Coating inside of tanks

[Tidoubleger24]

Hello,
this may sound crazy but..... i was just wondering what the regulations of painting the inside of a tank to prevent rust from ever forming. The paint is a special coating that gets harder with exposure to moisture and prevents moisture from reaching the painted surface, ie the tank. You can check it out at http://www.por15.com/product.asp?productid=6 The paint also flexes with the metal, so that when the tank is hot filled or hydrotested, and it expands, the paint wount flake off. You can hit the paint with a hammer without it coming off the surface, as ive done it. Once the paint cures it doesnt give off fumes, but i dont know about regulations.... I know with proper care, a tank wount be exposed to moisture, but my tank was over $300, and any protection that i can give it, is more than worth it to me. any thoughts?

 

[jonnythan]

If I were you, I'd want to keep anything that might possibly dissolve into the air or provide gasses in any way *out* of my tank.

 

[captain]

Back in the 70's an epoxy coating was tried without success.
It was impossible to get a coating that did not have some porosity that allowed moisture to get under it. Also the constant expansion and contraction from full to empty and hot to cold caused the coating to fail. Most of the time the coating was tumbled off at the first hydro to get a better look at the metal.
Your LDS may not be willing to hydro it with a do it your self coating. Also if the coating starts to flake off peices could in up in your regulator. All in all its not a good idea.

Captain

 

[ScubaRon]

I hope this question is not serious, but just in case it is:
- This product is not designed for the extreme temperatures and pressures inside scuba tanks.
- Proper application is just about impossible. Any "drips" are likely to come off and may cause your regulator to clog up.
- I hate to think how this product will react with oxygen when using Nitrox.
- No dive center will knowingly fill a tank that is coated.

Why are you concerned about rust: if you keep your tank under pressure and use good quality air it won't rust.
So: don't!
ScubaRon

 

[DA Aquamaster]

I have 4 steel 72's from the late 60's and after 35 years they are still in very good shape inside and out. I have used them heavily since the early 80's when I bought them. In my experience, a steel tank may need tumbled every 10 to 15 to remove the minor flash rust that accumulates but this is not a issue for concern. If you are using good quality air that is appropriately dry, you will not have a problem and should be able to expect at least 40 years of service out of a steel tank as long as you do not routinely overfill it, do not get water in it, or store the tank empty with the valve off or open.

I have seen steel welding tanks made prior to WWI that are still in use and still pass VIP's and hydros. A properly cared for steel tank has an exceptionally long service life - far longer than aluminum.

 

[pescador775]

The good news is that you can buy tanks with effective internal coatings. Faber and re-marked Faber distributors sell tanks with iron phosphate or manganese phosphate coatings. The bad news is that the EXTERNAL coatings are not so good.

 

[pdoege]

If the coatings are not clear and/or metallic the inspector will have to remove them in order to examine the metal beneath.

If he/she can't remove the coating, he is going to have to decline to return the tank to service.

I would avoid all internal coatings that do not come from the factory.

Peter