Tanks: How old is too old?

[Tracy]

My oldest scuba tank is a 1954, my oldest oxygen tank is from 1911. The oxygen bottle neck is completely full of hydro stamps all the way around.

 

[Eric Sedletzky]

ask your local dive shop... They are quite likely NOT going to fill them, regardless of what people say on the internet.

Wow, that’s a little pessimistic don’t you think?
As long as the tank has a good hydro date and a current VIP I’ve never had an issue, at any shop. Maybe shops in California are different.
It’s the current hydro stamp they look for, not the born on date.

 

[OMyMyOHellYes]

ask your local dive shop... They are quite likely NOT going to fill them, regardless of what people say on the internet.

If that's your experience, you should find a scuba shop that actually operates on KNOWLEDGE, not SUPERSTITION.

I have told ignorant shops and shop owners as much.

And because they are so deeply rooted in ignorance, avoid them like the plague. Who know what else they are shamelessly screwing up?

 

[broncobowsher]

The shops I know will fill them. The only thing that may be an issue is the "bad" aluminum allow. And I know shops that will still fill them.

 

[TrimixToo]

I have steel tanks with ICC numbers. They're fine. Even before I got my own compressor I had no issues getting them filled by the LDS or when traveling as long as hydro and VIS were current.

 

[Tim Clark Diving]

Shops on Guam won’t fill old aluminum cylinders, I think past 20 years. Is there a reason for this? Why would aluminum that passes hydro be bad just because it is 20 years old?

 

[Still Kicking]

Typically the cut off for aluminum is 1990. In 1989 and before SOME aluminum tanks were made of an alloy that ocassionally developed cracking around the neck (sustained load cracks). Telling which is which takes some technical knowledge so it is easier to decline to fill any aluminum pre 1990.

 

[broncobowsher]

Shops on Guam won’t fill old aluminum cylinders, I think past 20 years. Is there a reason for this? Why would aluminum that passes hydro be bad just because it is 20 years old?

There shop, there rules. You cannot make them do what they don't want to do. Can't forget that.

In general it comes back to some alloys of some tanks have been known to not hold up that well.

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

Hopefully, this thread will become a sticky as it is an attempt to help educate divers on cylinders that were made from the AL6351 alloy. Please do no add posts to this thread unless it is for factual information or corrections. I especially do not want discussions on what some dive shop...

scubaboard.com

What some shops have done was to throw a blanket rule out that they won't fill this bad alloy. To protect everyone involved. Or so that was the original intent. The tank monkey needed really simple instructions. Instead of teaching them what the bad alloy was and to avoid it, they just made a bigger and dumber rule. You can read hydro dates, so if it is over 20 years old, don't fill it. Started when the tanks in question were only 20 years old but instead of a cutoff date, just went with the 20 year cut off. Even worse is some shops will also use that rule on steel tanks. Never mind the banks in the back are probably all older than that.

I am sure it has helped them sell more tanks. Last I checked there isn't much profit margin on those. Maybe killing off the used tank values in the local area might sell a few more?

But in general it comes down to poor training and mis-information.

 

[boulderjohn]

I always assumed that the limit on aluminum tanks was due to the bad alloy. I assumed that when the common 20-year limit on aluminum tanks began to appear, it was meant to make sure none of the bad alloy were filled, and that people just kept the rule even when it was way more than 20 years since that the alloy was discontinued.

I was wrong.

I did an internet search and found articles from long ago that said aluminum tanks wear out and should be discontinued after [X] number of years, regardless of the alloy. I am going from memory now, and I think the shortest recommended time period was 15 years. That would have been on the oldest article I found. Newer articles suggested longer time periods.

Most of the articles came from Undercurrent magazine. What source did they cite? A dive shop in South Florida--Force E. In other words, somebody at Force E offered that opinion, and they published it world-wide. It might have been whoever was on duty the day the article's author was in there. I don't know.

Interestingly enough we had a thread on ScubaBoard a couple years ago about the Force E shop in Pompano Beach, FL refusing to fill a 20-year old aluminum tank. I went into that shop and asked, and the people there that day said they had no such policy. They would gladly fill a properly tested and inspected 20-year old aluminum tank. My take away from it is that on the day the ScubaBoard poster went for a fill, whoever was on duty that day rejected it based on a memory of a policy from many years past. That thread got a lot of views, and that shop now has its complete fill policy posted for all to see. I haven't been in it since last winter, and I don't remember it, but it does not have a 20-year limit on aluminum tanks.

Summary: Decades ago, someone at Force E in South Florida believed that aluminum scuba tanks wear out and should be discarded after a certain number of years, and someone writing for Undercurrent magazine published that as a general recommendation. That happened more than once, with different numbers of years suggested. It is likely that the recommendation, no longer believed by the shop that originated it, was picked up by some shops around the world, and in some places the policy is still in effect.

 

[Eric Sedletzky]

Typically the cut off for aluminum is 1990. In 1989 and before SOME aluminum tanks were made of an alloy that ocassionally developed cracking around the neck (sustained load cracks). Telling which is which takes some technical knowledge so it is easier to decline to fill any aluminum pre 1990.

Luxfer’s 1989 and older were the bad ones, Catalina’s were fine.
They use a 1990 cut off just to be safe.