Seamless Stainless Steel TP309H Pipe
What is a Seamless Stainless Steel TP309H Pipe?
Seamless Stainless Steel TP309H Pipe is a high-chromium, high-nickel austenitic heat-resisting grade (approximately 23 % Cr – 13 % Ni) with a controlled carbon range of 0.04–0.10 %. Produced from a solid billet by hot piercing and cold drawing, it contains no weld seam, ensuring uniform performance under severe thermal cycling.
The elevated chromium and nickel content gives TP309H outstanding oxidation and scaling resistance in continuous service up to about 1000 °C, well beyond the capability of standard 304 or 316 grades. The H-carbon control provides additional elevated-temperature strength for pressure-retaining components in furnaces and flue-gas systems.
Manufactured to ASTM A312 and A213 (ASME SA312/SA213), TP309H seamless pipe is the material of choice for furnace parts, annealing equipment and high-temperature ducting where both scaling resistance and moderate pressure capability are required.
Stainless Steel TP309H vs TP310S vs TP304H: Positioning the Heat-Resisting Grades
Among austenitic heat-resisting grades, the choice between 309H, 310S and 304H follows the service temperature and the atmosphere involved.
| Grade | Key Chemistry / Condition | Where It Fits |
|---|---|---|
| TP309H | 23Cr-13Ni, C 0.04-0.10 % | Scaling resistance to about 1000 °C with H-grade strength for pressure parts |
| TP310S | 25Cr-20Ni, C ≤ 0.08 % | Highest scaling resistance of the conventional grades, to about 1050 °C; lower hot strength than the H grade |
| TP304H | 18Cr-8Ni, C 0.04-0.10 % | Economical choice for service up to about 800 °C |
| TP321H | 18Cr-10Ni-Ti | Stabilized high-temperature grade where repeated thermal cycling and welding coexist |
Product Specifications
Specification data for Seamless Stainless Steel TP309H Pipe is compiled from the governing ASTM/ASME/EN standards and our routine production records; typical values are shown where a standard leaves a limit open.
| Category | Standard / Designation |
|---|---|
| Seamless Pipe | ASTM A312 / ASME SA312 |
| Seamless & Welded Tube | ASTM A213 / ASME SA213 |
| UNS Designation | S30909 |
| Werkstoff Number | 1.4833 |
| EN Designation | X6CrNi23-13 |
Size and Weight Chart
| NPS | OD (mm) | SCH 40 WT (mm) | SCH 40 kg/m | SCH 80 WT (mm) | SCH 80 kg/m |
|---|---|---|---|---|---|
| 1/4" | 13.7 | 2.24 | 0.65 | 3.02 | 0.81 |
| 1/2" | 21.3 | 2.77 | 1.29 | 3.73 | 1.65 |
| 3/4" | 26.7 | 2.87 | 1.72 | 3.91 | 2.24 |
| 1" | 33.4 | 3.38 | 2.55 | 4.55 | 3.3 |
| 1-1/4" | 42.2 | 3.56 | 3.46 | 4.85 | 4.55 |
| 1-1/2" | 48.3 | 3.68 | 4.13 | 5.08 | 5.52 |
| 2" | 60.3 | 3.91 | 5.54 | 5.54 | 7.62 |
| 3" | 88.9 | 5.49 | 11.51 | 7.62 | 15.57 |
| 4" | 114.3 | 6.02 | 16.38 | 8.56 | 22.75 |
| 6" | 168.3 | 7.11 | 28.8 | 10.97 | 43.38 |
| 8" | 219.1 | 8.18 | 43.36 | 12.7 | 65.88 |
Weights are theoretical for seamless pipe (kg per metre) calculated from the nominal dimensions; actual weights vary within the dimensional tolerances shown below. Intermediate sizes and schedules between SCH 10S and SCH 160 are produced to order.
