Tank Age Anxiety

[scubaguy532]

Hi everyone. I am a somewhat newer diver and have been doing more shore diving recently so I went ahead and purchased 2 used aluminum 80 tanks. They have both passed their hydrostatic test within the last 6 months and are both well within their yearly visual inspection period. Additionally they were both filled with air (nitrox) when I bought them. However they are older tanks, one of them is a Catalina with the first hydro test in 1993 and the other a Luxfer manufactured in 1990.

I've been assured that the age shouldn't matter as they are both in good condition and have been recently inspected but I can't help but feel somewhat anxious about using 30 year old tanks. Additionally they aren't due for the next hydro test for another 4 years so is there a chance of anything going wrong before that time? Essentially are my concerns valid or am I just worrying too much?

 

[DiveGearExpress]

Any SCUBA cylinder that has passed a current hydro test (every 60 months in the US) and visual inspection (annually in the US) by qualified inspector is suitable for use without concern related to total age.

Your cylinders are made with an aluminum alloy called 6061. There are some concerns about a different specific 6351 aluminum alloy that was used in the Luxfer S80 cylinders manufactured prior to 1988. However, since your Luxfer cylinder was manufactured in 1990 it is not made with 6351 alloy and Catalina never used the 6351 alloy, this issue is unrelated to your cylinders.

 

[inquis]

Age itself is meaningless. Ask yourself what is making you anxious? Is it, for example, a fear the material has become brittle? If so, the hydro should allay that fear. If it doesn't, then perhaps get another hydro for your peace of mind.

 

[James79]

Essentially are my concerns valid or am I just worrying too much?

Dive gear express addressed the one real issue with old aluminum tanks (the bad alloy era). I don't dive aluminum, but I do have steels as old as 1944.... Simply put the hydro test is there to catch weakening before it can be a safety issue. When they hydro'd the tanks, the filled with water and pumped it to 5000 psi (5/3 working pressure). Then they check how much it stretches, and how much it snaps back after pressure is released. And pass/fail off of strict criteria.... So a failed hydro isn't ready to burst, it just didn't have the safety margins it should anymore. And your tanks passed (therefore still have huge safety margins).
TLDR- worrying too much. If hydro and vis are current, dive them!

Respectfully,

James

 

[kelemvor]

Not only are you over thinking this, but you're missing something important.

Diving older slightly beat-up gear can be a sign that you're not a complete noob. Gear (especially tanks) gets beat up very quickly if it's actually getting used - hence the correlation.

Obviously there are exceptions, as with everything in life. My point is simply that older gear can be a boon.

 

[scubaguy532]

Age itself is meaningless. Ask yourself what is making you anxious? Is it, for example, a fear the material has become brittle? If so, the hydro should allay that fear. If it doesn't, then perhaps get another hydro for your peace of mind.

I think the main thing that concerned me is I recall reading on a couple of sites that the average lifespan for aluminum tanks is 20 years. But then again it probably depends on use and care quite a bit.

 

[Lorenzoid]

As a practical matter, whether a dive shop will fill your tanks--or any tanks--is within their discretion. A dive shop could hassle you with some goofy rule of theirs that they don't fill tanks (or perhaps just don't fill aluminum tanks) older than X years, regardless their passing hydro and vis requirements. I have no idea how common it is for dive shops to have such a rule.

 

[boulderjohn]

First, your tanks should be just fine.

But...

You may find well meaning people who will tell you they are not fine. Some shops will not fill tanks that old because they don't know any better.

DiveGearExpress accurately pointed out the alloy issue, and I used to think concern over that was the reason some shops refused to fill older aluminum cylinders. A recent thread on this changed my mind. An Internet search led me to past articles, some surprisingly recent, that proclaimed a short life expectancy for all aluminum cylinders. I found one saying you should get rid of cylinders older than 15 years and several saying 20 years. Those articles are all outdated and should be ignored, but you could easily run into someone who learned from them and has not subsequently learned that those policies are obsolete.

 

[Jim Lapenta]

I've run into several shops that have a 20 yr cut off for aluminum cylinders and even one that refused to fill a person's STEEL 72's that had passed hydro and were from the 70s. Age was the ignorance based reason.
I have heard of one hydro place that decided to stop doing older aluminums because they were getting all kinds of grief after passing a cylinder that some shops decided not to fill.
If it has a current hydro and vis we fill them.
6351 alloys the owner has decided not to and he owns the compressor.

 

[inquis]

So a failed hydro isn't ready to burst, it just didn't have the safety margins it should anymore. And your tanks passed (therefore still have huge safety margins).

OP, I think this is your bottom line. Consider it a victory if you can dive so much that you eventually have a hydro fail.