New DOT Hydro Requirements?

[deepstops]

it's probably the older alloy. You wouldn't find a shop in the whole state of florida to fill one of those. (Exceptions, feel free to chime in!)

My LDS will fill 6351 tanks but only if they do the VIPlus or VIP+ (whatever it's officially named).

Personally, knowing what the destructive capability an AL80 possesses and the seemingly high incidence of crack development right after hydro testing, I would turn it into a doorstop.

 

[mike_s]

yeah... I used to think that 6351T tanks were ok if they were inspected properly, then I saw one that cracked at my local shop.

with the fact it could have killed someone, I now understand why they don't fill them anymore.

it's a 20 year old aluminum tank. time to turn it into a table lamp.

 

[WD8CDH]

Properly tested, 6351 tanks are safe but it's just not worth the hassle to deal with.

 

[mike_s]

Properly tested, 6351 tanks are safe but it's just not worth the hassle to deal with.

I used to think the same thing, but the one I was talking about that cracked had just passed hydro and vis at the hydro facility. (at a hydro facility where they have a guy who knows what he's doing).

Then the LDS VIS'd it before the initial fill after hydro. during the first fill, a tiny crack started in the neck of the cylinder and vented. (the tank did not blow). They evacuated the building, turned off the air, and let the cylinder drain on its own.

luckily the cylinder did not explode and luckily no one was injured because of this, but if they kept filling it to 3000psi, it most likely would have.

so here we have a case of a properly tested cylinder cracking after hydro and inspection. so it does happen. maybe not often, but enough that it's not worth exploding one and hurting someone for a used, 20 year old, $50 cylinder.

maybe some of them are safe... but some are clearly not.

 

[Hallmac]

but she did say that two of the first ten they did failed it.

Anyone know about this, please...?

If they are using the new Visual Eddy unit be aware it is giving off a ton of false positives. When I spoke to Nicole at Luxfer a couple of weeks ago they were being hammered with them.

 

[DandyDon]

Ok, I just got hold of her on her cell. Now she is the store manager and retail spokesman with her hubby being the Instr and tank examiner among other things. Works well for them generally, great folks & shop, but sometimes she does not have all the detailed answers on what he is doing.

And there is confusion here, so I have asked they not inspect this one until they can get me a link to more info. Her understanding is that it's a new DOT requirement for all tanks that need to be hydroed also be Visual Edded, but of course it bothers me that none of y'all have knowledge of any such change.

I did confirm that it is not a 6351. If that had escaped my notice before, I wouldn't want to bother with it; I'd voluntarily save the valve and junk the tank, but it's not.

I have aksed her to get me the details from the tank as well, or just send it back to me if she doesn't have time - either way. I think I'll contact the manufacturer when I get that info, too.

 

[Scared Silly]

DD, some people, based on the literature from the mfg of the eddy current devices which states that the eddy current test can be be used on any Al cylinder are doing just that - doing it on all Al cylinders. However, the DOT rules (posted below) are only for cylinders made from AL6351.

Hazardous Materials: Aluminum Cylinders Manufactured of Aluminum Alloy 6351-T6 Used in SCUBA, SCBA, and Oxygen Services--Revised Requalification and Use Criteria | Federal Register Environmental Documents | USEPA

This is probably the confusion. If they are confused on this point you might politely ask them when they did their last cylinder inspection refresher course. This point was hammered in years ago when I did my refresher course with PSI Cylinders.

 

[Leadking]

Going back in time (by the way I personally helped dive stores ship thousands of 6351 cylinders back to Luxfer) I read the DOT report on catastrophic failures of 6351 cylinders. In the report it stated in every instance of the catastrophic failure (explosion in fragments) that the crack(s) had been in place for years. The report details how the examination of the metal under an electron microscope showed the penetration of oxidization into the exposed aluminum from the crack and calculated the time of exposure. In every case the time was well over five years, which means that every failed cylinder had gone through one hydro cycle. This is why the DOT instituted the Eddy current protocol now used. Please do not confuse a crack and leaking with a catastrophic failure. As hard as it may be to understand, ALL tanks, alum and steel, are designed to crack before fragmenting.

I have a great deal of confusion dealing with the various boards as they discuss the abuse they heap upon cylinders (crash filling, overfilling, etc.) but are ready to jump on the hysteria bandwagon without all the facts. 6351 cylinders do crack, but with the current testing methods and proper tank handling, should be safe.

 

[DandyDon]

Okay, talked with my LDS today. They really are super folks, and I haven't spent any real money there in years, so I always appreciate them even more in taking care of me like they do.

But I am dealing with the wife/store manager, who gets her info from the hubby/Inst & tank examiner, who gets his updates from I don't know? (What's on second; Who's on first!)

Somewhere along the exchange of info, confusion happened, and they now tell me that mine does not need the extra Visual Eddy - only the older ones. She was not clear on details, but thinks it's for tanks made prior to early 90s. I suggested it sounded like just the 6351s, and I would suggest they not even touch those! She did say that the two they've had fail were 6351s that they didn't notice were such until they'd failed.

Anyway, for now - no need on mine after all. Thanks again for the help as I was working with reduced info and communication lines.

 

[mike_s]

the two they've had fail were 6351s that they didn't notice were such until they'd failed.

.

their communications issues and the fact that they didn't know/reconize a 6351T alloy tank "until it failed" doesn't instill confidence in me with that shop....