What Is a Seamless Stainless Steel TP321 Tube?
TP321 Seamless Stainless Steel Tube is supplied for titanium stabilization for intergranular-corrosion resistance after heating. The size range shown (OD 6–257 mm; WT 0.5–35 mm) is the overall capability across this product family, not a per-grade commitment. Confirm the specific OD × WT × length combination for the ordered grade in the quotation. The governing specification must be stated on the purchase order: ASTM A269 or ASTM A213 / ASME SA213, subject to service. Chemistry, mechanical properties, heat treatment, dimensional tolerance, NDT and certification must be reported against the ordered standard and material heat; do not treat typical values as guaranteed acceptance limits.
Unlike welded tubes, TP321 seamless tubes are manufactured from a solid billet through extrusion or cold drawing, ensuring:
- No longitudinal weld seam
- Superior pressure resistance
- Uniform microstructure and wall thickness
The addition of titanium (Ti) stabilizes the material by binding carbon, limiting chromium carbide precipitation within the temperature range of 425°C–816°C (800°F–1500°F). This provides excellent resistance to intergranular corrosion, especially after welding or prolonged thermal exposure.
Compared to TP304 / TP304L stainless steel tubes, TP321 offers significantly better performance in high-temperature cyclic environments.
Key Features and Competitive Advantages
1. Excellent Intergranular Corrosion Resistance
- Titanium stabilization (Ti ≥ 5×(C+N)) limits sensitization
- Ideal for applications involving welding and high heat
2. Superior High-Temperature Performance
- Continuous service up to 870°C (1600°F)
- Strong oxidation resistance in thermal cycling conditions
3. Seamless Structural Integrity
- Homogeneous grain structure
- Tight dimensional tolerances
- Reliable under high-pressure conditions
4. Enhanced Fabrication & Weldability
- Suitable for complex fabrication processes
- Typically does not require post-weld heat treatment
5. Cost-Effective Alternative to Nickel Alloys
- Comparable high-temperature resistance
- Lower cost compared to Inconel and other Ni-based alloys
Technical Specifications
Applicable Standards
- ASTM A213 / ASME SA213 (Seamless Tubes)
- ASTM A312 (Optional for piping systems)
- EN 10216-5 (1.4541)
- JIS G3463 / G3459
- GB/T 14976
Product Specifications and Data
To provide a comprehensive overview of this high-performance material, here are the detailed technical specifications and performance data for Seamless Stainless Steel TP321 Tube.
Equivalent Grade
| UNS | Common grade name | EN material number | EN steel name | JIS grade | GB/T grade |
|---|---|---|---|---|---|
| S32100 | 321 | 1.4541 | X6CrNiTi18-10 | SUS321 | 06Cr18Ni11Ti / 0Cr18Ni10Ti |
Grade correspondence does not make ASTM, ASME, EN, JIS and GB delivery requirements interchangeable. Confirm chemistry, heat treatment, mechanical properties, dimensions, testing and certification against the purchase specification. Approximate or unconfirmed correspondences retain their qualification. See the grade designation index.
Chemical Composition
The composition of Stainless Steel 321 is carefully balanced to achieve its superior high-temperature stability and corrosion resistance.
| C | Si | Mn | P | S | Cr | Ni | Ti |
|---|---|---|---|---|---|---|---|
| ≤0.08 | ≤1.00 | ≤2.00 | ≤0.045 | ≤0.030 | 17.00–19.00 | 9.00–12.00 | 5×(C+N)–0.70 |
Data source: ASTM A213-25 / ASME SA213 Table 1, TP321 row ≤ heat-analysis acceptance limits. Confirm the values against the ordered edition and the MTC.
Stainless Steel 321 is specifically designed to maintain its strength and shape in high-temperature, high-stress environments.
| Tensile Strength | Yield Strength | Elongation | Hardness |
|---|---|---|---|
| ≥ 515 MPa | ≥ 205 MPa | ≥ 35% | ≤ 192 HBW / 200 HV / 90 HRB |
Typical Physical Properties
These physical properties highlight the material’s ability to perform reliably under a wide range of conditions.
| Density | Melting Point | Thermal Expansion | Thermal Conductivity | Modulus of Elasticity | Electrical Resistivity |
|---|---|---|---|---|---|
| 8.0 g/cm³ | 1398 -1454 °C | 16.6 μm/m·°C (20-100°C) | 16.3 W/m·K (20°C) | 193 GPa | 0.72 x 10⁻⁶ Ω·m (20°C) |
Note: Typical values for reference only — not acceptance limits. Physical and mechanical properties are reported on the MTC against the ordered standard, product form and condition.