Chemical Composition
| Element | Min (%) | Max (%) |
|---|---|---|
| Carbon (C) | 0.04 | 0.10 |
| Manganese (Mn) | — | 2.00 |
| Silicon (Si) | — | 0.75 |
| Phosphorus (P) | — | 0.045 |
| Sulfur (S) | — | 0.030 |
| Chromium (Cr) | 22.00 | 24.00 |
| Nickel (Ni) | 12.00 | 15.00 |
| Iron (Fe) | Balance | — |
Mechanical Properties
| Property | Value |
|---|---|
| Tensile Strength, min | 515 MPa (75 ksi) |
| Yield Strength (0.2 % offset), min | 205 MPa (30 ksi) |
| Elongation in 2 in. / 50 mm, min | 40 % |
| Hardness (typical, annealed) | ≤ 217 HBW |
| Heat Treatment | Solution annealed, min 1040 °C, rapid cooling |
Physical Properties
| Property | Value |
|---|---|
| Density | 8.00 g/cm³ |
| Melting Range | 1400 – 1455 °C |
| Elastic Modulus | 200 GPa |
| Coefficient of Thermal Expansion (0–100 °C) | 14.9 µm/m·°C |
| Thermal Conductivity (at 100 °C) | 15.6 W/m·K |
| Specific Heat Capacity | 500 J/kg·K |
| Electrical Resistivity | 78 µΩ·cm |
Equivalent Grades
| Standard System | Designation |
|---|---|
| UNS | S30909 |
| Werkstoff Nr. | 1.4828 |
| EN | X15CrNiSi20-12 (H-modified) |
| JIS | SUS 309H equivalent |
Why TP309H Excels in Furnace and Flue-Gas Service
With roughly 23 % chromium and 13 % nickel, TP309H builds a dense, self-healing chromium oxide scale that resists oxidation in continuous service up to about 1000 °C — some 200 °C beyond the capability of standard 304 grades. The elevated chromium level also improves resistance to sulfidation in the low-oxygen, sulfur-bearing atmospheres typical of furnace flues, and the high nickel content stabilizes the austenite against embrittlement under repeated thermal cycling.
The seamless construction matters most where temperature gradients are steepest. Furnace rolls, radiant tubes, burner components and annealing equipment all experience cyclic expansion that would first attack a welded joint; a seam-free pipe distributes these stresses uniformly and delivers predictable service life.
Manufacturing Process
Our seamless production route for Seamless Stainless Steel TP309H Pipe follows these documented stages:
- Billet Selection & Inspection: Certified EAF/AOD-melted rounds are ultrasonically inspected for internal soundness before entering the mill.
- Hot Piercing & Extrusion: The solid billet is cross-roll pierced or hot extruded at about 1150-1200 °C to form a hollow shell, consolidating the structure without any weld seam.
- Cold Drawing / Pilgering: Successive cold-drawing or cold-pilgering passes reduce diameter and wall to final size with tight dimensional control.
- Intermediate Annealing: Stress-relief or intermediate anneals between passes restore ductility for further reduction.
- Solution Treatment: A final solution anneal (typically 1040-1100 °C for austenitic grades) followed by rapid quench dissolves carbides and restores the fully austenitic, corrosion-resistant structure.
- Pickling & Passivation: Scale is removed in an acid bath, leaving the uniform passive surface required for corrosion service.
- Straightening, Cutting & Testing: Pipes are straightened, cut to length, then verified by eddy-current/ultrasonic examination, hydrostatic pressure testing and full dimensional inspection.
Surface Finish Options
- Pickled & Annealed: Standard supply condition; uniform matte passive surface, ideal for further fabrication.
- Bright Annealed: Annealed in hydrogen atmosphere for a reflective, scale-free surface used in instrumentation and sanitary lines.
- Mechanically Polished: Grit 180-600 finishes for decorative and hygienic applications.
- Mirror Polished: A fully reflective finish for architectural and high-purity service.
