ASTM A423/A423M

ASTM A423/A423M Standard Specification for Seamless and Electric-Welded Low-Alloy Steel Tubes.

ASTM A423 specification covers standards for minimum-wall-thickness, seamless, and electric-resistance welded low-alloy steel tubes to be used for pressure containing parts, that is economizers, and for other corrosion resistant applications. Steel tubes shall either be processed to hot or cold finish. All tubes shall be normalized or given such heat treatment as may be necessary to conform to the requirements of this specification. Chemical composition shall adhere to specified carbon, manganese, phosphorus, sulfur, silicon, copper, chromium, nickel, and molybdenum contents. Tension, flattening, flaring, flange, hardness, reverse flattening, and hydrostatic tests shall be performed. Tubes when inserted in the boiler shall stand expanding and bending without showing cracks or flaws. Tubes shall also conform to tensile strength, yield strength, hardness, and elongation requirements.


1.1 This specification2 covers minimum-wall-thickness, low-alloy steel tubes for pressure containing parts such as economizers or other applications where corrosion resistance is important.

1.2 The tubing sizes and thicknesses usually furnished to this specification are 1/2 to 5 in. [12.7 to 127 mm] in outside diameter and 0.035 to 0.500 in. [0.9 to 12.7 mm] inclusive, in minimum wall thickness. Tubing having other dimensions may be furnished, provided such tubes comply with all other requirements of this specification.

1.3 Mechanical property requirements do not apply to tubing smaller than 1/4 in. [3.2 mm] in inside diameter or 0.015 in. [0.4 mm] in thickness.

1.4 This specification covers three grades, two types, and two manufacture finishes:

1.4.1 Grades 1, 2, and 3 are identified in Table 1 (Chemical Requirements), and Table 3 (Tensile Requirements),

1.4.2 Type (seamless or electric-resistance welded),

1.4.3 Manufacture (hot finished or cold finished).

1.5 Optional supplementary requirements S1 and S2 are provided and, when desired, shall be so stated in the order.

1.6 The values stated in either SI units or inch-pound units are to be regarded separately as standard. Within the text, the SI units are shown in brackets. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard. The inch-pound units shall apply unless the “M” designation of this specification is specified in the order.

1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

Chemistry Composition

Grade C, % Mn, % P, % S, % Si, % Cu, % Cr, % Ni, % Mo, % Sb, %
ASTM A423 Gr.3 0.06 max 0.70-1.40 0.020 max 0.020 max 0.55 max 0.25-0.45 - 0.50 max 0.20 max 0.05-0.15
S-TEN1 0.14 max 1.60 max 0.025 max 0.025 max 0.55 max 0.25-0.50 - 0.50 max - 0.15 max
09CrCuSb 0.12 max 0.35-0.65 0.030 max 0.020 max 0.17-0.37 0.25-0.45 0.70-1.10 - - 0.04-0.10

Mechanical Properties

Grade Tensile Strength, Mpa Yield Strength, Mpa Elongation, %
ASTM A423 Gr.3 380 min 230 min 35 min
S-TEN1 380 min 230 min 35 min
09CrCuSb 390-550 245 min 30 min

Outside Diameter & Tolerance

Outside Diameter, mm Tolerance, mm
3.2≤OD<25.4 ±0.10
25.4≤OD≤38.1 ±0.15
38.1<OD<50.8 ±0.20
50.8≤OD<63.5 ±0.25
63.5≤OD<76.2 ±0.30
76.2 ±0.38


Steel 09CrCuSb 1Cr18Ni9 Corten S-TEN1
Corrision Speed 7.3 21.7 63 27.4
Times 1 2.97 8.63 3.75

Wall thickness & Tolerance

Outside Diamter, mm Tolerance, %
3.2≤OD<38.1 +20/-0
38.1≤OD≤76.2 +22/-0

Length: 6050mm; 6096mm; 7315mm; 11800mm; 12000mm; and so on.
Max developed length: 30 meters, also U bending can be offered.

Popular Dimensions

OD (mm) WT (mm) Length (mm) OD (mm) WT (mm) Length (mm)
76.2 3.0 3000 60.3 3.0 3000
60.3 3.0 4800 60.3 3.0 3000


Mechanical Tests Required

Tension Test—One tension test will be made on a specimen for lots of not more than 50 tubes.
Flattening Test—One flattening test will be made on specimens from each end ofone finished tube, not the one used for the flaring or flanging test, from each lot .
Flange Test (ASTM A423 Grade 1 Welded Steel Tubes)—One flange test shall be made on specimens from each end of one finished tube, not the one used for the flattening test, from each lot.
Hardness Test—Brinell or Rockwell hardness tests will be made on specimens from two tubes from each lot
Reverse Flattening Test—For welded tubes, one reverse flattening test shall be made on a specimen from each 1500 ft [460 m] of finished tubing.
Hydrostatic or Nondestructive Electric Test—Each tube will be subjected to the hydrostatic test.

General Requirements

All tubes shall be supplied as per applicable ASTM B338 /B338M, ASTM A450/A450M Specification
Mill test certificates will be issued
We can provide 3.2 Certification according to the needs of you

Product Marking

In addition to the marking prescribed in Specification A450/A450M, the marking shall include whether hot finished or cold finished, and whether seamless or welded.

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