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diverdad
09-01-2007, 20:16
well it started about 3 years ago. my bought my ow class and gear i used the lds equipment for certification so i did not pay attention to my new(used tank). well a few weeks ago i planned on doing some local dives so i took my tank in to inspected and have it hydro tested. well the problem started after my first dive and went to refill my tank. they refused to refill it because it was a walter kidde made in 1987. needless to say i was upset because i had just had it tested. i e-mailed my lds and this is what he said(i have removed the names to protect all who are involved)

I am sorry that you were MIS INFORMED!!! XXXX does not know what they are talking about as the DOT Laws state that the Tanks have to now be ECT Tested and Yours was. and then It passed a Hydro as well. Your Tank is in PERFECT Condition and can be filled anywhere in the USA. We no longer go to XXXX as they are IDIOTS.

i would appreciate your replies and your advise( most larry's and his crew's)

Flatliner
09-01-2007, 20:35
This probably won't help, but I have heard that most shops in the Keys at least won't fill tanks that are from that period regardless of test status.

NitroWill
09-01-2007, 20:41
Not just in the Keys, must shops anywhere in Florida wont fill ANY tanks made before the 90s..

CrzyJay456
09-01-2007, 20:45
didn't larry say that he wont fill any aluminum tanks from before 90 or something like that?
some problem with the aluminum??

scubasamurai
09-01-2007, 20:51
i just saw my dive shop won;t fill anything pre 1990 or earlier, bad blood or something sorry dude . maybe post those tanks on ebay with all those chinese made toys

NitroWill
09-01-2007, 20:51
didn't larry say that he wont fill any aluminum tanks from before 90 or something like that?
some problem with the aluminum??

Most shops wont..
Take a look at the Luxfer thread in this forum and itll give a little more insight why

JahJahwarrior
09-01-2007, 21:39
This is a very very very very very very very common topic. If you do a search here, you might find some threads on it. Scubaboard, though, probably has HUNDREDS. Not all are useful, but some of them have VERY thoughtful information, and the RIGHT information, from credible sources. I'd really suggest you go over there and start reading.



The long and short of it is, you are probably SOL with the tank. It will be a hassle for you no matter where you go. "ECT" is eddy current testing. As for "perfect condition," that's not necessarily true. A crappy inspector can very well miss signs of cracks, and these older tanks ARE known to crack. I am not 100% certain, but I believe Walter Kidde no longer makes scuba tanks, and when they did, they used the 6351 alloy, which is the alloy known to have problems with SLC, sustain load cracking. Most shops down in Florida will not fill these, because there have been explosions and deaths, if your tank happened to explode, anyone damaged could sue the shop for gross neglicence. "So Scuba Store, are you telling me that the DOT has reccomended that these tanks be filled only when no one else is in the store (And, the DOT HAS reccomended that only one person bein the vicinity when filling these older tanks, I am 99.9% certain I read that in the DOT document posted on Scubaboard.), and that there have been several explosions and deaths from filling these types of cylinders in your very own state, and you still filled it?????" Therefore, even though the danger is not exceedingly high, most shops are on dangerous ground if they fill it.

To buy a new tankis rather cheap, $150 is the most I'd pay for an AL 80, and I want to say Leisure Pro has them for $115 on sale right now. That's cheaper than a good wetsuit. I wouldn't bother dealing with the tank, but there are some people who use their own fill stations and inspect their own tanks that might be willing to but it. Also, I understand you can take the tank to a scrap shop and get some money for the metal. In my opinion, coming from someone who owned one of these cylinders a year ago, and now has two new al 100's ($125 each, on sale), it's not worth the hassle or potential safety risk.

in_cavediver
09-01-2007, 21:51
What JahJah said is dead on. Ultimately, it doesn't matter whether your specific tank is perfect. The material its made of is flawed, we know it is and most importantly, the risk reward isn't there for a dive operator. Also note that the last meeting of the DOT when they discussed options and added Eddy Current testing, many more draconian options were ruled out simply because of 'self policing' and the 'increased dropout' rate of these tanks.

Look at it this way. Why should I, a fill operator, fill a tank that has a history of failure for an at best break even proposition? Also, we know the risk of failure is remote, but when it occurs, it has devastating effects. Again, why risk it for a break even at best proposition?

It starts making more sense when you look at from the other guys perspective.

ScaredSilly
09-04-2007, 15:12
Ad nauseum

Read this:
http://hazmat.dot.gov/pubs/reports/cylinder/3al_advisory.pdf

If a cylinder falls under the above, then the next hydro ya gotta do this:

http://dmses.dot.gov/docimages/pdf97/411928_web.pdf

Anything else out there is BS.

