Old steels denied fills due to store "policy"

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For anyone who wants the data.

https://www.luxfercylinders.com/support/faq-slc-how-many

  • Out of a total population of approximately 1,073,000 Luxfer scuba cylinders made of 6351 alloy, only 1.25% have exhibited SLC.
  • Out of Luxfer's total 6.1-million population of 6351-alloy cylinders, the SLC rate is slightly less than 0.37%.
  • While we do not have complete statistics on cylinders manufactured by other companies, industry experts estimate that out of a worldwide population of more than 30 million 6351-alloy cylinders, far less than 1% have exhibited SLC.
To reiterate the point, bullet point number one is scuba specific, and is a subset of each of the other two points. There is a tendency for people to read that second point’s lower rate for ALL Luxfer 6351 cylinders, and want to apply it directly back to scuba.
Interesting that in the context of these three statements, it appears that non-scuba, non-Luxfer cylinders have a much higher rate of SLC than Luxfer non-scuba. (I am assuming all manufacturers produced scuba in similar proportion to total cylinder output.)

Also note that Luxfer cites an industry expert total population of 30M cylinders, and industry expert PSI cites 50M. Perhaps Luxfer excluded some population of “out of service” at the time, such as Norris and Kaiser, but I would not assume that.

Bottom line, is that it is usually not difficult to find and/or spin authoritative numbers to argue a different viewpoint than someone else’s numbers.

Another few words on what I will agree is an extremely low incidence of catastrophic failure of 6351.
First, that low rate is poor solace for the fill station operator that experiences it first hand.
Second, that failure rate is highly skewed - it does not exist in a vacuum where there were zero proactive measures to remove a cylinder prior to failure. They occur in spite of those measures. Even if they can be traced back to a missed opportunity due to substandard testing, that testing is part of the world in which we live, and must remain included in any risk assessment.
I will still fill a 6351 cylinder that has an annual VIP and annual eddy current test, but would not lose much sleep over it if tomorrow the DOT banned them outright.

The numbers I would like to see are the quantity of scuba 6351 structural catastrophic failures since the requirement for eddy current testing, and the number of scuba 6061 catastrophic structural failures from each era. And by structural failure, I mean to exclude failures due to abuse. Although now that I think about it, if one alloy is significantly more resistant to abuse than another, that is also relevant as once again it is part of the real world in which we operate.
 
Does anyone use these safety boxes in the US?


In the States, this is called a containment fill station, which I have mentioned a number of times previously in the thread, as have others.
 
I'd like to see a tank explode.
 
In the States, this is called a containment fill station, which I have mentioned a number of times previously in the thread, as have others.
We have two of them at the aquarium in which I volunteer.
 
Just to correct a few things, for the record, before this thread gets closed down....


SDI does not have independent instructors; everybody has to be affiliated with a shop, that is an SDI shop.


It is indeed an SDI course, not TDI.


See above. SDI instructors cannot be independent.




PSI tank inspectors must recertify every three years.


Not true. This policy changed about 2 years ago
 
For anyone who wants the data.

https://www.luxfercylinders.com/support/faq-slc-how-many

  • Out of a total population of approximately 1,073,000 Luxfer scuba cylinders made of 6351 alloy, only 1.25% have exhibited SLC.
  • Out of Luxfer's total 6.1-million population of 6351-alloy cylinders, the SLC rate is slightly less than 0.37%.
  • While we do not have complete statistics on cylinders manufactured by other companies, industry experts estimate that out of a worldwide population of more than 30 million 6351-alloy cylinders, far less than 1% have exhibited SLC.

Also here is a link to a steel cylinder exploding the poor tank monkey gets knocked on his butt

https://www.divinghq.info/single-post/2017/07/22/Scuba-steel-cylinder-blast

Hi Jiminy,

Note that the rusted tank did not shrapnel like a hand grenade. That is a design feature. I would not have filled that tank.

Who didn't train that fill tech?

cheers,
markm
 
I have searched for the PSI document cited above. Can you direct me towards it?
I couldn't find it either. Thanks for asking!
 
In the States, this is called a containment fill station, which I have mentioned a number of times previously in the thread, as have others.
In the States, this is called a containment fill station, which I have mentioned a number of times previously in the thread, as have others.

ah ok I didnt realize they are the same thing
Hi Jiminy,

Note that the rusted tank did not shrapnel like a hand grenade. That is a design feature. I would not have filled that tank.

Who didn't train that fill tech?

cheers,
markm

According to the article it passed hydro but who really knows unless someone can dig up an accident report not sure which agency in Israel would do that. I suppose if they had salt water intrusion in the cylinder some how that would be enough time

This steel cylinder in the video has passed a Hydro test in 2016
 
The diving federation here doesn't publish the accident reports. They claim that the number of divers here is so small that they can't anonymise them. I can believe that.

However, given how people here gossip, even if they were to manage to anonymise the reports it wouldn't matter. The "guilty" parties would out themselves. :shakehead:
 
https://www.shearwater.com/products/swift/

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