How to test for ALUMINIZED exhaust tubing

[joe28704]

How can someone confirm/test that an exhaust tubing has been "Aluminized" when visual observation is not conclusive?
Can it be tested with household/automotive/workshop chemicals ?
The "coating" does not appear to be hot dipped but perhaps plated and very thin if it's there at all.
Tubing is said to be formed from aluminized sheet coil then welded seam re-aluminized. I do not know the industrial processing specifications. I would like to know if I got what I paid for.
Thanks for any help.

 

[TugboatEng]

Buy some aluminized tubing and use it as an optical comparator. Aluminized tubing has a distinct appearance, whitish in color vs bare steels.

A less NDT method would be to wipe it with a caustic solution such as sodium hydroxide or oven cleaner. That should strip any aluminum off the surface. Steel alloys will have minimal effect from the caustic solution.

 

[bobjustbob]

I wonder if a copper sulfate solution would accomplish what you want. It is a test we would use to detect free iron on stainless steel. It should not work if the tubing is made of stainless. The free iron causes copper to precipitate out and deposit on the steel. The copper sulfate is root killer that you can get at the hardware store. You would need a bit of sulfuric acid to make the solution.

Bob