ASTM A249/A249M – standard specification for welded Austenitic steel boiler, super heater, Heat-Exchanger, and condenser tubes, this specification covers stainless steel nominal wall-thickness and heavily cold worked welded tube intended for heat exchanger and other high temperature service.
Seeing specific details, download ASTM A249 specification in PDF, equivalent standard is ASME SA249.
ASTM A249 specifies a series of requirements may include, such as grade, size, manufacture, testing and special requirements, users can specify requirements that not listed in this specification, like stainless steel material, in practice, Ferritic steels are often required, like TP439, TP409L.
Stainless Steel Grades
Welded tubes made from the Austenitic steels with various grades, the majority of grades are so called 300 series, these grades have high strength and excellent corrosion resistance for critical applications.
Table 1, common grades and chemical composition
|TP304||0,08||1,0||2||18 – 20||8 – 11||–||0,03||0,045|
|TP304L||0,030||1,0||2||18 – 20||8 – 12||–||0,03||0,045|
|TP316||0,08||1,0||2||16 – 18||10 – 14||2 – 3||0,03||0,045|
|TP316L||0,030||1,0||2||16 – 18||10 – 14||2 – 3||0,03||0,045|
|TP321||0,08||1,0||2||17 – 19||9 – 12||–||0,03||0,045|
TP321 has other alloys to be added, Nitrogen 0.10, Ti 5(C+N)-0.70.
Table 2, mechanical properties and solution temperature (Min, degree centigrade).
|Grade||Tensile strength(Mpa)||Yield point(Mpa)||Elongation(%)||Hardness(HRB)||Solution temperature|
The tubing sizes and thicknesses usually furnished to this specification are 1/. inch [3.2 mm] in inside diameter to 12 inch [304.8 mm] in outside diameter and 0.015 to 0.320 in. [0.4 to 8.1 mm]
Outside diameter ranges from 6.35 to 101.6 mm, wall thickness ranges from 0.51 to 3.05 mm, these sizes are common for heat exchanger tube, average wall and minimum wall are available upon request.
Dimensional tolerances other than wall thickness tolerances shall be in accordance with Specification A 1016/A 1016M. Wall thickness tolerances shall be 10 % of nominal wall for all tubing sizes.
Table 3, outside diameter, wall thickness, length tolerance
|＜25.40mm||±0.10mm||±10.00%||OD＜50.8mm +3.0mm -0mm
OD≥50.8mm +5.0 -0mm
The welded (WLD) tubes shall be made from flat-rolled steel by an automatic welding process with no addition of filler metal, generally, made from strip, coil, plate, subsequent to welding and prior to final heat treatment, the tubes shall be cold worked either in both weld and base metal or in weld metal only.
The tubes, after final heat treatment, shall be chemically descaled or pickled free of scale. When bright annealing is used, pickling or chemical descaling is not necessary.
Testing and inspection:
- Reverse-Bend Test
- Tension Test
- Flattening Test
- Flange Test
- Hardness Test—Brinell or Rockwell hardness tests
- Hydrostatic or Nondestructive Electric Test (eddy current test)
- Grain Size
- Air Underwater Pressure Test (option)
- Intergranular Corrosion Test (option)
- Weld Decay Test (option)