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Scuba Forum / General / October 2007Are Old Tanks Worth Hydroing?
I have a couple old tanks from the 1980s. One is an aluminum 80 and the other a steel 72. I've just returned to diving from a long absence and stopped in at a couple shops to look at gear. While there I asked about hydroing the tanks. One told me $25 each and the other told me $35 for any tank manufactured after 1991 and $5 for pre-91 tanks. They said this was because DOT has changed the standards on pre-91 tanks and is likely to prohibit their use in the near future. Does this make sense or are they just trying to sell me new tanks? Thanks.  SignatureToo many spams have forced me to alter my email. If you wish to email me directly please send messages to pjbphd at cox dot net > I have a couple old tanks from the 1980s. One is an aluminum 80 and the > other a steel 72. I've just returned to diving from a long absence and [quoted text clipped - 7 lines] > > Thanks. They are trying to sell you new tanks (which is not a bad idea) and with the aluminum tanks, might not be doing you a disservice. Take them to a local fire supply place, or find out where the hydro's are done, and take them there yourself. Depending on whether you do it through the LDS or a reputable hydro facility, both tanks may either pass or fail Usually the old 72's pass. Should have said "One told me $25 each and the other told me $35 for any tank manufactured after 1991 and $45 for pre-91 tanks..." >I have a couple old tanks from the 1980s. One is an aluminum 80 and the >other a steel 72. I've just returned to diving from a long absence and [quoted text clipped - 7 lines] > > Thanks. In rec.scuba, on Tue 11 Sep 2007 09:49:03p, "pjbphd" <pjbphdspamsux@cox.net> wrote: > Should have said "One told me $25 each and the other told me $35 for > any tank manufactured after 1991 and $45 for pre-91 tanks..." Bend over, grab your ankles -- they're not using any lube either. As Scott mentioned, take it to your local fire extinguisher supply store and they can do the hydro. You'll want to check around a bit to ensure that you're not taking it to a store that will just send it off elsewhere. Depending upon the manufacturer and alloy of the aluminum tank, you might want to retire it, but the steel 72 cu-ft tank is most likely still good. I have steel tanks that are nearly 40 years old and the still pass hydro and their yearly inspection. Not only that, but they've never even been tumbled. Treat them nice and don't let any water get into the tanks and they'll last a LONG time. I'll add to what others have said with a slightly different twist: - If the aluminum tank is anything other than a Catalina, drill a hole in it and recycle the aluminum. Prior to 1988, a number of aluminum tanks, including Luxfer and Kidde, were made of an inferior alloy. Several have failed explosively in the last few years. Catalina never used that alloy. If the tanks are Catalinas, they're probably about as good today as they were back then. - Steel tanks tend to last longer, but are vulnerable to rust. Take the valve off and shine a small flashlight into the tank. If you see scales of rust, pits or any similar indications that the inside of the tank is damaged, drill a hole in the tank and start over. There's no point in paying good money to test a tank you already know won't pass. If it's smooth inside, have it hydro tested. Lee > I'll add to what others have said with a slightly different twist: > [quoted text clipped - 13 lines] > > Lee All true, but check the outside, too, especially under the lip of the boot and under the paint if the Al 80 is painted. For some reason, divers who will take their regs, BCs, and booties in for annual service won't bother to maintain their tanks. Maybe because it doesn't cost anything to do so. If they've been properly maintained, they should be good for about 10,000 cycles. esg > - Steel tanks tend to last longer, but are vulnerable to rust. Take the > valve off and shine a small flashlight into the tank. If you see scales of > rust, pits or any similar indications that the inside of the tank is > damaged, drill a hole in the tank and start over. There's no point in paying > good money to test a tank you already know won't pass. If it's smooth > inside, have it hydro tested. What's wrong with getting it tumbled to remove the rust? >> - Steel tanks tend to last longer, but are vulnerable to rust. Take the >> valve off