ASTM A790 vs. ASTM A789: Key Differences
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What is ASTM A790 material?
ASTM A790 is a standard specification for seamless and welded ferritic/austenitic (duplex) stainless steel pipes, designed for high-strength, corrosive service, particularly where chloride stress corrosion cracking is a concern. It covers materials with a mixed microstructure of ~50% austenite and ~50% ferrite, offering double the strength of standard 304/316 steels.
What is A789 tube material?
ASTM A789 specification for tubing covers seamless and welded ferritic/austenitic (duplex) stainless steels, representing a standard for stainless steel materials that combines both high strength and corrosion resistance. This material is primarily utilized in service environments where exceptional resistance to chloride stress corrosion cracking is required ,such as in heat exchangers, condensers, and associated equipment within the oil and gas or chemical processing industries.
ASTM A790 vs. ASTM A789: Key Differences
| Standard Item |
ASTM A789 | ASTM A790 | EN 10216-5 |
| Mainly Grade | S31803 S32205 S32750 | S31803 S32205 S32750 | 1.4301 1.4307 1.4948 1.4315 1.4401 1.4404 1.4571 1.4541 1.4941 1.4845 1.4449 1.4438 1.4550 1.4912 1.4462 1.4410 |
| Yield Strength (Mpa) |
≥450;≥485;≥550 | ≥450;≥450;≥550 | - |
| Tensile Strength (Mpa) |
≥620;≥655;≥800 | ≥620;≥655;≥800 | - |
| Elongation(%) | ≥25;≥25;≥15 | ≥25;≥25;≥15 | - |
| Hydrostatic Test | The Hydrostatic Test shall be in accordance with ASTM A1016.Could be replaced by ECT. | The Hydrostatic Test shall be in accordance with ASTM A999.Could be replaced by ECT. | The hydrostatic test shall be carried out at a test pressure of 7MPa or at a test pressure calculated using the following formula P=2St/D S=70%Rp0.2 |
| Intergranular Corrosion Test | Usually use Pitting Corrosion Test. | Usually use Pitting Corrosion Test. | EN ISO 3651-2 (Optional) |
| Eddy Current Test | Could be replaced by HT. | Could be replaced by HT. | EN 10246-3 |
ASTM A790 vs. ASTM A789 ：Dimensional Tolerances
| Parameter | ASTM A790 (Pipe) | ASTM A789 (Tube) |
|---|---|---|
| Outside Diameter (OD) | ±0.75% of OD | ±0.10 mm (OD ≤ 38 mm) ±0.25% of OD (OD > 38 mm) |
| Wall Thickness (WT) | -12.5% / +Not specified (typically +20% allowed) | ±10% of nominal wall thickness |
| Length Tolerance | -0 / +6 mm (for random lengths) Cut lengths: ±3 mm |
Cut lengths: ±3 mm U-tubes: tighter control per agreement |
| Straightness | Max 0.2% of length | Typically tighter than pipe (e.g., ≤ 1/1000 of length) |
| Ovality (Out-of-Roundness) | Included within OD tolerance | Limited to OD tolerance; stricter control |
| End Squareness (Cutting Angle) | Not explicitly strict | Ends shall be reasonably square (stricter for heat exchanger use) |
ASTM A790 vs. ASTM A789 Duplex Tubing: Applications
ASTM A790 and ASTM A789 are both duplex stainless steel standards offering high strength and corrosion resistance, but they serve different primary purposes. ASTM A790 covers pipe for general corrosive service and piping systems, while ASTM A789 covers tubing for heat exchangers and boiler services, typically featuring smaller outer diameters.
What is the difference between ASTM A790 and ASTM A928?
ASTM A790 and ASTM A928 are both standards for ferritic-austenitic (duplex) stainless steel pipes designed for corrosive environments, but they differ primarily in manufacturing method and welding. ASTM A790 covers seamless and welded pipes (usually without filler metal), while ASTM A928 covers only electric-fusion-welded (EFW) pipes, typically manufactured with filler metal, suitable for larger diameters.
ASTM A789 ASTM A790 Cold Drawn/Rolled Stainless Steel Tubes Supplier
Material Grades & Standards
| Product Type | Standard Specification | Common Material Grades (UNS) | Equivalent Grade |
| Duplex Steel Tube | ASTM A789 / ASME SA789 | S31803, S32205, S2205 | 1.4462 |
| Duplex Steel Pipe | ASTM A790 / ASME SA790 | S31803, S32205, S2205 | 1.4462 |
| Super Duplex Steel | ASTM A789 / A790 | S32750, S32760 | 1.4410, 1.4501 |
| Austenitic Steel | ASTM A213 / A312 | TP304/L, TP316/L, TP317L, TP347/H | 1.4301, 1.4404 |
Dimensional Range (Cold Drawn / Cold Rolled)
| Manufacturing Process | Outside Diameter (OD) | Wall Thickness (WT) | Maximum Length |
| Cold Drawn (CD) | 6.0 mm – 219.1 mm | 0.5 mm – 20.0 mm | Up to 25 Meters |
| Cold Rolled (CR) | 10.0 mm – 114.3 mm | 0.5 mm – 10.0 mm | Up to 18 Meters |
| U-Bend Tubes | Per Customer Drawing | Per Customer Drawing | Developed Length Max 30m |
Packaging and Payment Terms
Payment Terms:
T/T (Telegraphic Transfer), L/C, Western Union, PayPal
Minimum Order Quantity: 1 ton (negotiable for large projects)
Delivery Time: Typically 7–15 days after order confirmation, depending on location and size of the order.
Packaging:
All ASTM A789 / A790 tubes are carefully packaged to avoid any damage during transit. Options include:
Wooden Boxes or Pallets with moisture protection
Shrink-Wrap or Bubble Wrap for smaller quantities
