Seamless Stainless Steel TP309S Pipe (UNS S30908) – High-Temperature Oxidation-Resistant Alloy
1. Overview of Seamless TP309 Pipe
TP309 Seamless Stainless Steel Pipe is supplied for oxidation resistance for elevated-temperature service. The size range shown (OD 6–1016 mm; WT 0.5–65 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 A312 / ASME SA312. 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 via a seamless process from solid billets, including hot piercing and cold finishing, TP309 pipes offer a uniform metallurgical structure, consistent wall thickness, and superior pressure resistance, ensuring reliability under extreme thermal cycling and mechanical stress.
The alloy contains a high proportion of chromium (22–24%) and nickel (12–15%), forming a stable, protective oxide layer that significantly reduces scaling and metal loss at elevated temperatures.
2. Key Technical Advantages
Excellent High-Temperature Oxidation Resistance
Designed for continuous service up to 1038°C (1900°F) and intermittent service up to 1010°C (1850°F), providing outstanding resistance to oxidation and carburization.
Superior Thermal Stability
Maintains structural integrity under thermal cycling conditions, making it ideal for furnace and heat-treatment applications.
Good Corrosion Resistance
Offers improved resistance compared to TP304, particularly in sulfur-bearing and mildly corrosive environments.
High Pressure Integrity
The seamless construction has no longitudinal weld seam and conforms to ASTM A312 / ASME SA312 for high-pressure piping systems.
Creep Resistance & Durability
Retains mechanical strength at elevated temperatures, ensuring extended service life in high-stress environments.
Non-Magnetic Austenitic Structure
Remains non-magnetic in annealed condition, suitable for specialized industrial and electrical applications.
Product Specifications and Data
To provide a comprehensive overview of this material, here are the detailed technical specifications and performance data for 309 stainless steel.
Equivalent Grade
| UNS | Common grade name | EN material number | EN steel name | JIS grade | GB/T grade |
|---|---|---|---|---|---|
| S30908 | 309S | 1.4833 | X12CrNi23-13 | SUS309S | 06Cr23Ni13 / 0Cr23Ni13 |
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. See the grade designation index.
Chemical Composition
The composition of Stainless Steel 309 is carefully balanced to achieve its superior high-temperature oxidation resistance and strength.
| Cr | Ni | P | S | Mo | Cu | Mn | Si | C |
|---|---|---|---|---|---|---|---|---|
| 22.00 – 24.00 | 12.00 – 15.00 | ≤0.045 | ≤ 0.030 | ≤ 0.75 | – | ≤ 2.00 | ≤1.00 | ≤ 0.08 |
Data source: ASTM A312/A312M Table 1, TP309S (UNS S30908) row — heat-analysis acceptance limits: C ≤ 0.08, Mn ≤ 2.00, P ≤ 0.045, S ≤ 0.030, Si ≤ 1.00, Cr 22.0–24.0, Ni 12.0–15.0, Mo ≤ 0.75. ASTM A312 covers TP309S (S30908) and TP309H (S30909, C 0.04–0.10); there is no plain “TP309” grade in A312. The grade, standard edition and heat analysis actually supplied are stated on the quotation and MTC.
Typical Mechanical Properties
Stainless Steel 309 is specifically designed to maintain its strength and shape in high-stress, high-temperature environments.
| Tensile Strength (min) | Yield Strength (min) | Elongation (min, longitudinal) | Hardness (max) |
|---|---|---|---|
| 75 ksi [515 MPa] | 30 ksi [205 MPa] | 35% | 192 HBW / 200 HV / 90 HRB |
Note: Typical values for reference only — not acceptance limits. Mechanical properties are reported on the MTC against the ordered standard, product form, condition and test temperature.
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 | 1300 – 1390 °C approx. | 16.5 μm/m·°C (20-100°C) | 13.9 W/m·K (20°C) | 195 GPa | 0.85 × 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.
