old aluminum

[tfan]

Back again ! board was a big help w/ my o2 tanks (still a project)----so heres my latest for the experts.
Have an Alum last inspected in 77 and have gotten conflicting opinions on its viability-----before I get it to the lds--------heres what I have---
3AL-----------DOT-SP6498-2475--------------Z11292 USD----------3 ALCAN 72-----------6 A77------------------
So ,what do you think ?----worth the hydro/eddy ?---if it passes,does its age alone give it a shortened life,if it does pass---any reason for a shop not to fill ?---also,what do the stampings designate ?

Thanks again for the help.
tfan

 

[JahJahwarrior]

Us divers 6531 aluminum alloy. Might pass hydro, requires the eddy current test. Many shops won't fill, but probably just as many proudly fill them. Tanks are quite cheap and I don't think it's worth the risk and hassle, I wouldn't bother getting it anything except cut in half to make an umbrella stand and wind chime, but others will disagree.

 

[Jim Lapenta]

I disagree. Would also make a good visual aid for classes if cut length wise.

 

[Luis H]

With the 2475 psi pressure, that is a very early aluminum tank. They were around for one or two years (around 1972). This one looks to be from 1972. They were 72 cu ft at 2475 psi.
The most distinct characteristic is that they float like a buoy. In order to use it you need to strap at least 5 pounds to the bottom. If you don't strap at least that much weight to the bottom of the tank it will float up and tend to hit you on the back of the head.

If it is the 72 cu ft tank that that I am familiar with, they are also very tall tanks.

I can't think of a worst tank to own... I almost bought a couple in 1972... I am so glad I didn't.

 

[Scared Silly]

Is my cylinder made from the "bad" alloy aka AL6351?

 

[spectrum]

Just say no.

On top of the technical reasons cited above the hostility towards a 1972 aluminum cylinder will make it hard to get filled at best. Many shops are black balling ANY AL cylinder when it hits 20, let alone 40 years of age.

Pete

 

[Gilldiver]

As Luis said it is an aluminum 72 and was know as a "floater" due to the boyancy of the tank. But some cave divers like them for stages because of the buoyancy. As it has very little use, you should have no problem getting it past hydro but getting it filled will be a shop by shop problem.

 

[rhwestfall]

As is said above, tall, floaty, low pressure & volume, and a general PITA in the urban legend category.....My 2 "cork bottles" are waiting for (1) ambition to make a pair of wind chimes, or (2) good scrap price for aluminum.

 

[spectrum]

With the 2475 psi pressure, that is a very early aluminum tank. They were around for one or two years (around 1972). This one looks to be from 1972. They were 72 cu ft at 2475 psi.
The most distinct characteristic is that they float like a buoy. In order to use it you need to strap at least 5 pounds to the bottom. If you don't strap at least that much weight to the bottom of the tank it will float up and tend to hit you on the back of the head.

If it is the 72 cu ft tank that that I am familiar with, they are also very tall tanks.

I can't think of a worst tank to own... I almost bought a couple in 1972... I am so glad I didn't.

I has to make you wonder how the heck it even made it to market. What were they thinking? Did it take some technical breakthrough to form the proportions of today's AL 80 which is no prize either?

 

[captain]

I has to make you wonder how the heck it even made it to market. What were they thinking? Did it take some technical breakthrough to form the proportions of today's AL 80 which is no prize either?

The thought probably was to keep the diameter the same as the old steel 72 since that was what most all back packs and double bands were made for and most shops were not set up for 3000 psi service.