ASTM A789 seamless and welded tube is a standard specification for general-service duplex stainless steel tubes, covering both seamless and welded construction. These tubes are intended for applications requiring high strength, excellent corrosion resistance, and reliability in aggressive environments.
ASTM A789 tubes are available in a range of duplex grades, including standard duplex 2205, super duplex 2507, lean duplex, and other specialty grades. They are widely used in heat exchangers, condensers, instrumentation lines, hydraulic systems, and process piping across oil & gas, chemical processing, marine, and desalination industries.
Key Features
| Feature |
Description |
| Standard |
ASTM A789 / ASME SA789 |
| Construction Types |
Seamless and welded (longitudinally welded) |
| Available Grades |
2205, 2507, 2304, S31803, S32205, S32750, S32760 |
| Microstructure |
Austenitic + Ferritic (dual-phase) |
| Yield Strength |
400 – 550 MPa depending on grade |
| PREN |
25 – 42 depending on grade |
| Corrosion Resistance |
Excellent against SCC, pitting, and crevice corrosion |
| Temperature Range |
Up to 600°F (316°C) continuous service |
Available Grades
| Grade |
UNS |
Type |
Yield Strength (min) |
PREN |
Key Application |
| 2304 |
S32304 |
Lean Duplex |
≥400 MPa |
~25 |
Cost-effective alternative to 304/316 |
| 2205 |
S32205 / S31803 |
Standard Duplex |
≥450 MPa |
≥35 |
Most widely used: heat exchangers, process lines |
| 2507 |
S32750 |
Super Duplex |
≥550 MPa |
≥42 |
Extreme environments; subsea, high chloride |
| S32760 |
S32760 |
Super Duplex (Z100) |
≥550 MPa |
≥40 |
Offshore, seawater, sour service |
Equivalent Designations
| Grade |
ASTM UNS |
EN |
JIS |
| 2304 |
S32304 |
1.4362 |
SUS329J3L |
| 2205 |
S32205 / S31803 |
1.4462 |
SUS329J3L |
| 2507 |
S32750 |
1.4410 |
SUS329J4L |
| S32760 |
S32760 |
1.4501 |
— |
Specifications & Size Range
| Parameter |
Seamless Tube |
Welded Tube |
| Outer Diameter (OD) |
6.0 mm – 219.1 mm |
6.0 mm – 219.1 mm |
| Wall Thickness (WT) |
0.5 mm – 15 mm |
0.5 mm – 8 mm |
| Length |
6.0 m random; custom lengths available |
6.0 m random; custom lengths available |
| Manufacturing Process |
Cold-drawn seamless |
longitudinally welded (automatic GTAW) |
| Surface Condition |
Pickled, annealed, polished |
Pickled, annealed, polished |
Seamless vs. Welded Tube Comparison
| Feature |
Seamless Tube |
Welded Tube |
| Construction |
No weld seam |
Longitudinal weld |
| Pressure Rating |
Higher |
Slightly lower |
| Cost |
Higher |
Lower (10-20% less) |
| Lead Time |
Longer |
Shorter |
| Size Availability |
Limited in large diameters |
More flexible |
| Weld Integrity |
N/A |
100% NDT tested |
| Best For |
High pressure, sour service, critical applications |
General service, heat exchangers, cost-sensitive projects |
Corrosion Resistance Highlights
| Corrosion Type |
2205 Performance |
2507 Performance |
| Pitting / Crevice |
Excellent (PREN ≥35) |
Very High (PREN ≥42) |
| Stress Corrosion Cracking |
Highly resistant |
Very highly resistant |
| General Corrosion |
Superior to 316L |
Superior to 2205 |
| Seawater Resistance |
Good |
Excellent |
| H₂S Sour Service |
NACE MR0175 compliant |
NACE MR0175 compliant |
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