QED

That said a store can do whatever they damn well please - however it may not please you or them.

ScaredSilly
09-04-2007, 15:22
The material its made of is flawed

A nit-pick here. The material is not flawed. 6351 is still used today, just not for high pressure cylinders. The usage of this material in scuba cylinders was found not to be ideal because of the long terms affects and SLC. You could say the choice of materials was found to be flawed - just like one can say the decision to cut square holes instead of rounded holes in aluminum airplane skins was found to be flawed.

BTW - the new eddy current test is ONLY for SCUBA, SCBA, and O2 cylinders. My older CO2 cylinder is not subject to the eddy current test. However, I had it eddy tested as well.

in_cavediver
09-04-2007, 17:30
The material its made of is flawed

A nit-pick here. The material is not flawed. 6351 is still used today, just not for high pressure cylinders. The usage of this material in scuba cylinders was found not to be ideal because of the long terms affects and SLC. You could say the choice of materials was found to be flawed - just like one can say the decision to cut square holes instead of rounded holes in aluminum airplane skins was found to be flawed.

BTW - the new eddy current test is ONLY for SCUBA, SCBA, and O2 cylinders. My older CO2 cylinder is not subject to the eddy current test. However, I had it eddy tested as well.

Agreed. My choice of words was less than ideal for the nitpicking. Case in point, we agree that for HP use, 6351 is a flawed choice.

DennisW
09-05-2007, 08:42
If your tank passed hydro and an eddy current test, there is nothing wrong with it. Does the shop have to fill it? No. They don't have to do anything. They can also lose business because of it. More and more shops are beginning to refuse to fill any tank made before 1988, even steel tanks. They just want to sell new tanks. I have told several shops that I will never buy anything from them and I will recommend that other divers do not use their shop. Unfortunately in Virginia Beach, the biggest shop that takes out divers, refuses to fill the older Al tanks. I will limit my business with them to the charter boat.

JahJahwarrior
09-05-2007, 10:17
If your tank passed hydro and an eddy current test, there is nothing wrong with it.

Technically, that is somewhat sort of right. SLC slowly leads to cracks forming, over time. A crack might not be noticiable when it passes, but a year later, when your tank has been stored under pressure, it might have progressed much further! I am not certain, but I think it is also possible for some cracks to appear when the tank is put under pressure, but to "close up" when the pressure is removed, making it very hard for an inspector to see them. (I'm not certain on that, if anyone can tell me they've heard that too, or that it's a myth, I'd appreciate it. I think one of the local VIP guys told me that)

Basically, 6351 alloys slowly crack over time under pressure, statistically speaking. I would consider any 6351 tank to be a ticking time bomb, and I would also consider them to be more dangerous than a similar, non-6351 alloy tank. You'll notice the DOT prohibits carrying hazardous materials in them.

So if I had a 6351 tank, I would not store it under pressure, and I would not store it near my living quarters. And I'd make darn sure I got it vipped annually by the best guy around and I'd pay him more to take his time looking for cracks, because at some point they are almost bound to appear. They may or may not cause a deadly explosion when they do, but I want to err on the side of safety, and while I consider the tanks somewhat safe, I do not consider them to be perfectly safe.

awap
09-05-2007, 10:36
I must still be missing something.

First off, shops that refuse to fill tanks that are not 6351 because of their age are just lazy, stupid, and/or trying to force you to buy a new tank. Rejecting all pre-1990 tanks as well as steels and Catalina is simply a scam that we should not tolerate.

Secondly, as I read the links in this thread, I get the impression that the only explosive failures (2 I think) involving 6351 tanks were not related to the SLC problem. Engineering analysis of the SLC problems concludes that the failure will occur as a non-explosive leak as the cracks develop.

So what am I missing?

in_cavediver
09-05-2007, 11:09
I must still be missing something.

First off, shops that refuse to fill tanks that are not 6351 because of their age are just lazy, stupid, and/or trying to force you to buy a new tank. Rejecting all pre-1990 tanks as well as steels and Catalina is simply a scam that we should not tolerate.

Secondly, as I read the links in this thread, I get the impression that the only explosive failures (2 I think) involving 6351 tanks were not related to the SLC problem. Engineering analysis of the SLC problems concludes that the failure will occur as a non-explosive leak as the cracks develop.

So what am I missing?

The one detail not yet mentioned was the real cause for concern with 6351. That was a failure mode that wasn't leak before burst which is required of all HP tanks. SLC wasn't anticipated and didn't show during the initial testing validation so they never saw this failure mode until much later in the tanks service life. That said, the number of documented failures is very low and its hard to draw meaningful data from it. (remember, most tanks were condemned prior to failure).

