Tank lifetime

[Marcus]

Hey guys I was wondering if somebody can answer a question for me.

I aquired a steel tank (alum 80 equivalent) from my neighbor and I was wondering what the lifetime was on these. It looks in pretty good shape but is old. Still got air in it. It's got stickers dating back to '88.
I was wondering at what point will a dive shop refuse to fill it.

The numbers I got off of the side of it are as follows:

DOT - 3AA2250
HJ 257554
CO89
312
2C84
10 - 76

Any ideas?

[richhermes]

Go get it hydro'ed and VIP'ed. If it passes, Use it!

County Fire Equipment here in Tampa will do a hydro for $15.

[fishhunta]

it is an old lp 72, i wouldn't fill it, neither will anybody in my dive shop.

[FredT]

Originally posted by fishhunta
it is an old lp 72, i wouldn't fill it, neither will anybody in my dive shop.

Exactly WHY would you not fill a 3AA 72 with current vip and hydro?

Justification needs to be based on metalurgy and fact, not lawyer's "opinion", rumors, or misinformation spread by insurance companies to "justify" bumping rates.

Bottles of the same metallurgy manufactured before '51 are still valid and in use by industy, having recieved much heavier use than any 72 could have recieved. Industrial tanks dating back to the 20s show up occasionally and are just as servicable as new bottles if used within their design limits.

Marcus,

There is NO 'lifetime" on a steel tank. If it passes hydro and is free from internal or external pitting it's good to use. If it fails hydro or vis it should be a garden gong.

The lower working pressure means the tank ape has to have a clue and actually READ the tank like they are REQUIRED to do before filling it.

There is an OSHA training reqirement that anyone working with compressed gas bottles be trained in what the numbers mean and how to interpret them!

This is not necessarily true of alumibombs, as hydros are not as effective in culling abused aluminum bottles from the product stream.

FT

[richhermes]

Thank you Fred. I was wondering the same thing since we have a 72 too, that is probably out of hydro.

[fishhunta]

my shop will not fill them because we've had one crack at the neck during a fill, and another blow out a side and go through the roof. we're not following industry standard, just WE won't fill them. 4 tanks have gone at my shop since 1976, so we're a little careful. one dead employee, and another with half a hand will do that to ya.

[FredT]

From what I remember the one that blew and took Chris' hand was an alumibomb. I _think_ the neck crack incident was too.

FT

[Marcus]

Thanks for responding guys.

Fishhunta,

Where the 4 tanks that blew, old steel tanks? Do you know for a fact that they didn't blow because they were overfilled?
I understand your caution, but I'm trying to ascertain my own safety based on facts.

Whether or not it's safe won't do me a bit of good though if nobody will fill them.:(

[junior]

The shop I worked in used all old LP 72's for training and we probably taught as many classes as anybody in the Ft. Lauderdale area. Those tanks always passed hydro. Many of them were 20-30 years old and we filled and used them constantly. For personal use they are not sized for your BC or tank racks unless they are all you use so that is a pain in the ass.

I won't contest anyone who won't fill my tanks for whatever reason since there is always someone else right down the street who is fully willing to take my money. Shops make nothing on fills, but where I get my fills is where I typically buy the stuff that shops actually make their money on.

[richhermes]

Amen, Junior!

[ROCK BOTTOM]

I realize the original question concerned a steel tank, but what is the usable lifespan for aluminum?

[junior]

I went to a LDS recently that would not fill recently hydro'd and VIP'd tanks manufactured in 1983. It's a crap shoot...literally:D

[FredT]

Originally posted by ROCK BOTTOM
I realize the original question concerned a steel tank, but what is the usable lifespan for aluminum?

This is still up for discussion.

When originally sold they were advertized as "lifetime tanks".
They now seem to be considerably less than "lifetime" but just how much less is still a matter of dispute. Some think 10,000 fills, others are claiming 10 or 15 years. IMNSHO All these are pulling numbers out of the air as the research as NOT been done to prove any useable lifetime.

The luxfer pre-88 "bad" alloy tanks may have a .001% failure rate (or is it 0.00001%) from sustained load cracking, but one failure is REALLY bad for a dive shop. They tend to be naturally skittish about this. Then again the $s spent for their skittishness are not theirs.