and shine a small flashlight into the tank. If you see scales of [quoted text clipped - 4 lines] > > What's wrong with getting it tumbled to remove the rust? Everytime you do it reduces the wall thickness and reduces strength? > > What's wrong with getting it tumbled to remove the rust? > > Everytime you do it reduces the wall thickness and reduces strength? And a lot can depend on how the tank was stored. Upright can be Ok, but if it was stored laying down, then you can get a "rust line" on the bottom that takes a lot of tumbling to dig it all out, which results in significant wall thinning. -hh >> > What's wrong with getting it tumbled to remove the rust? >> >> Everytime you do it reduces the wall thickness and reduces strength? > And a lot can depend on how the tank was stored. Upright can be Ok, > but if it was stored laying down, then you can get a "rust line" on > the bottom that takes a lot of tumbling to dig it all out, which > results in significant wall thinning. I was pretty specific about the conditions that would lead to scrapping the tank. It included significant flaking and pitting, either of which are likely to fail the tank on the next visual, with or without a hydro. Even if the tank might make it one more time, the cost benefit of tumbling a steel tank that old is limited and the risk of depending on such a tank for the five years until the next hydro date is higher than I'd choose to take. Lee > I was pretty specific about the conditions that would lead to scrapping the > tank. It included significant flaking and pitting, either of which are > likely to fail the tank on the next visual, with or without a hydro. Even if > the tank might make it one more time, the cost benefit of tumbling a steel > tank that old is limited and the risk of depending on such a tank for the > five years until the next hydro date is higher than I'd choose to take. It's my understanding that only aluminum tanks fail catastrophically, and even then it usually fails when filling and is therefore more a worry for the dive shop than the diver. If the tank passes the rigors of a hydro test, it's pretty much guaranteed to withstand another 5 years of mere air fills. Tumbling only costs $15-20, a fraction of the cost of a new steel tank. Even at $20, that's only $4 per year. If you tumble and the tank fails hydro, you're out a lousy $20 at most (plus the cost of the hydro). Risking a potential loss of $20 versus having the use of a steel tank for the next 5 years at a prorated additional cost of only $4 a year is definitely a risk I'd be willing to take. Obviously we all have different risk thresholds. > It's my understanding that only aluminum tanks fail catastrophically, > and even then it usually fails when filling and is therefore more a This is wrong, steel tanks do fail, you just dont hear as much about it. > worry for the dive shop than the diver. If the tank passes the rigors > of a hydro test, it's pretty much guaranteed to withstand another 5 > years of mere air fills. Tumbling only costs $15-20, a fraction of There are cases where tanks have passed hdyro with neck cracks, only to explode later when the fill station operator goes to fill it. A hydro does not guaruntee there are no cracks in the neck. > >> - Steel tanks tend to last longer, but are vulnerable to rust. Take the > >> valve off and shine a small flashlight into the tank. If you see scales of [quoted text clipped - 6 lines] > > > Everytime you do it reduces the wall thickness and reduces strength? Sure, you leave it run for a decade. > > >> - Steel tanks tend to last longer, but are vulnerable to rust. Take the > > >> valve off and shine a small flashlight into the tank. If you see scales [quoted text clipped - 10 lines] > > Sure, you leave it run for a decade. Thanks. That's what I was wondering. After all, if the tank is tumbled to get rid of the rust, and it then passes hydro and a visual inspection, what's the worry? I think my local shop charged me $15 or $20 for a tumbling the last time, which wasn't much in the scheme of things after the tank passed hydro and earned me another 5 years of usage. >>>>>- Steel tanks tend to last longer, but are vulnerable to rust. Take the >>>>>valve off and shine a small flashlight into the tank. If you see scales [quoted text clipped - 21 lines] > things after the tank passed hydro and earned me another 5 years of > usage. Tumbling gets rid of the dust, superficial scale, and cockroach eggs. If