Galvanic coating and bead blasting!! PLEASE READ

[tobycat]

Just want to give everyone a warning about bead blasting  off galvanic coating.  I took my little 4130 chromoly scuba tank to a powdercoater to have the zinc/galv blasted off. I had already cut the door out so the inside of the tank was exposed and blasted as well.  Not sure if it was because he was using  an enclosed recirculating media cabinet but what I thought was a clean surface was not! While prepping/grinding the areas where I would be welding I discovered that the galvy was still there. Either re-deposited into the metal from dirty media or the guy just did a poor job. It was deceiving as the tank  "looked clean". I am now wet sanding the whole tank inside and out by hand.

 

[turnandburn]

what kinda media was used?

 

[dward51]

Ok before anyone says this.... Yes, I know what zinc poisoning is.

Since it's  small tank, why could you not do a burn out of the inside?  It's the heat that releases the fumes that cause the problem and I would think once it's released, it's releases.  So it seems logical you could burn it out in a high temp fire and be done with it.  Then look at bead blasting or sanding for final cleanup.

I'm no expert, but it sounded like a reasonable idea to me.

 

[tobycat]

I believe he used a garnet media not that it matters now, I have had galvanic/zinc poisoning once and that was enough. When I get this tank sanded down to fresh clean metal I will then burn it out. I just wanted everyone to be aware that even though its blasted there can still be a lot of coating left because it was re deposited or the person doing the blasting "thought" it was clean. I recommend hitting it with some #400 paper with water and any galv/zing will show up as grey patches/spots. Glad it's such a small tank and not my 60 gallon.  Will never use a coated tank again.