JahJahwarrior
09-05-2007, 21:38
You are WAY off on your number of tank explosions. I think it's been more like 15. Also remember that alot of the time a life is lost, and every time part of a shop is destroyed. :)

Link to a Walter Kidde tank that exploded, taking half of the filler's hand withit. (http://www.napsd.com/cscuba.htm)

This article says 12 explosions in dive shops, numerous more while hydrotesting (http://www.abc.net.au/farnorth/stories/s1610135.htm)

This undated article also says 12 explosions in US, 17 worldwide, it's at the bottom of the article (http://www.scubadiving.com/gear/tanksnweights/GR_tanks_consumers_guide_to_scuba_tanks)

Also, you are wrong about their explosion. The tanks were supposed to be designed to crack and leak out the air slowly if something happened. SLC prevents that from happening. If you look at the pictures, these tanks actually EXPLODE, as in, pieces go flying! One article shows the tank in multiple, 3 or 4, pieces. Another article shows how half of the upper portion of the tank came off.

The danger from these tanks is real. Tonnes of them fail hydro, by cracking inside of the hydro test station. That's why you don't see so many of them around anymore.

JahJahwarrior
09-05-2007, 23:01
While looking for info on tank stripping, I came across info from Luxfer on SLC and the danger. They say 11 scuba explosions, 6 in US, 5 elsewhere, and 20 ruptures total of various 6351 alloy tanks. But, they also tell you at the bottom of the page that their data is from early 2005. However, I like how they lay out all of the data, so I'm providing a link, because while their numbers might be a little off (more explosions might have happened. I know for a fact that Phil Ellis's shop, Tech Diving Limited, had a 6351 alloy cylinder start leaking, very much like in one of the links I provided above, agressively and they had to act very quickly to shut off the fill station, evacuate the store and drain the tank. Fortunately, the crack there opened slowly and did not rupture violently like some other tanks, but it was enough to make them refuse to fill an 6351 alloy tank.) their data is sound and has very little bias.

Luxfer SLC FAQ (http://www.luxfercylinders.com/support/faq/sustainedloadcracking.shtml)

danielh03
09-06-2007, 00:40
We have a saying were I work. "You own your safety record". With that said, if you feel your tank is safe, and can find a shop willing to fill it, then you two are taking the risk. If you feel your tank is not safe, then dont fill it, scrap it and take what ever profit you get and put it towards a shiny new ST's tank! Just my 2 cents

DennisW
09-07-2007, 08:46
As far as I know, there has never been a tank failure from a tank that has passed both hydro and an Eddy Current test. I could be wrong, but I don't think so.

The reason for the Eddy Current test (or Viz Plus) is to detect the cracks that are very difficult to see. This is an electronic test and only someone trained to used the equipment can use it properly. Most tank monkeys don't know what they are doing. I've seen them try to do an eddy current test on a steel tank.

I will say again, any 6351 tank that passes hydro and the eddy current test is ok and should be filled with no reservation.

ScaredSilly
09-07-2007, 09:51
Phil Ellis over at Dive Sports would disagree with the above. They had one come through where they had done the eddy test and it was leaking but did not blow up.

DennisW
09-07-2007, 12:36
I would suspect the test that was done on that particular tank as being a faulty test. Like I said, only a properly trained technician can perform the test properly. However, all tests are not perfect and neither are all people. So, a tank could fail after passing hydro and a viz plus, but it is highly unlikely. Sounds like this one was very close to a catastrophic failure. Scary.

I have one old Walter Kidde tank that I use mainly to fill my airplane tires. So, unfortunately, it is under pressure most of the time. Each time I get it filled, I have it tested at the shop where I know they are properly trained.

JahJahwarrior
09-07-2007, 14:26
We need to figure out how often the tests are effective. If so many people are doing the eddy test wrong, then many of the tanks out there are dangerous.

in_cavediver
09-07-2007, 17:30
OK, step back a minute and do a simple cost benefit analysis on 6351 tanks from a non-owner perspective

1) Fills are not a money maker or profit center.
2) Tank/material have a known documented history of SLC and catastrophic failure.
3) Failures may be extremely rare but when they occur, they have devastating impacts. (fatalities, maining etc not to mention structual damage and collateral damage to other inventory/equipment)
4) Two other tank material options are prevelant and offer a much better safety record (steel and 6061). These options are also fairly cheap given the amortized cost of a 6351 tank over its lifespan. (less than $10/year for 6351. Same time span, 6061 is about $10/yr and steel is about $20/yr)

Where is the incentive for a buisness to keep using, filling or servicing these tanks?