Scrapped an Alum 80 6351 tank today

[luscioman]

So probably like most of you friends of mine that know I dive occasionally give me gear they are not using any more. Last week I was given several Alum 80 tanks all out of hydro. So one of them was from 1988 and was a 6351 alloy. To save any headaches i just scrapped it. The tank looked horrible and the valve was garbage as well. I got .20 per pound for 37 pounds so i got $7.40 for the tank. I though i would have gotten a little bit more for the tank but that was it. For me that i own more than 10 tanks i had no desire to cut it and make it a bell or anything like that.

 

[iamrushman]

how much would a bell or ashtray be worth?.... i guess..about $7.40..

 

[guruboy]

A Luxfer S80 from 1988 is not 6351 alloy. Sorry to be the bearer of bad news.

Dates when Luxfer changed its aluminum alloy from 6351 to 6061

 

[luscioman]

Interesting here is what PSI listed. Either way the tank was not going to get a hyrdo and nobody would fill it here.

PSI-PCI - A short Review of 6351 Alloy Aluminum Cylinders

Sustained load cracking (SLC), a metallurgical anomaly, occasionally develops in 6351 aluminum alloy high-pressure cylinders. As the name implies, SLC usually occurs in cylinders that remained filled for long periods of time. US manufacturers that used 6351 alloy included Luxfer Gas Cylinders (made prior to May 31, 1988), Walter Kidde, Cliff Impact, Norris Industries (SP6688) and Kaiser (SP6576). The permits for both Norris and Kaiser have expired and those cylinders are no longer approved for use in the US. Luxfer stopped using 6351 alloy by mid 1988 and now provides a complete listing on its web site of dates when various cylinder models were changed to a proprietary 6061 alloy. Catalina Cylinders began making aluminum cylinders in 1986 using a 6061 alloy that is NOT susceptible to SLC.

 

[guruboy]

That's because PSI made a blanket statement for ALL models of tanks.

I am referring to Luxfer S80 ONLY.

 

[2airishuman]

I got .20 per pound for 37 pounds so i got $7.40 for the tank.

You did right. I recently scrapped an aluminum cylinder under largely similar circumstances. Many places just won't fill them, especially in Florida. I could get fills here, but some shops require an annual eddy current test, and it doesn't make economic sense to do that, over the long term, or when considering a cylinder that needs hydro and valve work.

The safety situation with these cylinders is unclear to me. The received wisdom is that the visual eddy tests weed out all the bad cylinders and prevent accidents. They have certainly helped. I'm not convinced that they provide an equivalent level of safety to the new alloy.

Scrap prices here are somewhat higher.

 

[guruboy]

You did right. I recently scrapped an aluminum cylinder under largely similar circumstances. Many places just won't fill them, especially in Florida. I could get fills here, but some shops require an annual eddy current test, and it doesn't make economic sense to do that, over the long term, or when considering a cylinder that needs hydro and valve work.

The safety situation with these cylinders is unclear to me. The received wisdom is that the visual eddy tests weed out all the bad cylinders and prevent accidents. They have certainly helped. I'm not convinced that they provide an equivalent level of safety to the new alloy.

Scrap prices here are somewhat higher.

Except what he scrapped wasn't 6351.

 

[2airishuman]

Except what he scrapped wasn't 6351.

::shrug:: It doesn't matter much if the dive shop won't fill it without a VE because it has a 1988 date.

 

[Scared Silly]

::shrug:: It doesn't matter much if the dive shop won't fill it without a VE because it has a 1988 date.

Except a 6061 cylinder does not need a VE inspection let alone a VE stamp. That is all ignorance and laziness on the shop's part.

 

[snowdog61]

Sadly what I have seen here in Florida is that shops won't fill anything aluminum if it is earlier than 1990. It is a blank cut-off date. I have a 6-88 build date Luxfer S80 tank that had only 1 VIP performed before it was retired with 500psi in it sometime in 1989. It had been stored inside the house and was given to me in like-new condition. Passed hydro with no issue (I requested VE just because - though I knew it was not needed) Took me 5 shops before I found one that would fill it. AND that was even a struggle even though I provided all the paperwork showing that this was a 6061 alloy tank and not the 6351. All you'd hear was "Too old. Can't be filled. SLC. yada yada" That tank came with an equally nice, earlier build tank that was 6351 - I didn't even bother to try and get that one back in use as I knew I'd be fighting ignorance all the way. Even if it is 6351, a proper eddy current at hydro (VE stamp) and thread inspection at visual should be sufficient to fill it. Yes, I understand that the shops can make their own rules and apply what they think is right - Pressure vessel failures are surely nothing to be careless about. But these defects show themselves before total failure occurs - that's why you do the tests & inspections.

Funny(?) thing is though, if you go outside the country, all this Visual Inspection Program and Hydrotest Schedules mysteriously go away. I make an effort not to check the tank stampings when I travel as I know I won't be happy. Scary stuff there