ASTM A1016/A1016M Tube Size Tolerance Chart
Size Tolerance Chart (mm)
| Specified Outside Diameter (OD) (Inches) | Permissible Variations in OD (± Inches) |
|---|---|
| 1⁄2 to 1 | ±0.005 |
| Over 1 to 1-1⁄2 | ±0.008 |
| Over 1-1⁄2 to 2 | ±0.010 |
| Over 2 to 2-1⁄2 | ±0.012 |
| Over 2-1⁄2 to 3-1⁄2 | ±0.014 |
| Over 3-1⁄2 to 5 | ±0.020 |
Tolerance basis: permitted variations per the governing specification stated on this page and the applicable general-requirements standard (ASTM A1016 / ASME SA1016) for the ordered product form; the wall-thickness and length variations in this section follow the same basis.
| Specified Outside Diameter (OD) (Inches) | Specified Wall Thickness (WT) (Inches) | Permissible Variation (± Inches) |
|---|---|---|
| 1⁄2 to 1 (Inclusive) | 0.025 to 0.065(Inclusive) | ±0.010 |
| Over 0.065to 0.134 (Inclusive) | ±0.012 | |
| Over 1 to 1-1⁄2 (Inclusive) | 0.025 to 0.065 (Inclusive) | ±0.010 |
| Over 0.065 to 0.134 (Inclusive) | ±0.012 | |
| Over 1-1⁄2 to 2 (Inclusive) | 0.025 to 0.049 (Inclusive) | ±0.011 |
| Over 0.049 to 0.083 (Inclusive) | ±0.012 | |
| Over 0.083 to 0.148 (Inclusive) | ±0.014 | |
| Over 2 to 2-1⁄2 (Inclusive) | 0.032 to 0.065 (Inclusive) | ±0.013 |
| Over 0.065 to 0.109 (Inclusive) | ±0.015 | |
| Over 0.109 to 0.165 (Inclusive) | ±0.017 | |
| Over 2-1⁄2 to 3-1⁄2 (Inclusive) | 0.032 to 0.165 (Inclusive) | ±0.020 |
| Over 0.165 to 0.220 (Inclusive) | ±0.025 | |
| Over 3-1⁄2 to 5 (Inclusive) | 0.083 to 0.165 (Inclusive) | ±0.025 |
| Over 0.165 to 0.220 (Inclusive) | ±0.030 |
Length Tolerance
For Specific Cut Lengths, the standard tolerance is +1⁄8 in. [3 mm], -0 in. [0 mm].
Important Note: The values presented here are based on the dimensional tolerance tables in ASTM A1016/A1016M (General Requirements for Ferritic Alloy Steel, Austenitic Alloy Steel, and Stainless Steel Tubes), contains other essential requirements like straightness and details for tubes with ODs outside of this range. Always consult the latest official standard for design and procurement.
Common Industrial Applications
TP321 stainless steel tubes are widely used in high-temperature and corrosion-critical industries
Aerospace & Defense
- Jet engine exhaust systems
- Afterburners and high-heat components
Power Generation
- Superheater and reheater tubes
- High-efficiency boiler systems
Petrochemical & Refining
- Heat exchangers
- Expansion joints
- High-temperature gas pipelines
Food & Pharmaceutical Industry
- Sterilization systems
- Heat-resistant process piping
Quality Assurance & Testing
Each TP321 seamless tube undergoes strict quality control and full traceability:
Certification
- EN 10204 3.1 MTC as standard; 3.2 by arrangement
- Full raw material traceability
Non-Destructive Testing (NDT)
- Eddy Current Testing (ET) or Ultrasonic Testing (UT), as specified
- Hydrostatic Pressure Testing
Material Verification
- PMI (Positive Material Identification), when specified on the purchase order
Metallurgical Testing
- Intergranular Corrosion Test (ASTM A262 Practice E)
- Grain Size Analysis
- Flattening and Flaring Tests
Third-Party Inspection
Available on request — TÜV, SGS, Bureau Veritas (BV), Lloyd’s Register (LR)
Frequently Asked Questions
What sizes are available for TP321 seamless tube?
The overall range is OD 6–257 mm; WT 0.5–35 mm. Requirements outside this range are reviewed against mill capability on request.
Which specification governs TP321 seamless tube?
ASTM A269 or ASTM A213 / ASME SA213, subject to service is the governing specification for TP321 seamless tube. The edition in force at order time is stated on the quotation and purchase order; chemistry, mechanical properties, heat treatment, dimensions and testing are reported against the ordered standard and material heat.
What inspection documents are provided?
Each order is documented with a mill test certificate stating heat chemistry and mechanical test results. EN 10204 3.1 certification, hydrostatic testing, eddy-current or ultrasonic inspection and PMI are performed when specified in the purchase order.
Technical review: page data reviewed by the Xinzhe technical desk on 2026-09-27. Chemistry acceptance limits are compiled from the governing ASTM/ASME specification stated on this page; mechanical and physical values are typical reference data and are not acceptance guarantees. Values must be confirmed against the standard edition in force at order time and the material test certificate.
Ready to Request a Quotation?
Send the size (OD and wall or schedule), quantity, length, end finish and the inspection items you need as acceptance criteria — you will get a written quotation stating the specification and edition, delivery condition, documents included and lead time.
For the same grade in pipe form, see the TP321 seamless pipe. To compare other grades and size combinations, browse the Stainless Steel Seamless Pipe category. Minimum order quantity and lead time are confirmed on enquiry against the ordered grade, size and quantity.
