External rust, stripping & painting steel tanks

[Ben_ca]

That tank is hot dipped, with adhesion failure at the stamp. Wire brush the stamp and ZRC coat the area a couple of times.

FT

Thanks Fred... That's what I thought... I'm supprised to see that the coating is that thick. Should I do it before or after hydro? or does it matter? It's actually cleaning up really nicely... all the white spots are superficial and come off with a little elbow grease

 

[FredT]

Do it after, that way you protect the "new" stamps as well. Don't forget to "feather" the edges of the failed coating. The failure was probably due to the WAY oversize hydro stamps used, and a bit of excess exuberance on the part of the guy swinging the maul when that hydro was done. I've seen that symptom before.

The white spots don't matter corrosion wise as long as the coating under it is sound.

 

[Ben_ca]

Do it after, that way you protect the "new" stamps as well. Don't forget to "feather" the edges of the failed coating. The failure was probably due to the WAY oversize hydro stamps used, and a bit of excess exuberance on the part of the guy swinging the maul when that hydro was done. I've seen that symptom before.

The white spots don't matter corrosion wise as long as the coating under it is sound.

The white spots are pretty much gone... came off pretty easily with a wire brush. I'll post some before and after pictures soon.

Anyone in Northern CA with some ZRC to spare?

 

[inletsurf]

For those who don't understand what galvanizing is, zinc, which is highly resistant to corrosion, is electrochemically bonded to the steel tank.

Zinc is highly susceptible to corrosion and is the reason why it is typically the #1 sacrificial metal used in marine applications. Maybe you ought to do some research? Here's a link which may help you to understand it better.
http://www.corrosionsource.com/handbook/galv_series.htm