ASTM A213 UNS S32100 / TP321 Stainless Steel Tube EN 1.4541 Heat Exchanger Tube
ASTM A213 TP321 / UNS S32100 Stainless Steel Seamless Tube Heat Exchanger Tube
ASTM A213/ASME SA213 defines seamless austenitic stainless-steel tubes for boilers, superheaters, and heat exchangers. Grade TP321 (UNS S32100), equivalent to EN 1.4541, is the titanium-stabilized variant of Type 304. The titanium addition (≥5×(C+N)) prevents sensitization by forming stable titanium carbides, eliminating chromium depletion at grain boundaries. This provides outstanding resistance to intergranular corrosion, especially during welding or service within 425°C–815°C. These tubes offer high creep strength and oxidation resistance up to ~900°C. Supplied solution-annealed, they meet 515 MPa minimum tensile strength. They are used in refinery heaters, chemical processing, and power-generation exchangers requiring high-temperature stability.
Equivalent Grade of ASTM A213 UNS S32100 / TP304 / EN 1.4541 Stainless Steel Seamless Tube
| STANDARD | WERKSTOFF NR. | UNS | JIS | EN |
| SS 321 | 1.4541 | S32100 | SUS 321 | X6CrNiTi18-10 |
Chemical Composition (%) of ASTM A213 UNS S32100 / TP304 / EN 1.4541 Stainless Steel Seamless Tube
| C | Mn | P | S | Si | Cr | Ni | Ti |
| 0.08 | 2.00 | 0.045 | 0.03 | 1.00 | 17.0-19.0 | 9.0-12.0 | 5(C+N)-0.7 |
Mechanical Properties of ASTM A213 UNS S32100 / TP304 / EN 1.4541 Stainless Steel Seamless Tube
| Tensile Strength min. | Yield Strength min. | Elongation (%) | Hardness max | |
| 75ksi (515MPa) | 30ksi (205MPa) | 35min | 192HBW/200HV | 90 HRB |
Specific Requirements for Heat Exchanger Tubes
Under ASTM A213, tubes intended for heat exchangers must meet strict non-destructive testing (NDT) requirements:
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Dimensions: Outside diameter (OD) ranges typically from 1/8" to 5" (3.2mm to 127mm), with minimum wall thicknesses.
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Flattening Test & Flaring Test: Required to prove ductility for tube rolling into tube sheets.
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Hydrostatic Test or NDT: Each tube must pass either a hydrostatic pressure test (without leakage) or an eddy-current / ultrasonic test (per ASME Section V).
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Surface Finish: Must be free of scale, pits, and cracks. Internal bore cleanliness is critical for heat transfer efficiency.
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Refinery Crude Heaters: Especially where sulfur-containing fuels are burned (prevents polythionic acid stress corrosion cracking).
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Chemical Process Industries: Handling organic and inorganic chemicals (excluding highly oxidizing acids like hot concentrated nitric acid at certain concentrations).
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Power Generation: Superheaters and reheaters requiring high creep resistance.
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Aerospace and Petrochemical: High-temperature fluid-to-air or fluid-to-fluid cooling/heating coils.
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