ASTM A 789 Seamless and Welded Ferritic/Austenitic Stainless Steel Tubing for General Service

This specification covers grades of average wall thickness, or, if specified on the order, minimum wall thickness, of stainless steel tubing for services requiring general corrosion resistance, 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: S32750 (Ferritic/Austenitic steel)

Ordering Information

Orders for product under this specification should in-clude the following, as required, to describe the desired material adequately:

1 Quantity (feet, metres, or number of lengths),

2 Name of product (seamless or welded tubes),

3 Grade,

4 Size (outside diameter and average wall thickness, unless minimum wall thickness is specified),

5 Length (specific or random),

6 Optional requirements,

7 Test report required (see the Inspection section of Specification A1016/A1016M),

8 Specification designation, and

9 Special requirements.

Manufacture

The tubes shall be made by the seamless or welded process with no filler metal added.

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 Dimensions