What Is a Seamless Stainless Steel TP321H Tube?
TP321H Seamless Stainless Steel Tube is supplied for titanium stabilization with higher carbon for high-temperature strength. 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 A213 / ASME SA213. 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.
Manufactured through a seamless process (hot piercing + precision cold finishing), it provides:
- Uniform microstructure
- No longitudinal weld seam
- Excellent high-pressure integrity
- Superior resistance to thermal cycling
- Carbon content: 0.04% – 0.10% (controlled high carbon)
- Titanium (Ti) stabilized
Titanium binds with carbon to form TiC (titanium carbides), preventing:
- Chromium carbide precipitation
- Intergranular corrosion (IGC)
- Sensitization during welding and heat exposure
Ideal for service temperatures in the range of:
427°C – 816°C (800°F – 1500°F)
2. Key Features & Technical Advantages
Superior Creep & Stress Rupture Strength
- Higher carbon content improves high-temperature mechanical stability
- Excellent resistance to long-term stress and deformation
Titanium Stabilization (IGC Resistance)
- Prevents sensitization in the carbide precipitation temperature range
- Excellent resistance to intergranular corrosion (IGC)
- No post-weld heat treatment required
High-Temperature Oxidation Resistance
- Comparable oxidation resistance to TP304/304L
- Stable scaling resistance up to ~816°C continuous service
High Pressure & Structural Integrity
- No longitudinal weld seam
Excellent Fabricability
- Good ductility and toughness
- Easily welded and cold formed
- Suitable for complex fabrication requirements
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 TP321H Tube.
Equivalent Grade
| UNS | Common grade name | EN material number | EN steel name | JIS grade | GB/T grade |
|---|---|---|---|---|---|
| S32109 | 321H | 1.4940 (approx.) | X7CrNiTi18-10 | SUS321HTB (product suffix to verify) | 07Cr19Ni11Ti |
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 321H is carefully balanced to achieve its superior high-temperature strength and corrosion resistance.
| C | Si | Mn | P | S | Cr | Ni | Ti |
|---|---|---|---|---|---|---|---|
| 0.04–0.10 | ≤1.00 | ≤2.00 | ≤0.045 | ≤0.030 | 17.00–19.00 | 9.00–12.00 | 4×(C+N)–0.70 |
Data source: ASTM A213-25 / ASME SA213 Table 1, TP321H row ≤ heat-analysis acceptance limits. Confirm the values against the ordered edition and the MTC.
Stainless Steel 321H 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.
5. Dimensional Standards & Tolerances
Manufactured to strict international standards:
Applicable Standards
- ASTM A213
- EN 10216-5 (D3/D4)
- ASTM A269
Typical Tolerances
- OD tolerance: ±0.10 mm to ±0.5%
- Wall thickness: ±7.5% to ±20%
- Length: per standard or customized
Ensures high precision for heat exchanger and pressure systems
6. Industrial Applications
TP321H seamless tubes are widely used in high-temperature and corrosion-resistant environments:
Power Generation
- Superheater tubes
- Reheater tubes
- Boiler components
Petrochemical Industry
- Furnace components
- Thermal reactors
- Expansion joints
Aerospace Industry
- Exhaust systems
- Engine components
- High-temperature liners
Heat Treatment & Furnace
- Retorts
- Muffles
- Furnace fixtures
Waste Incineration
- Combustion chambers
- Pollution control systems
Quality Assurance & Inspection
Each TP321H tube is strictly controlled and fully traceable:
Certification
- EN 10204 3.1 Material Test Certificates (MTC) as standard; 3.2 by arrangement
Testing & Inspection
- PMI (Positive Material Identification), when specified
- Ultrasonic Testing (UT), when specified
- Eddy Current Testing (ET), when specified
- Hydrostatic Testing, when specified
Advanced Metallurgical Testing
- Intergranular Corrosion (IGC) Test (ASTM A262 Practice E)
- Grain size analysis (ASTM E112)
Third-Party Inspection
- ABS
- DNV
- BV (Bureau Veritas)
- TÜV
- SGS
Frequently Asked Questions
What sizes are available for TP321H 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 TP321H seamless tube?
ASTM A213 / ASME SA213 is the governing specification for TP321H 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 TP321H 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.