I can be REALLY "concerned about safety" if it doesn't cost me any money. OTOH I can be WAY more "concerned about safety" if the $s my being "concerned about safety" costs someone else are spent at my door for replacement parts and I can make a profit on it while pointing a finger at "someone else" and claiming it's their (Luxfer/PADI's) fault.

PADI's rumored upcoming '04 rules on tank filling that will apply to all PADI insured shops need to be taken by all divers with a LARGE grain of salt if only for the reason above.

FT

[WreckDiver]

Marcus before you have it hydro'ed, take the boot off the bottom, those old 72's use to rust under the boots if it has heavy rust dont wast your money.

[bgbill]

Originally posted by fishhunta
my shop will not fill them because we've had one crack at the neck during a fill, and another blow out a side and go through the roof. we're not following industry standard, just WE won't fill them. 4 tanks have gone at my shop since 1976, so we're a little careful. one dead employee, and another with half a hand will do that to ya.

Was this the case where someone was using a forged hydro stamp?

[Kasshia]

I agree with Junior's first post. When I was living and diving in Florida I had five steel tanks in 2 different sizes and two aluminum 80's and used one dive shop for everything. Until the day he refused to fill one of my steels. All my tanks always had a current hydro and VIP. That was the day I started taking all my business to a dive shop across town.

[IyaDiver]

My group has lots of aluminum 80 tanks, ever since the sustain load cracking on the older ????? aluminum alloy, I kind of scared. I have seen one which just passed a hydro test and it has a neck to corner crack when filled. No loss of life or property but the sound of the released air was scarry. I don't want to take chances, now all 1991 or older tanks..........I throw them all away. I have seen the few accidents photo in the US, not a joke.

Since I sometime operate my own group compressor, I am the most worried. In fact after 10 years a tank is considered too old for us. Now, we sell tanks away and try to maintain a 5 years or younger tanks. The lost is only maximum US$30 a year when we sell those tanks, so the average cost per dive to us is only less than 15 cents if we keep our tanks 5 years old before selling, at the rate of our diving.

Drink less of 1 can of beer a week, it will get you exchanged for new tank in 5 years.............. :D

[BobK]

So you're saying that I have to drink 1 less beer a week, just so I can swap my tanks out every five years ? Do you understand the sacrifice you so cavalierly suggested ?
Why can't the wife give up a haircut now and then ? It just grows back again anyway, and then ther'd be none of that "give up a beer" talk going on.
Scary, the things your suggesting, Iya.

[IyaDiver]

:D :D , ok let us use the wives. Tell them to buy 1 less party shoe every 5 years....;)

[Spearchucker]

You just watch it Iya, I have been known to kill a man for less than suggesting I give up a beer!

[fishhunta]

yeah- i work at the force. the tank that took chris's hand was an aluminum, and so was the one that killed the other gent., but the other two, including the one that went through the roof were lp72's, so the owner, whether or not if i agree with it, declared that we don't fill them anymore, so i listen. i won't fill anything that i think is sketchy, i would rather lose a customer for life than blow up......they don't pay me enough for that.

[IyaDiver]

My wife used to work at a dive shop many years ago. One day they got a tank with a bad neck threading. It was filled up and the valve rocketed upwards, taking the compressor filling hose with it ....thru the roof and land in another shop roof. If an operator head was to be above the tank while looking at the pressure gauge, his head will probably fly off too. She said the sound was just like a bomb.

3,000 psi is a potential "bombing" pressure, I am very scared......:confused:

I personally think if small money can buy safety, we spend it. Just like buying insurance...:D

I was at a dive shop when they were repairing a very old compressor, it seems to have a bad safety valve. They tested the compressor to fill a tank and......KABOOM, the compressor exploded. The main crankcase cracked a part....I don't know how. The operator received minor injuries only because he was hit by only a small fragment of the cracks, the big ones flew to the sky. The compressor was tested outdoor, lucky me. He was a lucky guy, but all these experience made me very cautious with high pressure vessels/tanks. I was in the shop and I think some terrorist blew a bomb !!!