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

[Ed Palma]

Ahhh, what has this forum done to me?

After reading all the pros and cons of AL vs steel, I decided to look around in my area for some steel 72s. Unfortunately, most of the shops here only sold aluminum tanks. While bringing some scrap metal to the local junk shop, I noticed some tanks being sold. Old steel tanks with J valves. left open, no pressure in them. Unfortunately it seems that they would also fail an external inspection. The one tank that looked promising had an area with some major rust flaking! Tapping the tank produced some ping (not that resonant, but around the shoulder, it was rather dull.

This is the one with the severe flaking...

This is the one I thought had potential...

but...

Interestingly though, it was stamped 200BAR on the shoulder.

Are these tanks dead in the water?

If they are, pity, because I don't think I'd like to do aluminum anymore.

 

[fishb0y]

Stick a fork in them...

 

[Ed Palma]

*sigh*

 

[rcontrera]

Doyourself a favor and strip the junk off of them and get them sand blasted. that will give you a true indication of the condition. If they still aren't up to snuff, cut the bottom off, sand blast the inside, coat with verathane (sp?) and make bells out of them. VERY COOL SOUND!!

 

[Ed Palma]

you mean they actually might have a chance? I think now I'll lean more toward the scubapro tank. although extensive in area, the depth wasn't that bad. Plus the neck of the other tank seems to have a chip in the picture. I'll just have to go back and check some more, maybe take a peek inside.

 

[DA Aquamaster]

On the inside any flash rust that accumulates ot the point that it may obsuce a pit needs to be removed. In other words... if you cannot do a thorough cisual inspection due to the rust it needs to be removed so that you can properly inspect the tank and ensure no pits are present.

Externally, any pitting in the shoulder needs to be less than or equal to the depth of the letters and numbers stamped in the shoulder. On the sides, due to the thinner wall thickness there, you should be a lot pickier and anything other than very minor sand grain sized or smaller pitting would be cause for condemning the tank.

Flaking, deep pits or extensive pitting is pretty much an indicator that you own a wind chime.

 

[Creed]

If nothing else, salvage the valves. They'll be brass, and likely functional.
I bought a 72 that was pretty rusty looking. I figured that it was junk. Upon tumbling it, and cleaning up the neck threads with a wire wheel on a dremel, it passed hydro and vip with flying colors.
Build yourself a tumbler. There are lots of plans for them on the web. I personally use a mix of sand, small rocks and shells, and spent cartridge brass from .22 bullets as my tumbling media. It will grind rust and gunk out in short order without gouging the steel.

 

[rjack321]

If nothing else, salvage the valves. They'll be brass, and likely functional.
I bought a 72 that was pretty rusty looking. I figured that it was junk. Upon tumbling it, and cleaning up the neck threads with a wire wheel on a dremel, it passed hydro and vip with flying colors.
Build yourself a tumbler. There are lots of plans for them on the web. I personally use a mix of sand, small rocks and shells, and spent cartridge brass from .22 bullets as my tumbling media. It will grind rust and gunk out in short order without gouging the steel.

Those valves may function, but you'll have a bugger of a time finding parts for them.

Its hard to tell about the cylinder with the net over it, but non-galvanized steel tanks of this vintage should just go bye-bye. They aren't worth it. Bead blasting most of those shown looks more expensive than their value. You should be able to find some better looking ones (not requiring tumbling and bead blasting which all costs time and money) for $40 to $70.

 

[Ed Palma]

Thanks for the replies, guys.

I think part of what I'm looking for is a project to do in my spare time

Barring possible costs (and nope, no J valve parts around here!) I was just wondering if these puppies could be whipped into shape.

Anyway, I'll be returning to the shop tomorrow and will strip the net and boots off, as well as take a gander into the tanks themselves, see what I can see.

Will update as I go along.

 

[james croft]

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.