Stainless steel 304/ 304L seamless boiler tubes, superheater tubes, and heat-exchanger tubes shall be made of ASTM A213 Grade TP304/ TP304L steels. The tubing sizes and thicknesses usually furnished to this specification are 1/8″ in inside diameter to 5″ in outside diameter and 0.015″ to 0.500″, inclusive, in minimum wall thickness or, if specified in the order, average wall thickness. Generally, the permissible variations (tolerances) of wall thicknesses shall be controlled within ±10%.
Seamless tubes of ASTM A213 TP304/ TP304L shall be made by either a cold-drawn or a hot-rolled process. The tubes shall be solution annealed at the temperature no less than 1900°F [1040°C], followed by a quench in water or by other rapid cooling means.
|Element||TP304, %||TP304L, %|
min. MPa [ksi]
|515 ||485 |
min. MPa [ksi]
|205 ||170 |
2", min. %
The ASTM A213 TP304/ TP304L seamless tubes, when inserted in a boiler or tube sheet, shall stand expanding and beading without showing cracks or flows. When properly manipulated, the tubes shall stand all forging, welding, and bending operations necessary for application without developing defects. The tubes shall be pickled free of scale. When bright annealing is used, pickling is not necessary.
One flattening test and one flaring test shall be made on specimens from each end of one finished tube for each heat lot. Other tests and inspection include: tensile test, hardness test, eddy-current test, dimensional inspection and visual examination.