ALUMINUM BLOWER PAINTING

[chrysa1975]

We have a blower from aluminum alloy and it will be installed in a heavy marine environment. Vendor said that all parts can receive paint according to ISO 21944 C5, but I think that maybe the performance of the blower will be affected. The thickness of the painting system will be around 300 μm. Do you know if the impeller and rest parts of the blower can receive painting?

 

[TugboatEng]

It's best to leave aluminum bare in marine environments.

 

[chrysa1975]

Dear TugboatEng, thank you very much. Do you think Anodized coating Class AA15 per UNI EN ISO 7599 would be also a problem?

 

[TugboatEng]

Any kind of coating on aluminum sets up a crevice corrosion potential. The correct alloys (5052, 5086, and 6061) do quite well at protecting themselves when left uncoated and out in the open. Look up some pictures of aluminum boats and ships. You'll find the commercial ones to mostly unpainted except for the anti-fouling on the bottom.

 

[EdStainless]

The coating that work are usually multi layer (prime/binder, protect, seal) with each layer inspected for voids.
As TBE said the slightest nick or void will result is aggressive localized corrosion.
I hope that this unit was designed for marine use and made from a 5xxx series type alloy.
To your original question, coatings are rarely thick enough to impact performance. So unless this is a very small blower I can't see that being an issue.
I have had issues with coated impellers and balance, because you are not allowed to grind or drill after coating.

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P.E. Metallurgy, consulting work welcomed

 

[chrysa1975]

Gentlemen this week you helped me more than enough! Thank you again!