the tank is actually pitted, you've got a permanent problem. esg >>>>>>- Steel tanks tend to last longer, but are vulnerable to rust. Take the >>>>>>valve off and shine a small flashlight into the tank. If you see scales [quoted text clipped - 24 lines] >Tumbling gets rid of the dust, superficial scale, and cockroach eggs. If >the tank is actually pitted, you've got a permanent problem. When does scale and minor rust become pitting? JF >>Tumbling gets rid of the dust, superficial scale, and cockroach eggs. If >>the tank is actually pitted, you've got a permanent problem. > > When does scale and minor rust become pitting? > > JF On the outside, when the galvanized layer is penetrated. But to be honest, I don't know if the inside of a steel tank is galvanized or not. Scott????????????? BTW, I have a tank with serious boot rot (bought it that way) and I'm always amazed it passes hydro. esg >>>Tumbling gets rid of the dust, superficial scale, and cockroach eggs. If >>>the tank is actually pitted, you've got a permanent problem. [quoted text clipped - 12 lines] >BTW, I have a tank with serious boot rot (bought it that way) and I'm >always amazed it passes hydro. I have one just like yours. That's why I asked. It's passed inspections at two different shops and has gone through 2 hydroes since I had it given to me (free). I put together a pair of old 72's as a doubles kit and used the rig almost exclusively for a couple of summers so it had fills at more than a few different stations with no problems at all. JF > On the outside, when the galvanized layer is penetrated. > But to be honest, I don't know if the inside of a steel tank is [quoted text clipped - 6 lines] > > esg Steel tanks are not galvanized inside. Once upon a time back in the before times, some distributors tried painting the inside with epoxy to prevent the moisture from bad fills (a normal occurrence in the early times) from coming in contact with the steel. Unfortunately, they forgot that filling a tank expands it ... stretching the painted surface and creating tiny fissures that moisture could get through. When, or I should say "if" getting inspected, the paint would hide corrosion until it was so bad that the paint bubbled off. We used to tap around the inside of every one of them with a metal rod to see if anything chipped off. If it did, we insisted on having the tank stripped before we filled it. NASTY PROCESS!! Basically it was tumbling with paint stripper and then a series of neutralizing rinses and washes. After that, the tanks were better than new. My wife still has a vinyl coated tank from the 60s that we stripped out the inside. It looks like a show room new cylinder except for all the hydro marks. A lot of galvanized cylinders can start to look terrible ... especially from those old smooth bottom tank boots that trap water next to the surface. But a bunch of that is a heavy buildup of salt. I dunno what the chemical reaction is, but the zinc seems to be like a magnet to salt and other minerals in the water and buildup gets nasty!! After a few hundred dives in salt water, you can scrape off a ton of buildup before you get down to the metal. Oh ... and there are a bunch of dive shops that refuse to learn anything about scuba tanks and may refuse to fill older aluminum. Ask them for a reason for their decision and you will usually get a bunch of BS. If you do, find another shop. There are some hazardous old tanks out there but not all of them. Just my $.02 SignatureRay Contreras =-=-=-=-=-=-=-=-=-=-=-=-=-=- Webmonkey for: http://www.ossystems.com http://www.bobs-garage.com http://www.coltri-usa.com http://www.rayzplace.com > > On the outside, when the galvanized layer is penetrated. > > But to be honest, I don't know if the inside of a steel tank is [quoted text clipped - 38 lines] > > Just my $.02 Remember the liners? Like a condom <cough> for the inside of tanks. >>> Tumbling gets rid of the dust, superficial scale, and cockroach eggs. >>> If the tank is actually pitted, you've got a permanent problem. [quoted text clipped - 7 lines] > But to be honest, I don't know if the inside of a steel tank is > galvanized or not. No. Verboten. They say they cannot detect wether the layer has hollow spots under which corrosion creeps. Matthias > When does scale and minor rust become pitting? When it leaves pits in the surface of the metal. > On the outside, when the galvanized layer is penetrated. > > But to be honest, I don't know if the