Rust and steel tanks

[oxyhacker]

Globals rust inhibitor is intended to retard rust while a tank is being dried after hydro or cleaning. It has no long term rust proofing abilities, as Global will tell you.

It's a handy product for a shop which is juggling many wet tanks, but most individuals doing a few tanks at a time find it is unecessary.

Hi Jim,

My curiosity is peaked. How is it applied? Does it penetrate the steel? Does it offgas into the breathing gas? Is it commonly used to inhibit rust in scuba tanks? After reading the material safety sheet, it doesn't seem like the friendliest of chemicals.

Thanks again,
carbon

 

[jiveturkey]

I'd stick with Fabers. PSTs are nice tanks but are more prone to rusting. It's likely that once they've been tumbled once you need to tumble them every year. The Fabers are much more durable in this respect.

 

[Walter]

Unless your not keeping air in them when storing, or are completely draining them during dives........it sounds like your getting bad air.....meaning they might not be regularly changing their filters.....Just my guess with what you provided.....

It's more likely there's water (from boat spray, rinsing, etc.) on the valve that is forced into the tank when it is filled. Always blast out the water from the valves before taking them to be filled.

 

[garyfotodiver]

anual vis now you know why! steel does rust. I don't know were I read a story about someone why had a steel tank, had his own compressor, filled the tank let it sit for a month(I think) then went diving and died. The rust in his tank consumed most of the Oxygen from the fill.
In spite of that knowlege, I recently came accross a steel 72, and bought it (part of a package BC; Reg's and tank), [private sale], it's now being hydro'ed and vis'ed. I'm hoping it passes.
Safe diving to all

I'd REALLY like to hear more about this alleged incident...

 

[Nemrod]

That is an urban legend.

N

 

[garyfotodiver]

That is an urban legend.

N

My thought precisely...

 

[DennisW]

Nemrod has it right, the incident never happened.

A bit of flash rust in a tank will not hurt the tank nor the diver. Flash rust will actually prevent deeper oxidation from taking place.

As Walter said, most tanks are done in by water in the tank valve or in the whip valve. Make sure the tank monkey blows the water out of the whip before he fills your tank, make sure you blow the water out of the tank valve before you give him your tank.

 

[Jay Roy]

After a tumble , you need to re hydro to make sure the tank is ok.
Tumbleing media can remove material from the inside of the tank other than the rust.
Jim Breslin

There is no way that that tumbling a cylinder would affect the integrity..Sounds like a dive shop looking to make a few extra bucks....

 

[Hoosier]

Take care of your tanks by yourself regularly. That is only way to get over the problem.

 

[Belmont]

Flash rust will actually prevent deeper oxidation from taking place.

Wrong,

Rust is permeable to oxygen and in the presence of water iron will keep on oxydizing more and more. This is why iron eventualy disintegrate and turns to iron oxyde after time.

On the opposite, zinc and copper oxyde form a protective coating ont the base metal that make them corrosion resistant. The reason copper roofs last so long.