USA Piping Solution supplies Ferritic SS 446 pipes and tubes to ASTM A268 for general service, and to ASTM A213 where the application is boiler, superheater, or heat-exchanger tube. At 23 to 27% chromium, roughly double what 441 or 444 carry, 446 is built for one job: standing up to oxidation and scaling at sustained temperatures from about 1500 to 2100 deg F. Every heat ships with full mill certification and traceability. For the automotive exhaust grade, see our Ferritic SS 441 Pipes & Tubes, and for the heat exchanger and hot water grade, see Ferritic SS 444 Pipes & Tubes.
Specification
| Specification | Details |
|---|---|
| Standard | ASTM A268 / ASME SA268 (general service); ASTM A213 / ASME SA213 (boiler, superheater, heat-exchanger tube) |
| UNS | S44600 |
| EN / Werkstoff Nr. | 1.4762 |
| Type | Ferritic, high-chromium, non-hardenable |
| Form | Seamless and welded tube; pipe on request |
| Service temperature | Approximately 1500 - 2100 deg F (816 - 1149 deg C) |
| Defining use | Furnace and kiln components, oil burners, turbine parts, boiler soot blowers |
For boiler and heat-exchanger tube in other alloy families, see our Boiler & Heat Exchanger Tubes category, or browse the full Stainless Steel Pipes & Tubes range.
Why 446 for Extreme High-Temperature Service
446's chromium content is set high specifically to resist scaling in continuous high-temperature oxidizing atmospheres, well beyond what 441 or 444 are built for. It also holds up against oil-ash corrosion and resists attack from molten copper, lead, tin, and brass, which is why it turns up in oil burner components and glass mold tooling as much as in boiler and turbine parts.
The tradeoff is toughness at room temperature and the standard ferritic limitation on fabrication: 446 is not intended for the kind of forming and welding-heavy work that 441 sees in automotive exhaust manufacturing. It's specified for the temperature range, not general-purpose fabrication.
Applications
- Furnace & Kiln Components: muffles, retorts, and fixtures operating continuously at high temperature.
- Oil Burner Parts: components exposed to combustion-side heat and oil-ash corrosion.
- Turbine Parts & Boiler Soot Blowers: stationary components in steam boiler systems.
- Glass Mold Tooling: molds exposed to sustained contact with molten glass.
For boiler and superheater tube more broadly, see our Boiler & Heat Exchanger Tubes category.
Have a Spec Calling Out A213 TP446? Send It Over
Testing & Availability
Every heat is tested and mill certified to ASTM A268 or A213 as specified; see our Quality Policy page for the full testing program we run across all grades. Send us your OD, wall thickness, and length requirement and we'll confirm current mill availability and lead time.
Related Products
- Ferritic SS 441 Pipes & Tubes
- Ferritic SS 444 Pipes & Tubes
- Boiler & Heat Exchanger Tubes
- Stainless Steel Pipes & Tubes
Frequently Asked Questions
What's the practical temperature limit for SS 446?
446 is commonly used from about 1500 to 2100 deg F (816 to 1149 deg C) in continuous oxidizing service. Above that range, or in cyclic or reducing atmospheres, confirm suitability with your metallurgist since high-chromium ferritics can be prone to embrittlement under certain thermal cycling conditions.
Is SS 446 tube covered by ASTM A213 as well as A268?
Yes. A268 is the general ferritic tubing standard; A213 specifically covers seamless ferritic and austenitic alloy steel boiler, superheater, and heat-exchanger tube, and TP446 is a listed grade under it.
What sizes are available in SS 446 tube?
Send us your OD, wall thickness, and length requirement and we'll confirm current mill availability and lead time.