Acid to remove galvanising?

[Kent]

Is the dust created by grinding galvanising toxic ?

most probably it is but no grinding dust will do your lungs much good and galvanised acid vapours might be a lot worse. Given the choice against acid (having had an industrial chemist and close friend give me the low down and true facts previous) the way forwards for me personally are crystal two guys don't sound bad. I used to grind for days let alone hours when I started work as an apprentice and nobody ever mentioned vibration outside of the blue jokes in the brew room

 

[Liquid Metal]

Not sure about that one in all honesty lol. The fumes given off from welding it are awfull, ive fallen foul of it a couple of times now and heavy metal poisoning is evil, like the worst dose of flu youve ever had for about 48hrs. All due to an overload of zinc in your system.
Cant see the dust being any good for you tbh. Also the fact that dust in your lungs can lead to all manner of problems there.

If this has come down to a case of acid = quick and cheap vs grinding labour intensive = slightly higher labour cost,

After some of the cracking advice ive read that he has dished out, Im sure Welderpaul will take the sensible route ie little more time and grind it off, and not expose his guys to concentrated acids without sending them on all the necesary safety courses, like a lot of business owners would, thinking of lining their own pockets and treating staff as a replacable entity

 

[Dcal]

Sorry for the thread resurrection, but it was the first that came up on a search.

I needed to remove some hot dip galv from scaffold tube that I wanted to tig weld.

Anytime I have tried removing galv by grinding, the tungsten immediately gets a blob of zinc, so this time I ground the galv, then dipped it in sulphuric acid.

It welded fine (well as fine as my tig welding will get me) with no zinc contamination at all.

However, after dipping I got this strange copper looking stainning on the tube.

Anyone know what it is?
Just curious.
It didn't effect the weld (I think)

 

[Seadog]

Vinegar, citric acid, phosphoric acid hydrochloric acid (brick cleaner), sulphuric ( battery) acid...

 

[Misterg]

after dipping I got this strange copper looking stainning on the tube

It looks like copper depositing out of the acid. Have you ever used the acid for pickling copper or brass?

 

[julianf]

Since i posted on this thread, on the first page, im getting notifications -

After all this time, i can, with certainty, say that a NaOH solution strips zinc. I have used this to take off zinc for welding.


But, with relevance now, i can also say, again, with certainty, that NaOH does not strip copper (i have small bits of copper pipe in my biofuel reactor, and that has had NaOH solutions in it for 15+ years)

 

[charlysays]

Scraping the barrel for ideas now i think, does anyone know of an acid that will eat off hot dip galvanising?

It's looking like we are going to be grinding off galv from the top flanges of around 12T of beams otherwise

Ta

A bath of 10% phosphoric acid worked well to easily remove hot dip for me.
If I was removing it in situ I would probably use kitchen or toilet paper and pour the acid onto that to keep it in place then put some plastic over it to stop it drying out. Will take off the galve no probs.

 

[Dcal]

It looks like copper depositing out of the acid. Have you ever used the acid for pickling copper or brass?

It was pretty clean, I only used it to see if it would sharpen files (which it did) but I don't know if the files were contaminated with anything.

I wonder if the tubes had a thin coat of copper plating before the zinc?
Seems unlikely given this is just bog standard scaffold to use.

However, it seems to be present where I didn't grind but where the acid removed the zinc.
As @julianf says it won't strip copper so there might be something in it.