we can provide inspection and documentation according to the order specification.
Positive Material Identification (PMI)
Hydrostatic Testing
Eddy Current Testing (ET)
Ultrasonic Testing (UT)
Dimensional Inspection
Surface Inspection
Chemical Composition Verification
Mechanical Property Testing
EN 10204 3.1 Mill Test Certificate
EN 10204 3.2 upon request
Heat number traceability
Inspection reports
Packing list and marking details
Third-party inspection reports upon request
Inspection can be arranged by:
SGS
TÜV
BV
DNV (subject to order/project arrangement)
Other nominated agencies
Package of Duplex Stainless Steel Seamless Pipe:
Our duplex seamless pipe is packed for export shipment and traceable storage.
Bundled packing for standard sizes
Wooden cases for small-size tubes or special requirements
Plastic end caps when required
Waterproof export wrapping
Marking with heat number and specification
FAQ:
Duplex Stainless Steel Seamless Pipe is a pipe manufactured without a welded seam and made from duplex stainless steel grades such as 2205 or 2507. It combines high strength with excellent corrosion resistance, making it suitable for marine, offshore, chemical processing, and other demanding application.
The most common grades are Duplex 2205 (UNS S31803 / S32205) and Super Duplex 2507 (UNS S32750).
2205 is widely used for general industrial and marine service, while 2507 is preferred for more aggressive chloride and seawater environments.
Duplex 2205 offers a good balance of strength, corrosion resistance, and cost for many applications.
Super Duplex 2507 provides higher resistance to pitting, crevice corrosion, and chloride attack, making it more suitable for severe offshore and seawater service conditions.
Common standards include ASTM A790 for duplex stainless steel pipe and ASTM A789 for duplex stainless steel tubing.
Specific standards may vary depending on the project, pressure rating, and application requirements.
Yes. Duplex Stainless Steel Seamless Pipe is widely used in seawater systems because of its excellent resistance to chloride corrosion.
For more demanding marine conditions, super duplex grades such as 2507 are often recommended.
Its main advantages include high mechanical strength, excellent resistance to pitting and crevice corrosion, improved resistance to chloride stress corrosion cracking, and long service life in harsh environments.
Common documents include EN 10204 3.1 Mill Test Certificate, chemical composition report, mechanical property report, PMI report, and other inspection documents according to customer or project requirements.
Typical tests include chemical analysis, mechanical testing, hydrostatic testing, PMI, dimensional inspection, surface inspection, and other non-destructive tests if required.
It is commonly used in marine piping systems, offshore platforms, seawater cooling systems, desalination plants, heat exchangers, chemical processing, oil and gas, and other corrosion-sensitive environments.
For an accurate quotation, please provide the grade, standard, size, wall thickness, length, quantity, application, certificate requirements, and destination port.
