How to identify a Luxfer 6351 tank?

Please register or login

Welcome to ScubaBoard, the world's largest scuba diving community. Registration is not required to read the forums, but we encourage you to join. Joining has its benefits and enables you to participate in the discussions.

Benefits of registering include

  • Ability to post and comment on topics and discussions.
  • A Free photo gallery to share your dive photos with the world.
  • You can make this box go away

Joining is quick and easy. Log in or Register now!

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.

It is possible although highly unlikely all of these really failed. I have heard on numerous occasions at local dive shops "All of XYZ" tanks will be condemned. While I stand on the side of getting unsafe cylinders off the street, particularly for what we would all consider severe duty/environment and to protect the safety of paid and volunteer firefighters. If you look at it from a negligence lawsuit perspective, it will be cheaper to replace them anyway than take a risk of a death or injury lawsuit.

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.

Why would departments not plan replacement of certain equipment anyway. If you have ten tanks, and want to keep them a maximum of ten years, replace 1 a year, then you will never have a tank older than ten years. The department can then sell them as used on the open market, or dispose of them. The difference is running the risk of having to replace 100% of the item in question at once, or a small budgeted amount annually.

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.

On point 3, does the hydro facility also sell bottles? If so do they have an agreement with Luxfer or someone else. Why would you throw away 10 Luxfers, and by 10 more Luxfers?

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.

As I suspected, automatic condemnation. However, I still personally feel these should not be used in your environment, let alone scuba... your safety is not worth saving a few bucks.

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,

Remember when they told us computers would make our life easier, our work weeks shorter, utopia..
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.

Stranger things have happened...

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 they have to figure out how to forge 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.

Let's hope their houses do not catch on fire in the mean time, tell them to pull their head out of their axx. As to speak with the regional rep, or the company rep.
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.

shipping, well, nobody eats shipping problems, no matter who's problem it is for the most part.
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.

Nobody is perfect, everyone makes mistakes, it is the response to the mistake that makes the difference.
So who is right on this issue ? You are
Is vendor just trying to sell bottles ? Maybe, doubt it, change brands.
Luxfer covering their butt ? Always
Software company having a known flawed product. What else is new, bet it runs on a windows computer.
All the above ? YES
If this is happening here what is happening across America at fire departments and scuba divers expense. It certainly could be a racket to target vulnerable Fire Departments and increase the bottom line in a tough economy.
 
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.

You missed the part about SLC being acceptable at all, at even 1:1,000,000 or less rate. To some people the V+ testing is too "black box", relying on their competitor's shop down the street to VIP tanks properly too nerve-wracking and most critically, the consequences to their kids and families just too high.

Sure they are more likely to be killed in the car on the way to the shop. Just because they accept that risk does not mean they are obligated to accept the additional risk of SLC vulnerable tanks once they arrive.

Whoever runs the fill station can make up whatever rules they wish on top of DOT, PSI, CGA, whatever guidelines. If you dont like their additional requirements, find another compressor or buy your own.
 
You missed the part about SLC being acceptable at all, at even 1:1,000,000 or less rate. To some people the V+ testing is too "black box", relying on their competitor's shop down the street to VIP tanks properly too nerve-wracking and most critically, the consequences to their kids and families just too high.

Sure they are more likely to be killed in the car on the way to the shop. Just because they accept that risk does not mean they are obligated to accept the additional risk of SLC vulnerable tanks once they arrive.

Whoever runs the fill station can make up whatever rules they wish on top of DOT, PSI, CGA, whatever guidelines. If you dont like their additional requirements, find another compressor or buy your own.

I don't disagree with anything you've said and have even stated several times that individuals have the right to choose to use or fill any type of cylinder they want. That is a personal choice. I have also stated that it is reasonable for a shop to want to do a vis on the tanks they fill.

The question with this issue for the undecided is what criterion will they use to make such a decision (or whether they want the choice to make a decision taken out of their hands by others who may not use the same criteria as them):

Personal ancedotes,
a graphic image,
guilt tactics,
belittling opposing viewpoints,
claiming professional expertise,
fact.

I choose to use and present facts. I believe the information from DOT and PSI/PCI and act accordingly. That is my viewpoint. This is a discussion forum so I expect and welcome others to challenge my viewpoint (in a constructive manner). It would be helpful if some others would clarify what motivates their position and stand open to the same examination; especially when their viewpoint is that someone else should scrap their tanks because of it.

