ASTM A268 TP446 Stainless Steel Welded Pipe Specification
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Looking for a reliable ASTM A268 TP446 stainless steel welded pipe supplier?GNEE supplies high-quality TP446 welded pipes with competitive pricing, fast delivery, and complete inspection documentation for industrial furnace, petrochemical, and heat exchanger projects worldwide.
What is ASTM A268 TP446 welded pipe?
ASTM A268 TP446 welded stainless steel pipe is designed for continuous high-temperature service requiring oxidation resistance, dimensional stability, and a long service life. It serves as a cost-effective alternative to high-nickel austenitic stainless steels in many furnace and heat-treatment applications.
Many buyers encounter:
• Weld seam cracking after long-term service
• Oxidation scaling above 1000°C
• Inconsistent chromium content
• Poor dimensional tolerance
• Lack of EN10204 3.1 certificates
• Delayed delivery for custom sizes
High Temperature 1100°C Ferritic Tube Supplier
The TP446 welded stainless steel tubes we supply are manufactured using a fully automated TIG welding process, supplemented by 99.99% high-purity argon gas shielding, to minimize chromium burnout and ensure the chemical composition of the weld seam remains as consistent as possible with the base metal. Unlike conventional processes, all tubes undergo full-tube online solution annealing immediately after welding, which completely eliminates residual welding stresses, refines the internal grain structure, and fundamentally prevents weld embrittlement and failure.
TP446 stainless steel round tubes feature a 23%–27% chromium content and a ferritic microstructure, exhibiting outstanding oxidation resistance at continuous operating temperatures up to 1100°C (2010°F). Compared with austenitic stainless steels, TP446 has a lower coefficient of thermal expansion and better thermal fatigue resistance, thereby reducing deformation during repeated heating and cooling cycles and extending service life.
TP446 welded tubes supplied by GNEE cover a wide range of sizes with outer diameters from 6 mm to 630 mm and wall thicknesses from 0.5 mm to 20 mm, and are available in various surface conditions such as annealed and pickled (AP), bright annealed (BA), and customized surface treatments.
ASTM A268 TP446 Welded Pipe Specification
Standard: ASTM A268 / A268M
Grade: TP446 (UNS S44600)
Product Form: Welded Pipe (ERW, EFW, or TIG Welded)
Steel Type: Ferritic Stainless Steel
OD Range: 6.0 mm – 219.1 mm (1/4" to 8" NPS)
Wall Thickness: 0.5 mm – 12.7 mm (Sch 5S, 10S, 40S, 80S)
Surface Condition: Annealed and Pickled (AP), Polished (Grit 180, 240, 320, 400).
Chemical Composition of ASTM A268 UNS S44660 Steel Pipe
| C % | Mn % | P % | S % | Si % | Cr % | Ni % | Mo % | N % | Ti+Nb % |
| 0.03 max | 1.00 max | 0.040 max | 0.030 max | 1.00 max | 25.0-28.0 | 1.00-3.50 | 3.00-4.00 | 0.04 | 0.20-1.00, & 6(C+N) min |
ASTM A268 TP446 Steel Pipe Mechanical Properties
| Grade | Tensile Strength (MPa) min | Yield Strength 0.2% Proof (MPa) min | Elongation (% in 50mm) min | Hardness | |
| Rockwell B (HR B) max | Brinell (HB) max | ||||
| 446 | 485 | 275 | 20 | 92 | 201 |
UNS S44600 Heater Tubes Creep Properties
| 1% Elongation1) for | Rupture2) for | ||||
|---|---|---|---|---|---|
| Temperature °C | 1,000 h N/mm2 | 10,000 h N/mm2 | 1,000 h N/mm2 | 10,000 h N/mm2 | 100,000 h N/mm2 |
| 500 | 80 | 50 | 160 | 100 | 55 |
| 600 | 27.5 | 17.5 | 55 | 35 | 20 |
| 700 | 8.5 | 4.7 | 17 | 9.5 | 5 |
| 800 | 3.7 | 2.1 | 7.5 | 4.3 | 2.3 |
| 900 | 1.8 | 1.0 | 3.6 | 1.9 | 1.0 |
Is TP446 welded pipe magnetic?
Yes, as a ferritic stainless steel, TP446 is strongly magnetic in all conditions (including the annealed state and after welding).
What are the differences between TP446 and TP310S stainless steel pipes?
Compared to TP310S, TP446 exhibits lower tensile strength and greater brittleness at room temperature. Both grades withstand oxidation and scaling at very high temperatures (approximately 1100°C–1150°C / 2000°F–2100°F). However, TP446 performs exceptionally well in environments containing sulfurous gases or molten copper; in contrast, TP310S excels under conditions of severe thermal cycling and maintains its structural integrity.
Common Applications
Furnace components: heat recuperators, burner nozzles, and kiln linings.
Power generation: boiler tubes and high-temperature heat exchangers.
Industrial processing: refinery heater tubes and gas turbine components.
If you have a need for any of the above items, please let me know:
What schedule/wall thickness and outer diameter (OD) are you looking for?
What temperature or corrosive environment will the pipe be exposed to?
Do you need standard mill lengths, or cut-to-order lengths?
ASTM A268 TP446 Stainless Steel Welded Pipe Export Records
| Destination Country | Product Description | Size | Quantity | Industry | Inspection |
|---|---|---|---|---|---|
| South Korea | ASTM A268 TP446 Stainless Steel Welded Pipe | OD 89 × WT 4.0 mm | 58 Tons | Industrial Furnace | EN 10204 3.1, PMI |
| Vietnam | TP446 Welded Heat Resistant Pipe | OD 76 × WT 3.5 mm | 42 Tons | Heat Exchanger | SGS, Hydro Test |
| Turkey | ASTM A268 TP446 Welded Pipe | OD 114.3 × WT 5.0 mm | 36 Tons | Petrochemical Plant | PMI, Eddy Current Test |
| United Arab Emirates | TP446 High-Temperature Exhaust Pipe | OD 168.3 × WT 6.0 mm | 25 Tons | Power Plant | BV Inspection |
| India | TP446 Stainless Steel Welded Tube | OD 60.3 × WT 2.8 mm | 31 Tons | Heat Treatment Furnace | EN 10204 3.1 |
Customer Feedback: 475°C Embrittlement of TP446 Steel Pipe
To address the challenges of temperature fluctuations between 400°C and 500°C-as well as the issue of 475°C embrittlement-encountered during frequent start-stop cycles and maintenance operations, we optimized the smelting formula through the precise addition of nitrogen to refine ferrite grains, thereby significantly enhancing the material's impact resistance. Real-world customer validation demonstrates that the damage rate of our tubing during maintenance is more than 20% lower than that of comparable products.
Quality Testing
Flattening Test: A section of welded pipe is flattened between parallel plates at ambient temperature to ensure no cracks or defects appear in the weld seam or the specimen.
Flaring Test: For pipes within a specific diameter range, the pipe end must withstand flaring without developing cracks or defects.
Hardness Test: Specimens from each batch are tested.
Hydrostatic Test or Non-destructive Electrical Testing: All pipes (100%) must undergo hydrostatic testing or eddy current/ultrasonic testing to ensure leak-tight integrity.
High-quality packaging
Packaged in bundles or plywood crates, wrapped in plastic, and provided with appropriate protective measures to ensure suitability for seaworthy transport, or packed according to specific requirements.
Marking shall comply with the provisions of Specification A1016/A1016M and indicate whether the pipe is hot-worked or cold-worked; markings shall include, but are not limited to: standard, grade, size, heat number, and lot number.