Size Tolerance Chart (mm)
| NPS Designator (Inches) | Permissible Variations in Outside Diameter (Inches) |
| 1⁄8 to 1 1⁄2, inclusive | Over: 1⁄64 in. (0.015 in.) |
| Under: 1⁄32 in. (0.031 in.) | |
| Over 1 1⁄2 to 4, inclusive | Over: 1⁄32 in. (0.031 in.) |
| Under: 1⁄32 in. (0.031 in.) | |
| Over 4 to 8, inclusive | Over: 1⁄16 in. (0.062 in.) |
| Under: 1⁄32 in. (0.031 in.) | |
| Over 8 to 18, inclusive | Over: 3⁄32 in. (0.093 in.) |
| Under: 1⁄32 in. (0.031 in.) | |
| Over 18 to 26, inclusive | Over: 1⁄8 in. (0.125 in.) |
| Under: 1⁄32 in. (0.031 in.) | |
| Over 26 to 34, inclusive | Over: 5⁄32 in. (0.156 in.) |
| Under: 1⁄32 in. (0.031 in.) | |
| Over 34 to 48, inclusive | Over: 3⁄16 in. (0.187 in.) |
| Under: 1⁄32 in. (0.031 in.) |
Tolerance basis: permitted variations per the governing specification stated on this page and the applicable general-requirements standard (ASTM A999 / ASME SA999) for the ordered product form; the wall-thickness and length variations in this section follow the same basis.
The wall thickness tolerances are defined by the nominal wall thickness (t) and the outside diameter (D).
1. Minimum Wall Thickness
The minimum wall thickness at any point on the pipe shall not be more than {12.5%} under the nominal (specified) wall thickness.
2. Maximum Wall Thickness (Percentage Over Nominal)
The maximum allowable wall thickness variation depends on the size and the t/D ratio (ratio of nominal wall thickness to ordered outside diameter):
| NPS Designator (Inches) | t/D Ratio | Permissible Variation (Over Nominal WT) |
| 1/8 to 2, inclusive | All ratios | +20.0% |
| 3 to 18, inclusive | t/D ≤ 5% | +22.5% |
| 3 to 18, inclusive | t/D >5% | +15.0% |
| 20 and larger (Seamless) | t/D ≤ 5% | +22.5% |
| 20 and larger (Seamless) | t/D >5% | +15.0% |
| 20 and larger (Welded) | All ratios | +17.5% |
For pipe ordered to a Specific Cut Length, the standard tolerance is +1⁄8 in. [3.2 mm], -0 in. [0 mm].
Pipe is typically supplied in Single Random Lengths (17 to 24 ft) or Double Random Lengths (38 to 40 ft), unless otherwise specified.
Disclaimer: These tolerances are based on ASTM A999/A999M general dimensional requirements commonly referenced by ASTM A312 and ASTM A790. The full and most current specification document must always be consulted for official design and procurement purposes.
Industrial Applications
Seamless TP309 pipes are widely used in high-temperature and heat-processing industries:
Furnace & Thermal Processing
Furnace linings, radiant tubes, heat shields, muffle tubes
Power Generation
Boiler components, hangers, and thermal oxidizers in coal-fired and biomass plants
Petrochemical Industry
Catalytic systems, hot gas handling, and acid processing equipment
Cement & Kiln Industry
Rotary kilns, kiln linings, cooling systems
Automotive & Exhaust Systems
High-temperature exhaust manifolds and thermal reactors
Quality Assurance & Certification
Testing scope is agreed on the purchase order and carried out against the ordered standard:
Material Certification
EN 10204 3.1 Mill Test Certificate (MTC) as standard, 3.2 by arrangement
Full heat traceability from raw material to finished product
Non-Destructive Testing (NDT)
- Ultrasonic Testing (UT)
- Eddy Current Testing (ET)
- Hydrostatic Testing (HT)
- Positive Material Identification (PMI)
Mechanical & Metallurgical Testing
- Grain size analysis (ASTM E112)
- Intergranular Corrosion (IGC) testing
- Flattening and flaring tests
Third-Party Inspection
Available on request — ABS, DNV, BV, TÜV, SGS, Lloyd’s Register
Frequently Asked Questions
What sizes are available for TP309 seamless pipe?
The overall range is OD 6–1016 mm; WT 0.5–65 mm. Requirements outside this range are reviewed against mill capability on request.
Which specification governs TP309 seamless pipe?
ASTM A312 / ASME SA312 is the governing specification for TP309 seamless pipe. 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 NPS and schedule (or actual OD and wall), 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 tube form, see the TP309 seamless tube. To compare other grades and size combinations, browse the Stainless Steel Seamless Tube category. Minimum order quantity and lead time are confirmed on enquiry against the ordered grade, size and quantity.