Why aren't you questioning other claims in the same way you want to challenge me? Do you believe 80-90% of 6351 tanks legitamitely fail vis? Do you believe it is valid to require a vis and hydro on 6351 tanks? Do you believe older 6061 tanks should also be culled from service? All those opinions would slip by and may pass for fact if someone didn't challenge them.
 
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?


Well never had a contract per say as this is the distributor of the cylinder not the manufacturer.As a D.O.T.testing shop I was told that they must XXXX out number's by law.
 
.....As a D.O.T.testing shop I was told that they must XXXX out number's by law.

Do they do Hydros or just Visual inspections? An actual DOT certified testing facility would/should have known better. Never seen a VIP tester X out a tank, not even a bad one.
 
Why would departments not plan replacement of certain equipment anyway. If you have ten tanks, and want to keep them a maximum of ten years, replace 1 a year, then you will never have a tank older than ten years. The department can then sell them as used on the open market, or dispose of them. The difference is running the risk of having to replace 100% of the item in question at once, or a small budgeted amount annually.

We do and did with our newer 6061 bottles and now they are claiming they are failing for SLC as well.


On point 3, does the hydro facility also sell bottles? If so do they have an agreement with Luxfer or someone else. Why would you throw away 10 Luxfers, and by 10 more Luxfers?
Yes they do test and sell bottles.1000's a year. They are the only distributor in the state for Scott.We decided on these bottles due the longer in service life compared to a wrapped cylinder.

As I suspected, automatic condemnation. However, I still personally feel these should not be used in your environment, let alone scuba... your safety is not worth saving a few bucks.
Automatic condemnation for sole purpose of selling bottles.
I also would like to state this bottles were sent in for 5 yr hydro/eddy testing only.We have our own enclosed fill station-cassade system and compressor which we also bought thru this vendor.So yes safety is are # 1 priorty



Nobody is perfect, everyone makes mistakes, it is the response to the mistake that makes the difference.
How true and this is all that I'm after.If this was just a mistake great fess up and fix the issue.

Do dive shops not use a enclosed fill station to fill bottles ? I get the impression from most posts that they do not. If not then why?
 
ok, here are some facts.

Steel has an endurance limit and aluminum does not, and the endurance limit of a material is the maximum stress at which it will never exhibit fatigue. This means that you can make a steel tank that will never "wear out" but that is not true for aluminum. (I am not saying that the working pressure on current steel scuba cylinders is within the materials endurance limit)

The fatigue life of aluminum alloys is governed primarily by crack initiation, which is accelerated by the presence of microporosity in the alloy structure. 6061 alloy aluminum WILL eventually crack due to fatigue. (here is an opinion; 6061 alloy aluminum tanks should fail hydro before they crack significantly)

material fatigue occurs exponentially.

Aluminum tanks have a finite lifespan.

It is possible for a tank to pass inspections and then fail catastrophically before the next inspection.
 
They do both test. Excuse me for not knowing your term VIP.
It might have to do with National Fire Protection Association standards(NFPA) but I have yet to find it. All they claim is was new testing rule or whatever that is calling these tanks condemned.
The only thing that has changed is to retest 6351 bottles per Luxfer every 2.5 years instead of 5 years.
The shop tech said that he updates software in Jan and July each year and mine where tested in May. Big time span still for as many bottles they inspect.If the problem was in the software then that is inexcusable as you stated.

Now my next problem is the Dive shop I've taken my tanks too.If by chance he does found any issues he has no way of doing anything with them under warranty nor does his supplier since vendor I'm having issues with is the only distributer in the state.
That and it took 2 months to get my 6061 bottles replaced under warranty from said vendor.
 
ok, here are some facts.

It is possible for a tank to pass inspections and then fail catastrophically before the next inspection.

Are you refering to 6351 tanks and failure due to SLC? And, are you claiming this is fact (or personal opinion)?

If fact, please refer to a specific case in point, as everything I've read on the subject states otherwise.
 
I was referring to any tank that has a working pressure that is above its endurance limit, and I never said that it has happened... yet. All that is necessary is a tank that is close to the end of its life to pass inspection by a small margin and get enough cycles before the next inspection.
 
https://www.shearwater.com/products/perdix-ai/

Back
Top Bottom