How much rust is allowable on old steel tanks prior to tumbling?

[Ed Palma]

Oh, just as an aside: what's a good tank supposed to sound like when you tap it? It dawned on me that the percussion note would be different around the shoulder due to thicker material, but what about around the rest of the body?

 

[Creed]

Clean it up, you might very well have a keeper. I am a PSI cylinder inspector. A lot of old steel tanks are being discarded for no good reason. I would rather dive one than listen to a wind chime.

Amen. Those particular ones look bad, but, then, I've had tanks that I thought were shot that passed a hydro and vis with no problems. Build yourself a tumbler. It's cheap, and will be worth having around even if these tanks are scrapped. At least clean them up good before condemning them.

 

[k4man]

how about NO RUST....unless you plan to breathe the stuff...I agree. Not safe for diving, but it may have some other cool uses!

Kevin

 

[Creed]

how about NO RUST....unless you plan to breathe the stuff...I agree. Not safe for diving, but it may have some other cool uses!

Kevin

A tumbled tank is perfectly safe for diving. All of my 72s were tumbled. They have had 0 problems in all of the years I've had them. Flash rust is a fact of life. No offence meant, but trashing a tank because of rust that doesn't affect the structural integrity of the tank is foolish. And the only way for a layman to know if it's a problem or not is to have the tank tumbled and tested.
On the other hand, perhaps we should encourage this thinking. More tanks for those of us who don't feel like buying aluminum tanks with poor bouyancy characteristics. A well maintained steel tank will likely outlive several generations of owners.

 

[rjack321]

Oh, just as an aside: what's a good tank supposed to sound like when you tap it? It dawned on me that the percussion note would be different around the shoulder due to thicker material, but what about around the rest of the body?

Should ring with a bell tone, not a clunk. Shoulder or sidewall have different pitches but still ring not thud.

 

[Ed Palma]

Hmmm, a bell note...gawrsh.
And in spite of this fact, ever optimistic me, knowing fully well the dull thud that came off from the tank, will still try to inspect it and get them tested...

 

[Ed Palma]

So I went and did it, got the 2nd tank. when I tipped over the tank, water came out of the boot. I took it off, expecting the worst, but so far just a few pits near the bottom. I sanded down the flaky finish, revealing most of the markings. Internally, its all dark inside, but no outright flakes have come from it upon tipping over. I'll get it tumbled and hydroed.

From the markings, I have thus ascertained it to be a scubapro 15.0L tank rated to 200 bar. I'm assuming the 9s90 on the neck is the last hydro it underwent.
Any other information regarding the other markings would be welcome. At any rate, the lettering was still deeper than that major rusty part on the shoulder.

The old J-valve was actually still functional, because when I started loosening the reserve handle, a slight hiss could be heard at least I think I did).

It makes a nice ringing sound when tapped, but I've still got an iffy feeling about the thing though...

Just in case, is it okay to underfill it? Just to increase the safety margin?

Ah well, its nice to know the history of this probable $29 wind chime

 

[Creed]

Just in case, is it okay to underfill it? Just to increase the safety margin?

If it passes hydro and vis, I wouldn't worry about it. If it doesn't, then it's a windchime anyway.