Scrapped an Alum 80 6351 tank today

[Boiler_81]

I have even had shops in FL refuse to fill a steel 72 because of the manufacture date was before 1990. Some of the ignorance around this issue is truly mind blowing.

 

[teknitroxdiver]

Some of the ignorance around this issue is truly mind blowing.

 

[Rick Christ]

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

If the dive shop has that attitude, that is a sign that they are incompetent, or lazy or doesn’t care and is scamming you and you should stay away from them.

 

[snowdog61]

Ignorance is typically fixable but again, their shop, their rules or at least how they wish to apply the actual rules. Yes, I vote with my wallet and that tank only gets its vis when we are down in Tavenier for opening week of lobster season. It's my only 'air' tank as I prefer HP100s

 

[Rred]

I can't help thinking that $7.40 tank could have been put to good use as a gag prop. You know, fill with sand, add an equally defective regulator and a small metal box with a coin slot on it. Put a sign on the tank "Insert quarters, 4 quarters for 3 minutes" and then install the tank on a popular wreck.

Sit back and watch how many divers try to use it. Or take it.

 

[DA Aquamaster]

We have a local shop here that is otherwise fairly intelligent in it's operations but has an owner who has just decreed that 6351-T6 tanks shall not be filled.

The irony here is that I visually inspected one of the shop owner's exempt steel tanks and found numerous pits in the side walls that were bordering on being excessively deep - some of the worst pits I've ever seen in a scuba tank brought in for routine service. At some point in the past, someone ion the shops tumbled the bejeezus out of it to remove the rust and rounded the edges of the pits. That makes it even harder to accurately determine the depth of the pits. Given that it's difficult to measure these pits precisely, and given the large number of very significant pits, I recommended he condemn the tank - or at a minimum have it sent out for hydro test and let a RIN offer a second opinion (and any RIN with a lick of common sense would condemn it).

He did neither, and put it back into service. Dumbest. Move. Ever. I ain't filling it - no way in hell - and I advised the tank monkeys there not to fill it either.

The reality is there has been no catastrophic failures of properly inspected 6351-T6 aluminum tanks since the initial 18 month eddy current protocols were first implemented around 2002, nor the final 5 year eddy current requirement at re-qualification adopted by the DOT in January 2007. Thats 0 out of 25,000,000 tanks.

If it's been re-qualified with an eddy current inspection denoted by a VE stamp, it's good to go.

Unfortunately many dive shops arbitrarily use a 1990 cut off date for filing aluminum tanks, including Catalina tanks that were never made from 6351-T6 alloy, probably because they are too lazy to train their staff to refer to the published list of tanks made from 6351-T6 alloy. Or perhaps they see this as a way to sell more tanks, despite the very low margin on scuba tanks.

----

Personally, I just picked up a pair of Luxfer AL 80s made from 6351 T-6 alloy and I'm taking them down to FL on my next trip to get re-qualified (the RIN the shop here uses is not equipped for eddy current inspections). I'll have no qualms filling them on my own compressor.

 

[DA Aquamaster]

I can't help thinking that $7.40 tank could have been put to good use as a gag prop. You know, fill with sand, add an equally defective regulator and a small metal box with a coin slot on it. Put a sign on the tank "Insert quarters, 4 quarters for 3 minutes" and then install the tank on a popular wreck.

Sit back and watch how many divers try to use it. Or take it.

I agree. There are lots of uses for retired tanks. Cut the top off and use it to display regulators, then use the bottom for a wind chime, umbrella stand, trash can - what ever.

$7.40 is a poor price in exchange for something with a lot more market potential to someone.

Unfortunately I think too many people get off on the idea of scrapping the tank, like they are doing humanity some kind of favor.

Muppets.

 

[luscioman]

For me taking the $7.40 was a good exchange. I currently have 29 tanks sitting in my garage and i need to trim that number down before my wife starts putting them outside. This tank had no value for me and it didnt make sense to sell it away. In addition the outside cosmetically looked very poor and would not display well.

 

[guruboy]

For me taking the $7.40 was a good exchange. I currently have 29 tanks sitting in my garage and i need to trim that number down before my wife starts putting them outside. This tank had no value for me and it didnt make sense to sell it away. In addition the outside cosmetically looked very poor and would not display well.

So put some outside? They're not going to rust or anything.

 

[2airishuman]

I visually inspected one of the shop owner's exempt steel tanks and found numerous pits in the side walls that were bordering on being excessively deep - some of the worst pits I've ever seen in a scuba tank brought in for routine service. At some point in the past, someone ion the shops tumbled the bejeezus out of it to remove the rust and rounded the edges of the pits. That makes it even harder to accurately determine the depth of the pits. Given that it's difficult to measure these pits precisely, and given the large number of very significant pits, I recommended he condemn the tank - or at a minimum have it sent out for hydro test and let a RIN offer a second opinion (and any RIN with a lick of common sense would condemn it).

He did neither, and put it back into service. Dumbest. Move. Ever. I ain't filling it - no way in hell - and I advised the tank monkeys there not to fill it either.

You saw the cylinder, I didn't. That said, pitting has to be awfully bad before it exceeds the threshold. I've seen some cylinders come back from hydro shop with a stamp that I would never have thought would pass.

The reality is there has been no catastrophic failures of properly inspected 6351-T6 aluminum tanks since the initial 18 month eddy current protocols were first implemented around 2002, nor the final 5 year eddy current requirement at re-qualification adopted by the DOT in January 2007. Thats 0 out of 25,000,000 tanks.

If it's been re-qualified with an eddy current inspection denoted by a VE stamp, it's good to go.

There are, in my opinion, three problems with using 6351 cylinders. There is a safety problem, a cost problem, and a practical problem.

The safety problem is that the VE inspection process is not believed to be perfect. Some cracks will be missed. The sustained load cracking problem is cumulative over the amount of time the cylinder is pressurized. A growing number of cracks have been found over time. This is not a problem where we will eventually "weed out" all the bad cylinders, on the contrary, more cracks are going to be found every year as long as the population of 6351 cylinders in use remains large. The risk of missing a bad cylinder, therefore, grows over time. It is a risk that many would choose to accept, but one I have decided to avoid.

The cost problem is that VE inspections cost money and make these cylinders uneconomical. New AL80s are typically sold with valves. Prices do vary around the country and from shop to shop, but as a benchmark, DGX charges $149 for an AL80 with a new Thermo provalve with the valve itself be worth maybe $50. So the new cylinder with a fresh hydro and VIP is a $100 purchase. When contemplating what to do with a 6351 cylinder that is out of hydro, well, the hydro, VE, and VIP are going to cost maybe $50 all together, and then every future hydro is going to be typically $20 more than it would be for a new cylinder. Depending on who does your VIPs the VIPs may cost more. Or you can scrap it and get $10. At best you save $50 the first year over a brand new cylinder, and loose money over the long run.

The practical problem is that, like it or not, there are places that won't fill these, whether their logic is sound or not.