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ScubaCaveman
11-23-2009, 11:20
I was given an aluminum tank. It appears it is from the mid-80's. Is it even worth getting it looked at? What is the shelf life for an aluminum tank? I have no idea how long it has been sitting, etc.

ScubaToys Larry
11-23-2009, 11:31
Depends....

If they are Catalina tanks -you are good to go... just get your hydro and vis...

If Dacor, Luxfer, or a host of other names (made by luxfer) then they would be made from the 6351 aluminum that many shops will not fill.

So do a search on 6351 here, and you will see a lot of opposing thoughts - so it's up to you and the place you get them filled if they are worth having or not.

ScubaCaveman
11-23-2009, 11:36
How do I tell what kind of tank it is? Is that stamped into it somewhere?

ScubaToys Larry
11-23-2009, 11:49
Yes - around the neck are lots of numbers and letters and symbols. Do you see a SP6498 or E6498 stamped in there?? The word Catalina?

A good close up picture of the markings at the top and we could tell you what you have there...

WD8CDH
11-23-2009, 13:34
Aluminum tanks don't really have a "shelf life" but if it was made from 6351 alloy, it's not worth the hassle. The valve is probably useful.

ScubaCaveman
11-23-2009, 13:54
It is stamped SP6498. What does that mean? Is it good?

The last visual was done June 1984....

Rileybri
11-23-2009, 14:13
It is stamped SP6498. What does that mean? Is it good?

The last visual was done June 1984....

Although cylinder identification "should" have been covered in OW class, this LINK (http://www.underwaterdivingequipment.com/tank-markings.html) should help you figure out what kind of tank you are dealing with. There is a TUN of info on ST forums about this subject......

Hope this helps.....

WD8CDH
11-23-2009, 14:35
It is stamped SP6498. What does that mean? Is it good?

The last visual was done June 1984....

Unless it was made by Catalina, that is not good. Up until ~1988 Luxfer and most other aluminum tanks were made from 6351 alloy.

FishFood
11-23-2009, 15:29
Take it to your LDS, or where ever you plan on filling it, and let them tell you If it's good or not. Ultimatly they will have the final word on filling it, and shop policies seem to vary widely.

For example, 6351's aren't difficult to get filled around here... But then again, these people don't blink at shoving 3500+ pounds of air in a low pressure tank... :D

Lone Frogman
11-23-2009, 15:40
The fact is many dive shops will not fill aluminum tanks older than 20 years. Doesn't matter to them what the alloy.

ScubaToys Larry
11-23-2009, 16:11
It is stamped SP6498. What does that mean? Is it good?

The last visual was done June 1984....

No.. That's the "bad" ones... I'd tell you don't mess with it... others will have a different opinion.

This is one of those tanks that exploded... http://biobug.org/scuba/scubatank/scubatank_files/image017.jpg

navyhmc
11-23-2009, 16:37
"Yeoch"!!!!

scubajane
11-23-2009, 16:43
way to go Larry!!! Just saved another life!!!! Thanks

Rileybri
11-23-2009, 16:51
It is stamped SP6498. What does that mean? Is it good?

The last visual was done June 1984....

No.. That's the "bad" ones... I'd tell you don't mess with it... others will have a different opinion.

This is one of those tanks that exploded... http://biobug.org/scuba/scubatank/scubatank_files/image017.jpg

And I bet he has a good deal to give you on a new tank as well!

ScubaToys Larry
11-23-2009, 17:34
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FishFood
11-23-2009, 18:07
On the flip side - Evidence supports that neck cracks take years to develop before becoming a failure point. A yearly VIP and eddy current test is more than sufficient to make sure a 6351 tank is safe. Furthermore, one must bring the tank failure rate into perspective. Approx 20 cylinders world wide have failed... out of over 25 million.

The real problem, however is that many dive shop VIP's are not properly performed. It's more than spinning the valve off, peaking inside, and replacing the valve... But that's what many shops do.

Anyhow, again, talk to the person that will be filling the tank. It's 100% up to that person.

Besides, Larry carries the SHINY tanks. Hard to resist ;)

ScubaToys Larry
11-23-2009, 18:32
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Uh... sorry about that. My dogs jumped up on the table and decided to post... Not sure what that means... but it must be important to the discussion! :smiley29:

http://www.scubatoys.com/images/computerdog.jpg

FishFood
11-23-2009, 18:33
I read it to mean 'discounts on new aluminum tanks' :dunno::fulle:

ScubaToys Larry
11-23-2009, 18:45
Furthermore, one must bring the tank failure rate into perspective. Approx 20 cylinders world wide have failed... out of over 25 million.


I've had this argument happen several times... Just wanted to give you a slightly different twist on your stats. You looking at about 10 tanks blew up (failed sounds so tame) in the US. Let's not look at how many tanks were manufactured, as we both know, a lot of these were condemned, traded in in the old trade in program they had, scrapped, or sitting in a basement waiting to be given away, as in this case.

So let's look at the numbers a bit differently. There are about 2000 shops and fill places in the US. Now about half the shops don't fill these tanks.. so that means about 1000 shops with 10 tanks blowing up... so now the stats say if my shop fills these, I have about a 1 in 100 chance of blowing up my shop, one or more of my employees and perhaps a customer or two... to make under 50 cents profit on a fill after maintenance, labor, and amortization of the equipment.

So we decided not to fill those tanks at our shop... And yes, you might make the case that if they are properly tested, there is no danger - but years ago, I personally did a VIP Plus test on a tank with a very bad crack that already had a current VIP Plus sticker. Did the other people do a bad test?? Did the tank rapidly go bad?? Did it never get tested and someone just bought a sticker on the internet to slap on it?? Don't know - but it was on that day, I decided, we would no longer fill the 6351 tanks no matter what sticker they had on them.

For a tank that costs 150 bucks 20+ years ago, you can say this tank depreciates less per year than a single fill costs - so for safety sake - say it's had a good life and turn it into a beautiful planter.

scubadiver888
11-23-2009, 20:07
Very well put Larry. By the way, cut the top off, put a boot on the top piece and it makes a good base to a table lamp.

Smashee
11-23-2009, 20:28
. By the way, cut the top off, put a boot on the top piece and it makes a good base to a table lamp.

Add a length of chain and some concrete to it and you'll have a brilliant shot-line weight.

ScubaCaveman
11-24-2009, 06:14
It is stamped SP6498. What does that mean? Is it good?

The last visual was done June 1984....

No.. That's the "bad" ones... I'd tell you don't mess with it... others will have a different opinion.

This is one of those tanks that exploded...

Thanks Larry! I guess I will be seeing what the local scrap yard wants to give me for it. Unless anybody here wants it. Need to pick it up though.

ScubaToys Larry
11-24-2009, 08:05
Tank weighs about 30 lbs, and I believe aluminum scrap is right about 50 cents a pound.... so it's about 15 bucks you got there..

ScubaCaveman
11-24-2009, 09:17
Tank weighs about 30 lbs, and I believe aluminum scrap is right about 50 cents a pound.... so it's about 15 bucks you got there..

Whoa 15 bucks!! Sweet thats a good 12 pack for me! Perfect for the Holiday weekend.