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Unusual Flaking on surface of steel beam

Unusual Flaking on surface of steel beam

Unusual Flaking on surface of steel beam

Hi guys,

I am seeking some advice for a steel beam that appears to have something going on with its surface (see below picture.)

We were rectifying some damage to a garage and removed plasterboard to the area to discover this steel beam with what appears to be flaking to its surface.

Does anyone have any experience with this? Is it normal? Does it pose any potential issues? Would really appreciate any feedback guys.


RE: Unusual Flaking on surface of steel beam

Steel Beam? I see metal purlins, wood trusses, garage door opening track, and ceiling grid.

I also see what could be the bottom flange of a steel beam, but it does not make any sense with the framing that I can see...

The discoloration I do see could be staining from condensation onto the beam.

Mike McCann, PE, SE (WA, HI)

RE: Unusual Flaking on surface of steel beam

A close up would help but this mottling or flaking seems very superficial to me. Just clean it off with a wire brush or pin machine and repaint.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Unusual Flaking on surface of steel beam

Close up / better photo / photo from another angle would be great.

If I think I'm looking at the item in question it looks like condensation patches which are stained. I don't see anything I'd be immediately concerned about.

RE: Unusual Flaking on surface of steel beam

If my eyes didn't cheat me, the stain look dots can be shallow dents too. Which could be weird, but I don't see structural concerns unless in a corrosive environment.

RE: Unusual Flaking on surface of steel beam

Maybe mill scale?

RE: Unusual Flaking on surface of steel beam

Is this a hot-dip galvanized beam? If so, the non-uniform appearance may be due to galvanizing.

RE: Unusual Flaking on surface of steel beam

Thanks for the responses guys. I believe the steel has been painted. I'm not too concerned with the Structural Integrity of the beam at this point in time. Im more concerned about corrosion from taking place. The dwelling isnt located in a highly corrosive zone (C2 using the below table - Austrlian Standards) so i'm not sure if it will pose any issues over the life of the structure. The rectification works are not related to this particular beam so im guessing the owner will not want to do any works to it unless its entirely necessary.

Once again, appreciate the feedback/help guys.

RE: Unusual Flaking on surface of steel beam

If it's indoors in a minimally corrosive environment, it'll last a long time. The rust that's forming under the paint probably isn't that bad. That being said, it's always a best practice to scrape loose paint/rust and at least apply a primer. Spending the extra money on a zinc rich (ASTM A780?) primer would probably be a luxury in this case.

RE: Unusual Flaking on surface of steel beam

It looks to me like the bot. flg. of the beam was spattered with something, at one time or another, and now those small areas/spots are a little more reactive in terms of rusting. I don’t see any large area of scaling/flaking in your photo. If you are really concerned, take some scrapings of some of those spots and have a testing lab tell you what they find in the way of contaminants. They can probably also suggest some remedies.

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