ASTM A 790 Seamless and Welded Ferritic/Austenitic Stainless Steel Pipe
This specification covers seamless and straight-seam welded ferritic/austenitic steel pipe intended for general corrosive service, with particular emphasis on resistance to stress corrosion cracking. These steels are susceptible to embrittlement if used for prolonged periods at elevated temperatures.
UNS number: S32205 (Ferritic/Austenitic steel)
Heat Treatment
Temperature: 1025-1125 °C
Quench: rapid cooling in air or water
Chemical requirements, %,
C: ≤0.030
Mn: ≤1.20
P: ≤0.035
S: ≤0.020
Si: ≤0.80
Cr: 24.0-26.0
Ni: 6.0-8.0
Mo: 3.0-5.0
N: 0.24-0.32
Cu: ≤0.50
Tensile requirements
Tensile Strength: ≥800MPa
Yield Strength.: ≥550MPa
Elongation in 2 in. or 50 mm, %: ≥15
Hardness:
HBW: ≤300
HRC: ≤32
Each tube shall be subjected to the nondestructive electric test or the hydrostatic test.
Permissible Variations in Wall Thickness
The minimum wall thickness at any point shall not be more than 12.5 % under the nominal wall thickness specified.
Permissible Variations in Outside Diameter
| NPS | Over, mm | Under, mm |
| 1⁄8 –1 1⁄2, incl | 0.4 | 0.8 |
| Over 11⁄2 to 4, incl | 0.8 | 0.8 |
| Over 4 to 8, incl | 1.6 | 0.8 |
| Over 8 to 18, incl | 2.4 | 0.8 |
| Over 18 to 26, incl | 3.2 | 0.8 |
| Over 26 to 34, incl | 4.0 | 0.8 |
| Over 34 o 48, incl | 4.8 | 0.8 |