Dimensional Tolerances
Delivered dimensions are verified against the tolerances below; tighter tolerances can be negotiated for instrumentation and precision applications.
| Dimension | Tolerance |
|---|---|
| OD, tube ≤ 25.4 mm (cold worked) | ± 0.10 mm |
| OD, tube 25.4 – 38.1 mm | ± 0.15 mm |
| OD, tube 38.1 – 50.8 mm | ± 0.20 mm |
| OD, hot-finished pipe ≥ 50.8 mm | ± 1 % of OD |
| Wall thickness | - 12.5 % under-tolerance (min-wall basis) |
| Straightness | ≤ 1 mm per metre |
| Cut length | + 10 / - 0 mm (fixed lengths) |
Common Industrial Applications
Because of its characteristic property profile, Seamless Stainless Steel TP309H Pipe is specified in the following industries and services:
- Furnace & Kiln Equipment: Radiant tubes, burner components, retorts and muffles operating in direct flame contact.
- Annealing & Heat-Treatment Plants: Roller rails, furnace conveyors and fixtures exposed to 800–1000 °C atmospheres.
- Power & Waste-Incineration Plants: Flue-gas ducting and superheater supports in high-temperature, sulfur-bearing service.
- Cement & Mineral Processing: Kiln inlet components and hot-gas handling piping subject to scaling conditions.
- Petrochemical Reformers: Transfer-line piping and hangers in steam-reforming service.
- Glass Manufacturing: Molten-glass contact hardware and exhaust systems where scaling resistance is critical.
Quality Assurance, Testing and Documentation
Every length of Seamless Stainless Steel TP309H Pipe passes through a documented quality-control chain before dispatch:
- Material Certification: EN 10204 3.1 mill test certificates are issued for every heat; 3.2 certification with third-party witness (TUV, SGS, BV) is available on request.
- Chemical & Mechanical Testing: Heat-level chemical analysis plus tensile, hardness and, where applicable, flattening, flaring and reverse-flattening tests per the governing standard.
- Non-Destructive Examination: 100 % eddy-current or ultrasonic testing and hydrostatic or pneumatic pressure testing in line with the standard's supplementary requirements.
- Dimensional & Visual Inspection: Full OD, wall thickness, ovality and length verification with visual surface inspection after pickling or finishing.
- Traceability & Marking: Heat numbers stenciled or banded on every length, maintaining complete melt-to-pipe traceability.
Export and Packaging
Pipes are bundled with steel strapping and fitted with plastic or steel end caps, then packed in seaworthy wooden cases or crates and secured in containers for long-distance ocean freight. Standard export documentation — commercial invoice, packing list, certificate of origin, mill test certificates and, where required, third-party inspection reports — accompanies every shipment. Container-load and bulk project orders receive priority production slots and consolidated shipping documentation.
Frequently Asked Questions
Q1. How does TP309H compare with TP310 in high-temperature service?
A: TP310 carries a higher chromium level (24–26 %) and can be used about 50–100 °C hotter in the most severe scaling conditions. TP309H offers similar metallurgy at a lower alloy cost and is generally sufficient for continuous service up to roughly 1000 °C.
Q2. Is TP309H suitable for aqueous corrosion service?
A: Its strength is heat resistance. In wet corrosive media, 309H offers general resistance similar to 304 but is outperformed by 316L in chloride environments. It is normally selected for temperature, not for aggressive chemical duty.
Q3. What heat treatment does TP309H pipe receive?
A: Each pipe is solution annealed at a minimum of 1040 °C and rapidly cooled to dissolve carbides and restore the full austenitic structure before final sizing and pickling.
Q4. Do you supply TP309H in heavy-wall furnace-tube dimensions?
A: Yes, heavy-wall schedules for radiant tubes and hanger assemblies are produced to order, with full dimensional inspection reports and EN 10204 3.1 certification.
Ready to Request a Quotation?
Send us your size range, wall thickness/schedule, standard and quantity for Seamless Stainless Steel TP309H Pipe, and our engineering team will respond with a detailed technical and commercial offer within 24 hours. Custom sizes, third-party inspection and full export documentation are part of our standard service.
