Aluminized steel tube is produced by applying aluminum-silicon coating on carbon steel, which is the main function of this coating. When carbon steel is dipped in molten aluminum, the result will be a compound, resistant to oxidation and resistant up to 675 degrees Celsius. USA Piping Solution offers aluminum steel tubes in SA1D coating class, at coating weights SA1D-80 and SA1D-120. For higher temperature or more corrosive application, stainless steel is the correct option. For more information about the wider family see the Automotive Steel Tubes .
What the Coating Does
Type 1 aluminized coating is an aluminium-silicon alloy, roughly 5 to 11 percent silicon, metallurgically bonded to the steel by hot dipping. The silicon is what keeps the coating thin and adherent rather than brittle. In service the aluminium forms a tight alumina skin that resists oxidation and scaling at temperatures where uncoated carbon steel would corrode away, while the steel underneath carries the strength and formability at a fraction of the cost of stainless. It is, in effect, a way to buy high-temperature oxidation resistance without buying stainless steel, wherever the temperature stays within the coating's range.
SA1D-80 or SA1D-120
| Class | Coating Weight | Choose It When |
|---|---|---|
| SA1D-80 | Lighter Type 1 Al-Si coating | General exhaust and heat-shield service where the standard coating life is sufficient |
| SA1D-120 | Heavier Type 1 Al-Si coating | Longer coating life and more demanding oxidation exposure; the more protective option |
Both are the same Type 1 aluminium-silicon coating on the same base steel; the number reflects coating weight, and therefore how much oxidation protection and life the coating gives. Heavier coating costs more and lasts longer in hot, oxidizing service. Confirm the coating-weight designation your OEM specification calls for, since naming conventions vary between mills and standards.
Specifications
| Coating Type | Type 1 aluminium-silicon (Al-Si), hot-dip |
| Coating Classes | SA1D-80 (lighter) and SA1D-120 (heavier) |
| Base Material | Low carbon steel; other base grades on request |
| Service Temperature | Oxidation resistance to approximately 675°C (1250°F) |
| Construction | Welded (ERW) tube typical; confirm requirement |
| Typical OD Range | Exhaust and heat-shield sizes; send your requirement |
| Formability | Retains steel formability for bending, flaring, and hydroforming |
Service temperature and coating designations above are commonly published values for Type 1 aluminized steel. Confirm the exact coating class and base grade against your OEM or mill specification when you order.
Applications
- Automotive Exhaust Systems: the largest use, from manifolds back through the cooler exhaust sections. See Automotive Steel Tubes for related grades.
- Heat Shields: under-body and engine-bay heat shielding.
- Furnace & Oven Hardware: recuperator tubes, radiant tubes, and internal hardware in the coating's temperature range.
- Combustion & Heating Equipment: burner and flue components.
- Agricultural & Industrial Dryers: hot-gas ducting and tube where oxidation resistance is needed at moderate cost.
Where Aluminized Stops and Stainless Begins
Aluminized steel's ceiling is roughly 675°C for oxidation, and its weakness is the cut edge and any breach in the coating, where the exposed steel can corrode, especially against acidic exhaust condensate. When the hot end of an exhaust runs hotter than the coating tolerates, or when condensate corrosion is the failure mode, the answer moves to ferritic stainless such as 409 or 439. For that step up, our Automotive Steel Tubes range and ferritic stainless grades cover the higher-duty options.
Send Coating Class, Size & Service Temperature →
Testing, Certification & Availability
Supplied with mill certification covering base steel and coating weight, with dimensional and coating checks; see our Quality Policy page. Send coating class (SA1D-80 or SA1D-120), OD, wall, length, and quantity for availability.
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Frequently Asked Questions
What is the difference between SA1D-80 and SA1D-120?
Coating weight. Both are the same Type 1 aluminium-silicon coating on the same steel; SA1D-120 carries a heavier coat, giving longer life and more oxidation protection in hot service. SA1D-80 suits general duty; SA1D-120 suits more demanding exposure.
How hot can aluminized steel tube run?
Type 1 aluminized (Al-Si) coating resists oxidation to roughly 675°C (1250°F). Above that, or where acidic condensate attacks cut edges, ferritic stainless such as 409 or 439 is the better choice.
Does the coating survive bending and forming?
Yes. The Al-Si coating is thin and adherent specifically so the tube keeps the base steel's formability for bending, flaring, and hydroforming. Severe forming can still stress the coating at tight radii, so discuss the forming operation with us if it is aggressive.
Is aluminized steel the same as galvanized steel?
No. Galvanized steel is zinc coated, for atmospheric corrosion resistance at ambient temperatures. Aluminized steel is aluminium-silicon coated, for oxidation resistance at high temperature. They solve different problems; aluminized is the exhaust-and-furnace material, galvanized is the outdoor-atmosphere material.