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Scuba Tanks Explosions

Thread Status: Hello , There was no answer in this thread for more than 60 days.
It can take a long time to get an up-to-date response or contact with relevant users.


Mr. Long Post
Apr 22, 2002

This is not new news.
I been reading a lot about these Big-Bangs. Even overall percentage is low, I mean total manufactured cylinders against actual accidents/explosions ( like 12 or so documented....not documented ones ????? ).

Some info to help : You may go to Luxfer to see more or use ur search engine and look for SLC 6351

1. What is sustained-load cracking?
· SLC is a metallurgical phenomenon that occasionally develops in cylinders made of 6351 aluminum alloy, as well as in other types of pressure vessels and structural components under stress for sustained periods of time.
· SLC has occurred in cylinders manufactured by various companies, including Luxfer.
· Cylinders that have been mechanically damaged, over-filled or abused are more susceptible to SLC.
· SLC is not a manufacturing defect; it is a phenomenon inherent in the metal itself.

2. How quickly do the cracks grow?
· Very slowly, as extensive research by Luxfer and outside laboratories has shown.
· No scientific evidence supports rumors and claims of "fast crack growth."
· Cracks typically take six or more years to grow large enough to cause a cylinder leak.
· Because SLC growth is so slow, properly trained inspectors have adequate opportunity to detect cracks during the normal requalification process.

3. How many aluminum cylinders have exhibited SLC?
· Out of a total U.S. population of 1,073,000 Luxfer scuba cylinders made of 6351 alloy, only 1.25% have exhibited SLC.1
· Out of Luxfer's total 6.1-million U.S. population of 6351-alloy cylinders, the SLC rate is slightly less than 0.37%.

10. How can I tell if my Luxfer cylinder is made from 6351 alloy?
· The easiest way is to check the original hydrostatic test date stamped on the cylinder crown.
· Luxfer manufactured 6351-alloy cylinders during the following periods:
· United States: 1972 through mid-1988
· England: 1958 through 1995
· Australia: 1975 through 1990
· After these dates, Luxfer began making cylinders from a proprietary 6061 alloy, which is not susceptible to SLC.

Because of this case I surf a lot these past few days and found out other interesting and important info.

My main concern is that how do you divers in USA and Europe view this problem, I am sure there are bounds to be accidents not reported because many divings takes place in rather remote locations world wide and since the danger will scare divers away too, I suppose dive industry people do not like the whole thing to go out of control.

Anyway any container containing such high pressure is lethal no doubt about it and the world is not perfect, so accidents do happpen .....even the great engineered space shuttle once blew apart. Honestly many more people are killed by drowning or bee stung worldwide than scuba tanks explosions. However, I want opinions from you guys because this is how I think :

01. Scuba realy get moving HOT around the 80's, meaning many almost 20 years old tanks are around. We know that anything older than 12 years old is of 6351 alloy which is SLC inherent.

02. Why the hell are we risking our life ( hhhmmmm, I have a good life ...wha ha ha ) to save some US$200 at the most for a say 80CF tank when we spend hundreds and even thousands on dive trips ? Clubbing cost not yet included !!

03. Is it fair to expect something to last forever, hell no way, I think. Imagine if we assume 12 years serice life for a US$200 tank, 12 years is a lot longer than most modern marriage couple can stick together....wha ha ha ha. So we are looking at US$18.00 a year in deappreciation and so on. Tank maintenance doesn't change new or old, in fact older cost more to maintain ...... (unlike a wive.. J/K ).

I am thinking to ban, within my group of divers and within the maximum reach of my influence towards my old buddies at the dive shops and bla bla bla, tanks older than say.....12 years...even for new 6061 alloy. I mean hydrotesting is good requirement but at 5 years span in between....damn too long if the tanks are getting older. Some country require 3 years in between. Anyway, I am thinking that the 6351 alloy took that many years to be discovered that it has the SLC flaw. This doesn't guarantee that new 6061 will not have some sort of weakness because the majority of oldest 6061 tanks are only 12 years old today. We need time to determine what will be the long term effect/reliability, again nothing can last forever. So who wants to be blown in to pieces first by a 6061 alloy and be a case study....any volunteers ???

Input please people.

Thank U. Arigato. Gracias.

:D :D
Best way to avoid that is to use steel cylinders.

Currently I've been looking at some stuff on more advanced diving, and it seems alu cylinders are only really used over here for stage/deco cylinders, just so that they don't have an effect on bouyancy. Personally I'd never use alu cylinders for my main cylinders, I just feel better with steel.

And your right, there are very few cases of cylinders exploding, any defects likely to lead to an explosion should be found when the cylinder goes for a test.

When you work at a technical dive shop and are certified to inspect pressure vessels (tanks), you'll quickly see what horror stories get dropped off for fills and inspections. We will not fill any 6351 alloy tanks - period. I am amazed that people will purchase used 6351 tanks on e-Bay (yes, they have) and then get upset when we won't fill or service them. The degree of ignorance out there is simply staggering when you consider this equipment is for life support. The issue for us is not how many have structurally exploded and failed (one is too many); rather the evidence is absolutely there regarding the metallurgical deficiency of 6351 aluminum and their propensity for sustained load cracking. As far as we're concerned, they're ticking bombs and don't want to be around when they fail.

Training is the answer for this problem/issue. We posted a large notice next to our cascade for everyone to see. Some excellent information can be found on the Professional Scuba Inspector website - information from the expert on cylinder inspection.

Learn as much as you can about this and don't ever hesitate to (politely and tactfully) correct anyone that displays ingorance about it. If you're going to get into technical diving - steel is the way to go.

Happy Diving :)
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