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)

Manufacture

The pipe shall be made by the seamless or an automatic welding process, with no addition of filler metal in the welding operation.

At the manufacturer’s option, pipe may be either hot-finished or cold-finished.

The pipe shall be pickled free of scale. When bright annealing is used, pickling is not necessary.

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