How to identify a Luxfer 6351 tank?

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If 50% of the returned cylinders weren't cracked, then wouldn't that mean that 50% were? Pretty significant failure rate in my book.
It's one way to look at the stats. To me, having read repeatedly that the real problem posed by the cylinders is directly due to poor inspection practices, the fact that some "supposed professionals" get it wrong 50% of the time shows where the spotlight ought to be focussed. Better training, not culling perfectly servicable cylinders.

Why would PSI press so hard to keep these cylinders in operation after they have clearly been identified by DOT, Luxfer, and the SCUBA Industry as being a safety risk?

Both the regulatory agency (DOT) and the manufacturer have indicated that the cylinders do not pose a risk if properly inspected (other than the risk assumed by all compressed gas cylinders). PSI's entire position of authority in the industry is based on its impartiality. They make their money whether they say the cylinders pose a risk or not, so what do they stand to gain by fudging the facts (besides a loss of their credability)?

As to why the retail SCUBA industry says they are a risk... I can't say for certain but the fact that they are the ones selling you the new cylinders doesn't evade my notice. Some retailers say they make no money selling tanks but then I have also heard that they make no money doing fills, teaching courses, servicing regs and so on. Am I saying they are definately motivated by profit (no) but if you are in the business of investigating DOT's PSI's and Luxfers motives then you should give equal billing to the shops.

To be perfectly clear; I think every individual has the right to choose to use a 6351 tank or not. As a small business owner myself I also (begrudgingly) believe that every shop has the right to set its own policy in regards to filling 6351 tanks. What I do not believe is that some people should be able to claim a superior position in the discussion based on "professional status" when the position they espouse is directly opposed to the training and certification they represent and they fail repeatedly to base their opinions on fact.
 
Man I can't believe this thread is still going - again.

For all the "numerical facts" being winged around there still seems to be a fundemental misunderstanding about how humans judge risk. Its not strictly by probability. Things like voluntary vs. involuntary, ease of mitigation, magnitude of consequences, benefits of the risky thing or behavior etc. all play a role.

It is a perfectly acceptable conclusion to say that 6351 cylinders are "too risky" to fill. And its also perfectly acceptable for other people to call them "safe". Try not to make the other side "wrong", their values are different than yours so its best to just accept that.

Tossing out more "facts" in an effort to sway someone who has based their conclusions on a completely different frame of reference is disrespectful of their non-probabilistic values.
 


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Tossing out more "facts" in an effort to sway someone who has based their conclusions on a completely different frame of reference is disrespectful of their non-probabilistic values.

Excellent point.
 
I just weld big globs of metal around the neck when my tanks get old and rock on. Amazing what arc welder and some JB weld can do. Just send your tank to me allong with $100 and I will fix ya right up and put an end to all this ( as you will find when you get your first fill ) !!!!
 
Man I can't believe this thread is still going - again.

Tossing out more "facts" in an effort to sway someone who has based their conclusions on a completely different frame of reference is disrespectful of their non-probabilistic values.

I am more than willing to accept that others base their opinions on differing valid criteria and I don't think I will change certain peoples minds on the issue but I also think some people may read threads like this and be confused by what is fact and what is non fact.

I don't think I'm being "disrespectful" for maintaining a position based on fact and by referencing it but I will admit to getting a little hot when I am challenged by someone claiming superior professional knowledge whose position is diametrically opposed to the relevant training, certifying and regulatory agencies involved. So far, because I choose to rely on the best information available and dive perfectly servicable cylinders I've been called cheap, uneducated and unsympathetic to the safety of others. So sue me if I sound a little strident... I'm having a Hans Blix moment.


I just weld big globs of metal around the neck when my tanks get old and rock on. Amazing what arc welder and some JB weld can do. Just send your tank to me allong with $100 and I will fix ya right up and put an end to all this ( as you will find when you get your first fill ) !!!!


That's weird? I just take my tanks in for a vis with V+ and get a report like this:
Picture124.jpg


The pertinent info being: US Divers 6351 alloy tank Manufactured Nov 1976. The trace lines record the inspection of the threaded neck region of your cylinder by Visual Plus and indicates that it is in good condition. Found 0 cracks in recorded data that are longer than 1 thread.
 
HI gang. I have been reading and this has been the most productive forum so far that I can find on the issue and in search of some answers. I hope you don't mind me coming into your world to ask these questions.

My dept had sent in 8 bottles to be checked and all 8 come back condemned for sustained-load cracking ( SLC ).This bottles are made of 6351 alloy and have has been known to develop cracking in the threads.After the bottles were returned I sent in 4 of my newer bottles and they also come back condemned for SLC failures. Now these bottles are made of 6061 alloy and have no known problems for SLC.
As most fire departments would of done I moved on and notified my city council due to this problem and what this cost this would do to my very small budget. I could not accept that 10 bottles from our dept were bad. So begin asking local departments and 2 of our mutual aid departments has had same problem this year for same reasons.I then went to a popular fire forum and again another dept from Western Iowa had posted same issue with SLC as had a few other states as well. I contacted this Chief and found out that they had used same vendor and had claimed same reason for failure.
My next step was to talk to Luxfer and in detail he reassured me that 6061 alloy bottles should not have been condemned and that it was highly unlikely that ours and the other Dept's bottles would have had condemned bottles as the have done many test on 6351 bottles. Luxfer is stating 3 things
1) person doing test does not know what he is doing 2) That they were using outdated software to perform test or 3) just trying to sell new bottles.
Luxfer did say that they discovered a flaw in old version of software that was giving false positives and for the tech this would be one reason for condemning bottles per DOT,but that tech has other ways to double check for this before placing out of service. Luxfer also noted that they have never seen a bottle with 12 cracks as one of our is to have and along with 4 with 5 cracks and several with just 2 cracks. They said out of 1000 bottles tested the might find 1 with just one crack in threads.

