Pipes of stainless steel 304 or its low-carbon version 304L may be made in accordance with ASTM A312 Grade TP304 or TP304L, respectively. The TP304 and TP304L pipes may be furnished in seamless or straight-beam (longitudinally) welded types. They are primarily intended for high-temperature and general corrosion service. TP304/ TP304L seamless pipes shall be made by a cold-drawn or hot-rolled process that does not involve welding at any stage of production, while welded pipes shall be made using an automatic welding process with no addition of filler metal during the welding process. The pipe may be furnished with plain or bevel butt welding ends, or threaded ends in accordance with ASME B1.20.1.
for TP304, %
for TP304L, %
min. MPa [ksi]
min. MPa [ksi]
2", min, % (*L)
2", min, %(*T)
Stainless steel pipes made of austenitic stainless steel ASTM A312 TP304 or TP304L shall be solution annealed. During annealing, the pipes shall be heated to the temperature no less than 1900°F [1040°C] and soak at the temperature for a period long enough so that all chromium carbides are dissolved. Since the chromium carbide dissolves slowly, the highest practical temperature consistent with limited grain growth should be selected. This temperature is in the vicinity of 1095° [2000°F]. Complete dissolution of chromium carbides reduces precipitation of intergranular carbides hence improves the resistance to intergranular corrosion. Subsequent cooling (quenching) from the annealing temperature must be fast, thus ensuring that dissolved carbides remain in solution.
|NPS||*t/D||Tolerance, % from Nominal|
ASTM A312 TP304/ TP304L seamless pipes are generally furnished in sizes 1/2″ through 24″, while ASTM A312 TP304/ TP304L welded pipes are available from 1-1/2″ through 48″. The wall thicknesses shall be furnished in accordance with ASME B36.10M or ASME B36.19M. The pipes are usually supplied in lengths of 6.096 m (20′), 12.19 m (40′), 6 m, and 12 m, etc. No pipe shall be under the specified length and no pipe shall be more than 0.25″ [6 mm] over the specified length.
Visual examination, dimensional inspection, PMI chemical analysis, tensile test, flattening test, bend test, eddy-current test, etching test, radiographic examination (for welded pipes), intergranular corrosion test (upon request).