REAL facts about 6351 cylinders

[Leadking]

For years I have been trying to educate Scubaboard members about cylinder safety and dispel rumors and myths about cylinders. I just "went off" on a poster about 6351 safety and decided a new thread with facts was needed and here they are;

From DOT report; "Measurement of the largest crack at the neck (Figure 17) results in a sub-critical crack extent or “length” of at least 51.7 mm. Using a mean propagation rate of 0.61 x 10-3 mm/hr [10], the time to develop the longest observed crack is estimated to be 9.7 years. A similar calculation performed for the other crack length results in an estimate of 8.3 years. These estimates are a significant fraction of the roughly 13 years that the cylinder was in service, following its first hydrostatic test in 1987."

Report available at;[http://www.phmsa.dot.gov/staticfiles/PHMSA/DownloadableFiles/Files/3al3000.pdf
This one was due to extreme overpressurization; http://www.phmsa.dot.gov/staticfiles/PHMSA/DownloadableFiles/Files/3al2015_57003.pdf

How about that? Real facts! No I think, I heard, just real science. If you have "real science" to the otherwise please post.

p.s. over 7 million 6351 SCUBA cylinders were made.

 

[Bob DBF]

Unfortunatly the links give me 404 errors.

I was sad when one by one the fill stations refused to fill my old AL 6351 tanks. They did pass hydro and vis every time. Since I used them for just shy of 30 years, and have several other tanks, I was not as PO'ed as a number of other folks I know.

It's a bad rap the tanks have taken but I've done my share of shoveling s**t against the tide.



Bob
-----------------------------
I may be old, but I’m not dead yet.

 

[Leadking]

Unfortunatly the links give me 404 errors.

I was sad when one by one the fill stations refused to fill my old AL 6351 tanks. They did pass hydro and vis every time. Since I used them for just shy of 30 years, and have several other tanks, I was not as PO'ed as a number of other folks I know.


It's a bad rap the tanks have taken but I've done my share of shoveling s**t against the tide.



Bob
-----------------------------
I may be old, but I’m not dead yet.

Bob, the links are fixed.

 

[scubafanatic]

 

[Kern]

South West Rocks Dive Center Dive Master looses hand in Scuba Tank Explosion

Man loses leg after gas blast - Local News - News - General - Macleay Argus

This tank was privately owned.
This tank had a current hydro, viz., & eddy current test. These are done annually in Oz.
This tank was made from 6351 alloy.
This tank wasn't overfilled.
The people at SWR will never fill another 6351.
I won't be anywhere near a 6351 tank while it's being filled.
It's a bit like "winning" the lottery; the probabilities are next to nil, but it happens.
Murray is an amazing chap, he was joking about the incident & the outcome just a few weeks ago. I didn't know whether to laugh or cry.

 

[DA Aquamaster]

Small correction...there were over 22 million 6351-T6 alloy tanks made - about 7 million of them were scuba or SCBA tanks.

Kern... if you look at the picture in the article you posted, you will note it is a badly rusted steel tank and the pattern of the failure suggests line corrosion. It also is not a scuba tank - it is a larger steel tank most likely used in the shop's air bank or cascade system.

Obviously, given the interior rust, it was not properly inspected and equally obviously, 6351-T6 alloy had nothing to do with this failure - unless by some sort of strange bastardization of physics, 6351-T6 alloy tanks are causing sympathetic detonations of nearby rusty steel cascade system tanks.

You've just taken internet ignornance and the total misrepresentation of facts to a whole new level. My hat's off to you for a (hatchet) job well done. You should consider a career in liberal journalism.

The fact is that there have in fact been zero catastrophic failures of 6351-T6 scuba tanks due to sustained load cracks since the implementation of eddy current/visual plus inspections over 11 years ago. That is zero - as in "0", "Zilch", "Zip", Nada" - since prior to the year 2000.

 

[Leadking]

South West Rocks Dive Center Dive Master looses hand in Scuba Tank Explosion

Man loses leg after gas blast - Local News - News - General - Macleay Argus

This tank was privately owned.
This tank had a current hydro, viz., & eddy current test. These are done annually in Oz.
This tank was made from 6351 alloy.
This tank wasn't overfilled.
The people at SWR will never fill another 6351.
I won't be anywhere near a 6351 tank while it's being filled.
It's a bit like "winning" the lottery; the probabilities are next to nil, but it happens.
Murray is an amazing chap, he was joking about the incident & the outcome just a few weeks ago. I didn't know whether to laugh or cry.

No doubt a tragic accident. I am sure the regulatory authorities did a thorough investigation. What was the determining cause?

 

[Kern]

As I was stupid enough to put up a link without vetting it properly, I won't take the personal attack personally. Unfortunately, they've just used a stock photo of an exploded tank, instead of the tank involved in the incident.

Below are safety alerts put out by NSW, & Queensland workcover. They both show the 6351 cylinder that exploded. The Qld one, offers this synopsis;

"Initial investigations by Workcover NSW have indicated that the cylinder was being filled correctly and that the cylinder had had visual, hydrostatic and appropriate non-destructive (eddy current) testing. The cylinder was manufactured in 1983/84."

http://www.workcover.nsw.gov.au/for...luminum_scuba_cylinders_safety_alert_2217.pdf

http://www.deir.qld.gov.au/workplace/publications/alerts/alloy_cylinders/index.htm

I haven't been able to track down a copy of the NSW workcover report on the net. If I can, I'll give them a ring tomorrow & see if it's available.

 

[Culcuhain]

that pic of the alum tank in Kern's post look like it blew out from the bottom and not at the neck.... just saying....

 

[Leadking]

As I was stupid enough to put up a link without vetting it properly, I won't take the personal attack personally. Unfortunately, they've just used a stock photo of an exploded tank, instead of the tank involved in the incident.

Below are safety alerts put out by NSW, & Queensland workcover. They both show the 6351 cylinder that exploded. The Qld one, offers this synopsis;

"Initial investigations by Workcover NSW have indicated that the cylinder was being filled correctly and that the cylinder had had visual, hydrostatic and appropriate non-destructive (eddy current) testing. The cylinder was manufactured in 1983/84."

http://www.workcover.nsw.gov.au/for...luminum_scuba_cylinders_safety_alert_2217.pdf

Safety alert - Safe filling of portable aluminium alloy cylinders - Workplace Health and Safety Queensland

I haven't been able to track down a copy of the NSW workcover report on the net. If I can, I'll give them a ring tomorrow & see if it's available.

Kern,

I am not attacking you, I'm trying to have real facts as to the cause of 6351 failures. From all the reports of catastrophic failures of 6351 cylinders I have access to, it shows that PROPER inspections have not been done. If you have access to scientific examinations that indicate otherwise, I welcome them.