inside of a steel tank is > galvanized or not. > > Scott????????????? Not. Zinc is not to be allowed into your airway, at least not in modern times. > BTW, I have a tank with serious boot rot (bought it that way) and I'm > always amazed it passes hydro. Hydro is a simple test of elasticity. >>On the outside, when the galvanized layer is penetrated. >> [quoted text clipped - 11 lines] > > Hydro is a simple test of elasticity. True, but Fill Express has a tank there that was supposedly condemned by HydroTech for exterior pitting. That's their story, anyway. esg >>> - Steel tanks tend to last longer, but are vulnerable to rust. Take the >>> valve off and shine a small flashlight into the tank. If you see [quoted text clipped - 8 lines] >> > Everytime you do it reduces the wall thickness and reduces strength? Not relevant. There is a minimum wall thickness which can be measured with an ultrasound thickness meter. Matthias This is a no-brainer. Just go get them tested. I'm dropping off a tank to be hydrotested tomorrow. It's going to cost a whopping (USD) $16.50. It will cost more to get it O2 cleaned afterward. A new AL80 costs between $150-180 depending on where you get it. A new steel tank (Faber HP100) costs around $300-350. Even for an AL80, why wouldn't you just drop off the tank and see what happens? If there's a safety problem with the tank, the tester should let you know by condemning the tank. The odds are in your favor unless the tanks was stored with water in them or with the valves open. My 6351-alloy AL72, which I purchased new in 1972, passed hydro 3 years ago without incident. (It gets an eddy current test *every* year without fail but is OK so far. I might retire it soon nonetheless.) The LDS sends out a few every week and gets back a condemned tank or two a year. And some people are diving steel 72's that were made before I could walk... SignatureJohn Eells > I have a couple old tanks from the 1980s. One is an aluminum 80 and the > other a steel 72. I've just returned to diving from a long absence and [quoted text clipped - 7 lines] > > Thanks. Steel tanks rarely go bad unless they are seriously abused. Assuming you didn't store water in it, get it cleaned (tumbled), get a valve overhaul (including a new burst disc) and a hydro. Steel tanks are expensive and really are worth saving. As far as the aluminum, hydro stations are now required to do an extra test on the tanks that have been giving our little industry fits. So you may have to pay a little extra for the hydro service since most shops just pack them off to the local fire extinguisher or welding supply and are going to have to pay the extra themselves. There is one shop in Florida I know of that is doing it's own buyback on the "exemption" tanks basically for their cost. They are doing this because of a tank that cracked while being filled ... even though it had been hydro-ed and inspected a couple of weeks before. I think their deal is something like trade in your tank plus something like $90 and get a new tank. Of course, you still keep your old valve. Then they haul them to the scrap yard. See if you can find someone that will do something similar with yours. If you can't, I think the going rate is about $15 at the scrap yard. Just my $.02 SignatureRay Contreras =-=-=-=-=-=-=-=-=-=-=-=-=-=- Webmonkey for: http://www.ossystems.com http://www.bobs-garage.com http://www.coltri-usa.com http://www.rayzplace.com Many shops now won't fill an AL past 15 to 20 years old. I have a couple 79's in my garage that I use an "equalizer" to put 1/2 the left over air from my dives in.... then I use it to fill tires and pool toys. (any tank can handle 500 PSI or so... ) BTW... yes I do inspect it on occaision. >> I have a couple old tanks from the 1980s. One is an aluminum 80 and >> the other a steel 72. I've just returned to diving from a long [quoted text clipped - 31 lines] > > Just my $.02 fyi, I did have them both hydroed and VIPed and they passed with no problems. I'm now good until 2012! pjb >I have a couple old tanks from the 1980s. One is an aluminum 80 and the >other a steel 72. I've just returned to diving from a long absence and [quoted text clipped - 7 lines] > > Thanks. > fyi, > > I did have them both hydroed and VIPed and they passed with no problems. > I'm now good until 2012! Now go get wet! Signature"When you do a good deed, get a receipt in case heaven is like the IRS." |
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