Tank help

[pumpkin72]

I am looking at buying a tank. I found one with a recent hydro for $100. The numbers on it are.

ctc-dot E6498-3000 3AL Serial # P295487 Date 12-80 Hydro 03 (268) 09



Is this worth buying and is the age of the tank a concern

Thanks in advance BoB

 

[polardiver]

Seems like a reasonable price for a current hydro Al tank if it has a valve like you want. Tanks last many years if they are not abused and maintained.

 

[tfsails]

Lots of shops will not fill a tank marked "E6498" because it's an older alloy. Some hydro facility somewhere probably stamped the "3AL" above the E6498 which was legal at the time. I'd stay away from this tank if I were you.

 

[pumpkin72]

What does the E6498 mean?

 

[DA Aquamaster]

E6498 was the special permit under which Luxfer made some of the original AL 80 tanks using Alcan 6351-T6 alloy.

Eventually the Luxfer and Walter Kidde special permit aluminum 80's were certified under the 3AL standard and were supposed to be stamped "3AL" the next time they came in for hydro testing.

As long as you can get it filled locally, I'd buy it, but probably not for $100.

 

[SDAnderson]

What does the E6498 mean?

The long answer: Metallurgical Evaluation of DOT-E-6498-2216 Cylinder

The short answer: You're going to die. Just kidding. Well, sort of. It's an old alloy that has developed a reputation for failing, sometimes very dramatically.

 

[mike_s]

I am looking at buying a tank. I found one with a recent hydro for $100. The numbers on it are.

ctc-dot E6498-3000 3AL Serial # P295487 Date 12-80 Hydro 03 (268) 09



Is this worth buying and is the age of the tank a concern

Thanks in advance BoB

that 1980 initial hydro reeks of T6351 Alloy which is has an issue with SLC (substained Load Cracking). (as shown in the above pic by ReefRaf.


I would reccomend NOT buying that cylinder. While some folks will argue there is nothing wrong with these cylinders, and I used to argue the same thing, there have also been some cases of these cracking/failing right after they passed a hydro test.

All the shops in my area won't fill those cylinders. most dive shops in Florida won't either.


$100 for a T6351 cylinder is really overpriced also.

no sense paying that much for a cylinder that you can't get filled at many of the dive shops.

your $100 is better spent on a newer aluminum or a steel cylinder.

 

[rstofer]

Brand new Al 80 tanks are about $150. Why mess with this one?

Richard

 

[DA Aquamaster]

It's an old alloy that has developed a reputation for failing, sometimes very dramatically.

Truer words have never been written. 6351-T6 alloy tanks have a REPUTATION for failing dramatically. That has not actually happend due to sustained load cracking of a properly inspected 6351-T6 alloy tank since 2000 when the current eddy current / visual plus inspection protcols were implemented - and there are millions of those tanks in service in SCUBA, SCBA, medical O2 and CO2 service. Since 2000 all of the very few SLC related failures in 6351-T6 tanks have been of the leak before burst variety, not catstrophic failures. That is no surprise as that is how it is supposed to work by design.

Requalification facilities (hydro testers) detect many SLC cracks and pull the tanks from service and other visual plus inspectors in the industry detect more (including some false positives.) The DOT now mandated visal eddy testing with each hydro test as based on field reports and the body of evidence collected since 2000, an inspection every 5 years will catch SLC cracks before they reach the point of catastrophic failure given that SLC cracks propogate slowly.

So in effect, the risks of buying a 6351 T-6 alloy tank are:

1. It may fail a visual inspection due to an SLC at some point, or far more likely

2. you will encounter shops that refuse to fill them due to their reputation and in ignorance of the statistics, and actual safety record of properly inspected 6351 alloy tanks in service.

I have not see a new $150 AL tank in a dive shop in awhile. You can find them on-line for that price, but when you add a VIP and fill, you are again pushing the $180 mark and shipping if it is charged will put you over the $200 mark you see in local dive shops. That said, $100 is still too much for a 6351-T6 alloy tank due to the increased potential that it will have a shorter service life and be harder to get filled.

As an aside, Catalina also made AL 80s prior to May 1988 but Catalina always used 6061-T6 alloy and never used 6351-T6 alloy so any Catalina tank will be made from 6061-T6 alloy and not subject to the same SLC concerns and testing requirements. But many shops will still refuse to fill them as they were made prior to 1990.

 

[Scared Silly]

There are three issues - is the price right? $100 is at the high end of the price range for a used Al cylinder.

Second issue, it is made from AL6351. Yup they have a bad rep. If the dive industry was a wee bit more consistent in training fill operators and the whole VIP then there might not be such a problem. But because they are free to what they want you are at their whims. As such, I would not recommend buying a cylinder because of this problem.

http://hazmat.dot.gov/pubs/reports/cylinder/3al_advisory.pdf

The third issue - this cylinder was NOT properly re-qualified. Being a cylinder made from AL6351 it should have been eddy tested and marked with a VE after the hydro test date. The lack of the VE after the hydro test date indicates that the hydro test station lacks update to date knowledge regarding these cylinders.

http://accuratemfg.com/CATALOGS/Architect Catalog Web Current.pdf