Old steels denied fills due to store "policy"

[rhwestfall]

This thread has almost (and I repeat - ALMOST) had me dig out the two USD "Z bottles" buried in the crawl space (and I believe they are full)....

I have been pondering the scrap value or possibly a grill...

 

[markmud]

You made my point. The wing catastrophically failed at 154% of design load. Steel scuba cylinders are routinely tested to 166% of design load and the failure rate is infinitesimal. 3AL cylinders tested to failure typically let go at 250% of design pressure. I have no idea what percent of design pressure 3AA cylinders fail at, but it isn't 154%.

Edit. FOund some testing data. 3AA cylinders tested to failure at 17,000 PSI for a 2250 cylinder. 750% of design.

Thanks Wookie,

I know you weren't supporting my argument per se, but you did anyhow.


markm

 

[Diving Dubai]

They are mostly made of steel!

Not true

They used to be predominately Mag alloy, the trouble is when you scale up to larder jets, the weight (and size) of an alloy U/C for the required strength is greater than that of a steel U/C for the same loads

There is always a trade off - weight, size, cost , strength there is no one universal solution One generally picks the solution that offers the least compromises

 

[Diving Dubai]

Thanks @JohnnyC for posting those videos. Brings back memories

I was in the invited crowd for the 777 wing test. On the A380 UC We had 5 complete design failures before we got to the successful design. Saying "I told you so@ to the design team - even in jest wasn't the best way to make friends

 

[markmud]

According to the PSi document cited above, they have knowledge of 24 steel tanks in 2011

What isn't clear is how why and when etc

Hi DD,

I have searched for the PSI document cited above. Can you direct me towards it?

I understand that a number of steel tanks have ruptured while undergoing hydro testing.

Here is my gut feeling, or big picture vision, on this issue.

I "feel" that there are several people on this thread who don't think that most of us can make a judgement call regarding a piece of equipment and its ability to perform according to its warrant of merchantability. This issue has arisen on other threads regarding other issues.

We have people on this thread who are or have engineering backgrounds, who worked in nuclear propulsion, who worked as marine surveyors under the tutelage of a retired aircraft accident investigator. One of us managed a materials testing lab at an academic institution. Many of us have hired consultants, including metallurgists and engineers, who provided expert advise.

It is my contention, that several people on this thread don't trust me, and many others, to learn about a certain product or procedure by studying the manufacturing, regulatory, and usage history of said product, and to then make an informed decision as to whether, in this case, a steel tank is serviceable or not.

As The Chairman stated in one of his posts, he discovered an issue with a piece of equipment, he serviced it, and then had it tested following industry and DOT standards. He diagnosed a problem, he created a mitigation plan to resolve the issue, and then followed through with a serious test. His tank is still in service.

I believe, and correct me if I am wrong, you don't think The Chairman, or Wookie, or me, should make those decisions. Instead, an arbitrary retirement age should be placed on steel cylinders so "we" don't hurt ourselves or someone else.

Just my feeling on this! I have received this message from other people on Scubaboard regarding different issues--almost all of them are instructors!

If you respond, please provide citations that prove your point that 30 year old steel tanks, that have been tested by competently trained people who are performing their jobs in a workman like manner, are dangerous.

Respectfully and cheerfully,
markm

 

[markmud]

Not true

They used to be predominately Mag alloy, the trouble is when you scale up to larder jets, the weight (and size) of an alloy U/C for the required strength is greater than that of a steel U/C for the same loads

There is always a trade off - weight, size, cost , strength there is no one universal solution One generally picks the solution that offers the least compromises

Yeah,

I think you just proved my point. I may not have stated my point well, but...

markm.

 

[tursiops]

Just to correct a few things, for the record, before this thread gets closed down....

I agree . The trouble is the sdi website dosnt have an means for independent instructors to be found. If you are not willing to pay for the facility to be on the site then your instructors are not searchable.

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

VIP is not an SDI course, it's TDI.

It is indeed an SDI course, not TDI.

You can't shearch independent sdi instructors with that tool.

See above. SDI instructors cannot be independent.

While Hydro inspectors have to re-cert every 3 years vis inspectors do not.

While Hydro testers have to re-cert Vis inspectors do not

PSI tank inspectors must recertify every three years.

 

[Jiminy]

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

 

[Jiminy]

Does anyone use these safety boxes in the US?

 

[Basking Ridge Diver]

Does anyone use these safety boxes in the US?

Any self respecting fire company uses the enclosure. I fill my tanks with my fire company and it is required. Hence I dive independent doubles because you can not fill doubles in the enclosure.