JeffG
Contributor
If there was moisture in the tank the damage has already been done. There is no need to drain them.in_cavediver:
Old doubles rig
- Thread starter kirkryan
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in_cavediver
Contributor
JeffG:
True, but if there is moisture and the damage has been done, then possibly the structural integrity has been somewhat compromised. If thats the case, I personally wouldn' them filled with significant pressure in it and close to me.
Of course, its judgement and opinion. Plus, unless they are in vis and hydro, you're going to pop the valves/manifold anyway.
OP
kirkryan
Guest
I'll get the pics up as soon as possible. Thanks guys!!
OP
kirkryan
Guest
Well, here are some of the numbers on the tank... 3AL DOT-E6498-3000 P170411 USD. Does this make any sense to anyone? I didn't think the pics were very clear. The other tank has the same numbers exept the P# is 170417.
JeffG
Contributor
Alum US Divers tankskirkryan:
What is the last hydro date? this would be a number followed by a symbol that I do not have on my keyboard followed by the 2 digit year. Again without opening them up you don't know what kind of shape they are in.
If I remember right, 6498 means it's made of the alloy that has a little more tendency to blow up. 6061 is the new Luxfer alloy...6351 I think was the old one. 6351 has problems with SLC, sustained load cracking. They develop cracks more readily than other alloys of aluminum. Depending on the year of the original hydro, alot of places won't hydro them even--my local hydro place won't anymore, they stopped a month ago. If you have them VIP'd, they could tell you if there were any visible cracks. If there arne't, and someone willl hydro them, get it done. Make sure to have the LDS vip them again when they come back from hydro--sometimes the older tanks will develop small cracks after being hydroed. If they are doubles though, you might could sell the bands and the manifold on scubaboard or ebay for a little bit of money regardless. Then you have two big aluminum flower pots. Or, attach pipes and you have two good baseball bats for Paul Bunyan. Get them looked at by an LDS first though, there is a small chance you could use them. I say small because it seems most places are afraid of the older tanks and won't touch them regardless (that was the answer from two out of three LDS's) The only local shop that would vip mine basically told me "this vip is only good here. no one will fill this around here except us when they look at the hydro date. it sucks, yes, but people are scared of these tanks becuase some ofthem blew up."
[edit] while the last hydro is important, so is the first hydro. The rule of thumb locally seems to be, I believe, no tanks hydroed that are older than 88. Some places are rumored to only fill tanks on the original hydro, but those places are rare. Regardless, that 6498 kills you. no pun intended. those four numbers will scare away most people.
[edit] while the last hydro is important, so is the first hydro. The rule of thumb locally seems to be, I believe, no tanks hydroed that are older than 88. Some places are rumored to only fill tanks on the original hydro, but those places are rare. Regardless, that 6498 kills you. no pun intended. those four numbers will scare away most people.
If someone will pass them and you can get someone to agree to fill them, I would still have them eddy current tested prior to filling. The pre-6061 alloy tanks are becoming (thankfully) rarer, but the EC testing is at least reassuring.
Don Burke
Contributor
E6498 means 6351 alloy and almost certainly made before 1982.
Considering how aluminum responds to fatigue, I would consider these to be scrap metal.
Considering how aluminum responds to fatigue, I would consider these to be scrap metal.
kirkryan:
pescador775
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Kirk, you have your answer. These pre-1990 aluminum tanks are probably OK but there will be an expense and general hassle factor when attempting to use them. The dive shops may be reluctant to deal with them. The required visual inspections require special equipment and will be too expensive to justify ownership. The actual value of an old aluminum tank is about $50 on EBay but shipping and other expenses would raise the cost of ownership and a knowledgable person probably would not bid.
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