ASTM A790/A790M — Seamless and welded duplex stainless steel pipes (enhanced version)
Grades
S31803, S32205, S32304, S32550, S32750, S32760, S32900, S32950
Chemical composition and mechanical properties
| Grade | Chemical composition | Mechanical properties |
|---|---|---|
| S31803 | C≤0.030, Mn≤2.00, Si≤1.00, P≤0.030, S≤0.020, N 0.08-0.20, Cr 21.00-23.00, Ni 4.50-6.50, Mo 2.50-3.50 | Rm ≥620 MPa, Rp0.2 ≥450 MPa, A≥25%, HB≤293, similar to biphase 2205. |
| S32205 | C≤0.030, Mn≤2.00, Si≤1.00, P≤0.030, S≤0.020, N 0.14-0.20, Cr 22.00-23.00, Ni 4.50-6.50, Mo 3.00-3.50 | Rm ≥655 MPa, Rp0.2 ≥485 MPa, A≥25%, HB≤293, biphase 2205 |
| S32304 | C≤0.030, Mn≤2.00, Si≤1.00, P≤0.040, S≤0.030, N 0.10-0.20, Cr 21.50-24.50, Ni 3.00-5.50, Mo 0.05-0.60, Cu 0.05-0.60 | Rm ≥600 MPa, Rp0.2 ≥400 MPa, A≥25%, HB≤293, biphase 2304 |
Application scope
ASTM A790/A790M specifications define seamless and welded duplex stainless steel pipes for corrosive environments. Inspection and corrosion resistance requirements are more stringent than general-purpose standards, and delivery is in the solution-annealed state. Duplex grades combine high strength with excellent resistance to pitting, crevice corrosion, and stress corrosion cracking, covering a range from economical to super duplex varieties. They are suitable for pressure pipelines operating in highly corrosive media with high reliability requirements.
Typical applications
Widely used in oil and gas industry gathering and transportation pipelines and process pipelines, chemical equipment corrosion-resistant pipelines, and highly corrosive environments such as seawater treatment, flue gas desulfurization, and papermaking. Its stricter acceptance standards compared to general standards make it suitable for transporting media with high safety requirements. With its high strength and resistance to chloride ion corrosion, it is used as corrosion-resistant main pipes, heat exchange pipes, and equipment connections, serving harsh corrosive environments for long-term reliable operation.
