ASTM A423 Grade 3 Low-Alloy Steel Tubes
ASTM A423 Grade 3 Steel Tubes covers minimum-wall-thickness, seamless and electric-resistance welded, low-alloy steel tubes for pressure containing parts such as economizers or other applications where corrosion resistance is important.

Description

ASTM A423 Grade 3 Low-Alloy Steel Tubes
Standard:ASTM A423/A423M
Standard Specification for Seanmless And Electric-Welded Low-Alloy Steel Tubes
ASTM A423 Grade 3 Steel Tubes covers minimum-wall-thickness, seamless and electric-resistance welded, low-alloy steel tubes for pressure containing parts such as economizers or other applications where corrosion resistance is important.
ASTM A423 Grade 3 Low-Alloy Steel Tubes 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.
Manufacture
ASTM A423 Grade 3 Low-Alloy Steel Tubes made by the seamless process may be hot finished or cold finished.
Heat Treatment
ASTM A423 Grade 3 Low-Alloy Steel Tubes shall be normalized or given such heal treatment
Chemical Composition
Carbon, max 0.06
Manganese 0.70-1.40
Phosphorus 0.020 max
Sullur. max 0.020
Silicon 0.55 max
Copper 0.25-0.45
Chromium ….
Nickel 0.50 max
Molybdenum 0.20 max
Antimony 0.05-0.15
Mechanical Properties
Grade 3
Tensile strength, min. ksi 55[380]
Yield strength, min, ksi [MPa] 33[230]
Elongation in 2 in. or 50 mm. min, % 35
For longitudinal strip tests a deduction for each 1/32 in.[0.6 mm] decrease in wall thickness below 5/16in. [8 mm] from the basic minimum elongation of the following percentage points shall be made 1.25  A
Hardness 170 HB
A  Calculated elongation requirements shall be rounded to the nearest whole number.
NOTE: 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
Forming Operations
Tubes when inserted in the boiler shall stand expanding and beading without showing cracks or flaws.
Mechanical Tests Required
Tension Test
Flattening Test
Flaring Test (Seamless Tubes)
Flange Test (Welded Tubes)
Hardness Test
Reverse Flattening Test
Hydrostatic or Nondestructive Electric Test