Steel tank rust, how bad, what to do?

[HM_legon]

I picked up some LP95s, and I noticed a little bit of rust on the bottom of one of the tanks, nothing major, or so I think.

Anybody able to chime in and give their 2 cents on if i should worry about it, sand it & put clear coat or something on the area?

They are in hydro and lapsed vis, do you think they would pass vis as is or is this too egregious left untreated.

Thanks,
Legon

 

[runsongas]

you can attempt to clean it off and cold galv paint it

if you are diving fresh water exclusively, less of a need to

 

[HM_legon]

you can attempt to clean it off and cold galv paint it

if you are diving fresh water exclusively, less of a need to

Yep, no plans to be in any saltwater any time soon, especially not with these tanks. I think I'll give it a light sand and look into the cold galv painting. I'd like to explore stripping off all paint and redoing the finish so any advice on how to do that is welcome.

 

[Valerii Vakshul]

Excellent working tanks. Apart from the inscription that these are my tanks, I wouldn't do anything.

 

[Scared Silly]

Looks like the typical cylinder boot rust. Looks to have done a number of the epoxy paint. I would clean them up with a wire brush and try get all of the lose paint along the edges. The cold galv paint or epoxy paint them.

 

[Eric Sedletzky]

You need to sand blast the rust completely off and either cold galvanize it or better yet epoxy primer (a true epoxy 1:1 or 2:1 two part) and then top coat it with a two part linear aliphatic polyester urethane like Awl Grip.
Then you'll need to send it to hydro to make sure it's safe.
You might be able to wire brush the rust out but you need to use a stiff wheel brush on a grinder. Doing anything by hand is a waste of time.
You have to get rid of all the rust and/or neutralize it or it will just continue to eat away. Don't put that boot back on until you treat the rust and coat it. I would trim down the boot if it's one of those skin tight ones that's tall and slip it iff after every use and let the paint dry out and breathe.

 

[HM_legon]

You need to sand blast the rust completely off and either cold galvanize it or better yet epoxy primer (a true epoxy 1:1 or 2:1 two part) and then top coat it with a two part linear aliphatic polyester urethane like Awl Grip.
Then you'll need to send it to hydro to make sure it's safe.
You might be able to wire brush the rust out but you need to use a stiff wheel brush on a grinder. Doing anything by hand is a waste of time.
You have to get rid of all the rust and/or neutralize it or it will just continue to eat away. Don't put that boot back on until you treat the rust and coat it. I would trim down the boot if it's one of those skin tight ones that's tall and slip it iff after every use and let the paint dry out and breathe.

I don't have any tank boots. I do have access to a sand blaster. Should I empty the tanks first and then take the valves off? Would it be better to just blast all the paint off and re do the paint entirely? If I take off the valves should I put one of those little plastic valve thread protectors for when I'm blasting it?

 

[Still Kicking]

I don't have any tank boots. I do have access to a sand blaster. Should I empty the tanks first and then take the valves off? Would it be better to just blast all the paint off and re do the paint entirely? If I take off the valves should I put one of those little plastic valve thread protectors for when I'm blasting it?

Focus on the areas where the rust is. No need to drain and fully strip the paint that is intact unless you love doing dirty work. Unlikely you will achieve anything as good as the original finish.

On a separate note, does anyone have any experience/opinions on Ospho (phosphoric acid)?

I used it on my boat trailer and then sprayed with zinc paint. It came recommended and seemed to do a good job.

 

[Eric Sedletzky]

Focus on the areas where the rust is. No need to drain and fully strip the paint that is intact unless you love doing dirty work. Unlikely you will achieve anything as good as the original finish.

On a separate note, does anyone have any experience/opinions on Ospho (phosphoric acid)?

I used it on my boat trailer and then sprayed with zinc paint. It came recommended and seemed to do a good job.

Actually, you CAN achieve an OEM factory spec finish if you do it the way I've oultlined.
They are using paint chemistry very similar ir identical to the products I use. An aliphatic linear polyester urethane finish is what they use over an epoxy DTM (direct to metal) primer. If you can find an 80% zinc dust 2 part epoxy resin primer even better.
Benjamin Moore industrial coatings used to have a zinc epoxy primer but it's not available in CA anymore, shame because it was damn good stuff for this application. It was the MEK in it.
I had a marine business and have been in the auto body and industrial refinishing business my whole life. I know this stuff.
One thing is none of this stuff is cheap. By the time you buy everything you need you could probably just buy a new tank and be ahead.
I already have the stuff laying around because I have left over from other jobs.

 

[Eric Sedletzky]

I don't have any tank boots. I do have access to a sand blaster. Should I empty the tanks first and then take the valves off? Would it be better to just blast all the paint off and re do the paint entirely? If I take off the valves should I put one of those little plastic valve thread protectors for when I'm blasting it?

Yes, drain the tank and put an old valve in for working on it or a plug.
Sand blast the areas that need it and orbital sand the unaffected areas with 180-220 grit.
Feather out the paint where you sand blasted to bare steel. You can hand apply the primer with roll/brush and or spray it.
I'd get all the bare steel spots primed then take it to hydro. After it passes then scuff/sand prep the primer and spray on one more coat over the while tank as a sealer, wait an hour then topcoat right over it.