External rust, stripping & painting steel tanks

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Fishkiller

Contributor
Messages
1,169
Reaction score
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Location
Mesa Arizona, The all beach no ocean state.
# of dives
100 - 199
I was looking at my plane white LP121 steel tank and thought hey paint it like a Watermellon, get it O2 Chicken cleaned and use it for a EANx tank. I will just go down to the store and get some spray paint and tapeto give it a two tone design, then give it a clear coat over it all.. Now the question is do I need to have it hydro'd again??
 
There are two issues with paint on tanks.
(1) Paint hides stuff. Realize that any time you paint you potentially provide an area for undetected rust or corrosion. Not such a big deal with AL tanks, but some serious rust can grow under paint on steel. For that reason use a paint with a rust inhibitor in it - and clean the tanks clean, clean, clean and make sure they're absolutely completely totally dry before painting - and don't paint on a humid day.
(2) Temperature - many paint processes - especially commercial - involve baking on the paint. This is an ABSOLUTE NO-NO with scuba tanks. It weakens the metal and can and HAS resulted in tanks exploding and killing people during fills. For this reason, fill stations may be reluctant to fill any tank that isn't factory painted with a color they can recognize as a regular factory color.
Painting at room temperature with epoxy or spray paint doesn't warrant a hydro, unless your prep has involved sanding - sanding the tank warrants a hydro. You may have to get a hydro after painting anyway before the fill station will fill it - the last guy I know of who brought in a baked tank to be filled swore it wasn't, and the tank blew - and most folks in the tank filling business know it. So if they insist on a hydro first even though your paint job is obviously not baked, go on and bite the bullet - after all, it's their tail on the line when they're filling.
Rick
 
I need to touch up my tanks. I just got hydros and the new stamps have damaged the paint.

I want to prime the bare metal first, should i use oil or water based primer ?

Andy
 
i gess i should use the same type of paint OMS used, water based or oil based.

Does anyone know if OMS tanks come painted with oil or water based paints ?

ANDY
 
To refurbish a steel tank could you sandblast the tank and use Rustoleum cold galvanizing compound paint?
Anyone ever do it this way?

Thanks
 
I would strip it with stripper, clean it up, and paint it. I wouldn't take a chance on losing any material. You might bead blast it or something. Stripper works fine. Then put your cold galvanizing on it and paint it with some good paint. I've got one painted John Deere Green that looks pretty snappy, and a red rustoleum painted one. Actually it's quite easy. I think people obsess too much about painting tanks, just do it.

As far as cold galvanizing, FredT knows the best kind, but I can't remember. I'll write it down this time. I got some that is supposed to be "marine" but it's pretty lame.

Now that I mention it, FredT knows about everything, but don't ask him about politics. Really.

Dave
 
The OMS product (Faber) uses a two-component epoxy paint. It is my understanding that OMS sales a touch up kit, due to if this area goes un-attended it could develop external oxidation, once this starts it is difficult to stop. I would check with your local OMS dealer.
 
I occassionally dive with an OMS 98. The tank is 5 years old, never been in salt water. I have used an OMS boot on it always. I just took the tank in for a visual and learned that the coating under the boot has completely corroded away. Even though the tank hadn't been in water for 2 weeks, there was still a significant amount of water trapped there.

I sent a note to OMS a couple of weeks ago, but haven't heard back from them... don't really expect too. This tank probably only has about 50 fresh water dives on it and it appears to be toast. It is dissappointing that a company with OMS' reputation hasn't addressed this...

Has anyone else had similar problems? I generally dive twin Scubapro 95s with boots. These tanks probably have 400-500 dives on them and show no sign of corrosion.

I also use an OMS 46 for O2. I removed this boot as well and found a large amount of water there as well.

I know that boots aren't generally a great idea, but I dive from a small boat with fiberglass deck, and I want the boot to protect the boat...

I'd be interested in hearing from others who have had similar problems...

Stoo
 
OMS recently lost a lawsuit over their paint problems from 1998. I have the same problem with 2 98's but they want to charge me to repaint them so I am going to do it myself eventually or sell them and get PST tanks. I just keep touching up the bad spots and peeling the paint as it flakes off....I don't have the link to the lawsuit but it was on Mid Atlantic diver group on Yahoo. Good Luck
 
https://www.shearwater.com/products/perdix-ai/

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