Luxfer recommended taking bad bottles in for a 3rd party test.Which is were they are now at a scuba shop in des moines.When I dropped them off this tech stated that there is no way other vendor could of have done test as dirty as the threads were and spent 5 minutes cleaning one bottle that had 12 cracks in the threads as reported from other vendor.When he was done his white rag looked like he had just changed his motor oil. He could not perform test as his probe had been broken and he awaits new probe.

So while waiting for results it was eating at me that possibly it was the software so I called Visual Plus and again they also stated that there is no way 10 out of 12 bottles could have SLC failure and again said what Luxfer had told me about use of outdated software and that a updated version had been released, and that no way 6061 bottles would have SLC failures let along this many Dept's in Iowa . Visual Plus said they would like to see my SCBA bottle files from the vendor as I have no why of knowing what version they were using.

So I call vendor and ask directly for the tech.Tech claims they changed testing due to a new DOT requirement using visual eddy current.
Tech also claims they update software in January and July and my tests were done in May.The other known Dept's also had testing done earlier this year.
I asked for my SCBA bottles files and yet have received them.

Now we have two issue's here 6351 bottles and 6061 alloy bottles.
Luxfer states in the FAQ section of the website that 6061 should not be failing for SLC and this is what vendor is claiming this is what is wrong with bottles.So why is vendor failing bottles when manufacturer said they should not be ? I also need to point out that our 6061 bottles were still under warranty but had to wait 2 months for replacement bottles then charged a $15.00 shipping charge.

Luxfer also states in FAQ page "On Luxfer 6061-alloy cylinders, eddy-current devices sometimes show harmless "indications" that lead to "false-positive" readings for SLC. Well it's may not be harmless to them but our Dept and comsumers need not have to pay for devices mistakes by buying repalcement bottles.

6351 bottles have a low failure rate per Luxfer but has no warranty as Luxfer discontinued use of 6351 alloy in June 1988.
If these 6351 were actually good they are not now due to dot #'s being stamped out and can never be refilled giving us no choice but to buy replacement bottles.

I think that the problem is in the software and that vendor had not kept up with updates thus creating 100's of bottles being placed out of service for SLC within our state with no reimbursement or credit.
If this is the case we would have many departments with no bottles or funds to purchase new bottles ($450.00) each thus creating a safety issue.

So who is right on this issue ?
Is vendor just trying to sell bottles ?
Luxfer covering their butt ?
Software company having a known flawed product.
All the above ?
If this is happening here what is happening across America at fire departments and scuba divers expense.

Can anyone advice when the Current Software Version: 3.7.3.1 for visual plus 3 went into affect ?

Please Advice :confused:
 
Thanks for the post mtndew.
It's unfortunate that this has occured for your department. Please post the results of your review testing so we can better understand what happened in your case.

So who is right on this issue ?
An independant test will go a long way to answering this question but a couple of things you've reported make me wonder.
1. The threads were so dirty the tests couldn't be done. If that's the case it speaks to who/what was at fault.
2. You are having trouble getting the printouts from the original tester. If they stand by their results they should not have a problem verifying them. Mine were taped right on my bottles.

Is vendor just trying to sell bottles ?
Perhaps it is that simple or perhaps it has more to do with a climate of thought that says all older tanks should be culled. When enough people begin agreeing with it, cullings like yours becomes "acceptable" whether it is accurate or not. If the vendor is a fault that is.

Luxfer covering their butt ?
About what. The tanks or the testing equipment.

Software company having a known flawed product ?
Perhaps, it's possible but then again... what about those dirty threads. If the tank isn't even in testable condition how can one get to the flawed software.

All the above ?
Probably not but your second test results will tell.

If this is happening here what is happening across America at fire departments and scuba divers expense ?
I don't know but to some the expense shouldn't matter. Stories like yours need to be followed through to the end so we can see what is going on.
 
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mtndew,
Even with outdated software, it boggles the mind that your fail rate would be so high. That should have been a red flag even to the tester to look for another answer.
Did the vendor have authorization to stamp out the DOT numbers? What does your contract with him say?
 
I was recently given two pair of USD Luxfer Twin 50's and an Alum 80 also
Luxfer USD all pre 1988. I kept the two best 50's and had them hydro tested,
and eddy current checked, the rest I scrapped out, mostly due to the fact I
already have five newer tanks. I now have a set of twins for just the cost of
having them tested. One local dive shop will not fill them, and I respect that,
the shop that tested them will fill them. I've done a lot of research on the 6351
subject, and respect everyone's opinion, if properly tested, by a competent
test facility, I have no problem with them. Most of the failures happened during
hydro, and that's a good thing. The tanks that did fail were for the most part
abused, overfilled.
 

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