little help...tank fails and destroyed

[PhilEllis]

I seriously doubt a relatively new 6061 cylinder had neck cracks. N

I also seriously doubt there were cracks. I DON'T DOUBT that the hydro facility THOUGHT there were cracks, maybe as a result of "false positives" from the eddy current machine. Maybe they ever rechecked the cylinder a second time. I don't know....but I can see how the hydro facility might have been led to believe there were neck cracks.

Then again, MAYBE there was a real crack.

Phil Ellis

 

[Nemrod]

If you got to this page, if not linked to already you will find some reading info on cylinder inspection specific to Luxfer cylinders.

Luxfer: Downloads

I would more likely find Big Foot sitting in my living room when I get home than that tank had a crack in it, just not really plausible to me given the rarity of 6061 neck cracks.

N

 

[Nemrod]

Luxfer: Technical Bulletins: August 1, 2002

and from Luxfer:
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10. If Luxfer 6061-alloy cylinders are not susceptible to SLC, why has Luxfer exchanged 6061 cylinders that have been reported to have cracks?

After the introduction of eddy-current technology, Luxfer received reports of cracking in 6061-alloy cylinders. We accepted returns on about 1,200 of these cylinders to conduct extensive tests. Not a single cylinder was found to be cracked.

On Luxfer 6061-alloy cylinders, eddy-current devices sometimes show harmless "indications" that lead to "false-positive" readings for SLC.

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I am not PST rated but I do have Level II NDI training. The only likelyhood I feel is reaosnable is that the facility dmaaged the threads and did not want to eat the cost of the tank. As well, if the valve had been installed incorrectly by over torquing it then perhaps the threads (not the neck or shoulder) could have been cracked.

Somebody owes you a new tank IMO unless they can show the detailed results and provide reasonable explanation and even then I am highly suspect they are at fault, not the tank.

N

 

[fppf]

Yeah, they did not follow proper proccedure, and they should pay for it.
If a tank fails, they are to "X" out the numbers on the tank. This will indentify the tank to anyone that would fill it, it failed.

This is to keep the tank intact for future inspection, IE if you sent it back to the mfgr for warrenty.

 

[Nemrod]

My last post in this topic but when you install a valve into a scuba tank you do not need to put a 12 foot cheater bar on your Harbor Freight monkey wrench and then twist until smoke comes out of your ears. Hand tight and then a little bit is all that is needed to compress the O ring, once the valve has bottomed against the shoulder you are loading the threads up. Usually about an additional 1/8 turn (or use a torque wrench with a crows foot). When using a torque wrench so as not to use the equation for correct torque with an adapter---install the adapter at 90 degrees to the wrench--in this manner the applied actual torque is the same as set torque on the dial of the wrench.

N

 

[NOVIZWHIZ]

JUST as an update - I called the Company - Stallion Air out of Cedar Falls, NC - guy I spoke to agreed that they should NOT have killed the tank without checking with me - took my address and promised to "hook me up with a replacement". Sounds good - but I've been around wa-ay too long to believe everything I hear and very little of what I see... Thanx for the help guys! I'll stay on this!

 

[Web Monkey]

JUST as an update - I called the Company - Stallion Air out of Cedar Falls, NC - guy I spoke to agreed that they should NOT have killed the tank without checking with me - took my address and promised to "hook me up with a replacement". Sounds good - but I've been around wa-ay too long to believe everything I hear and very little of what I see... Thanx for the help guys! I'll stay on this!

I'll bet they'll take care of it.

Generally when a company stands right up and says they messed up and will take care of it, they do.

Terry

 

[PhilEllis]

Luxfer: Technical Bulletins: August 1, 2002

and from Luxfer:
---------------------------------------------------------------------------------------
10. If Luxfer 6061-alloy cylinders are not susceptible to SLC, why has Luxfer exchanged 6061 cylinders that have been reported to have cracks?

After the introduction of eddy-current technology, Luxfer received reports of cracking in 6061-alloy cylinders. We accepted returns on about 1,200 of these cylinders to conduct extensive tests. Not a single cylinder was found to be cracked.

On Luxfer 6061-alloy cylinders, eddy-current devices sometimes show harmless "indications" that lead to "false-positive" readings for SLC.

----------------------------------------------------------------------------------------
I am not PST rated but I do have Level II NDI training. The only likelyhood I feel is reaosnable is that the facility dmaaged the threads and did not want to eat the cost of the tank. As well, if the valve had been installed incorrectly by over torquing it then perhaps the threads (not the neck or shoulder) could have been cracked.

Somebody owes you a new tank IMO unless they can show the detailed results and provide reasonable explanation and even then I am highly suspect they are at fault, not the tank.

N

I don't think there are any of the original Visual Plus or Visual Eddy machines, of the type/generation referenced in that link, remaining in service by any serious operators. I know I have one that is in perfect working condition and looks like new. Unfortunately, it has been removed from service. The state of the art when hydro stations were encumbered with eddy current inspection of 6351T6 was the Visual Eddy 3 machine, one that Luxfer themselves says is suitable for inspection of 6061. Since the Visual Plus 3 was the state of the art, I expect that is the machine purchased by most of the hydro facilities that now use the VE stamp required for 6351T6 cylinders and also used to test almost all 3/4-14 NSPM aluminum cylinder necks.

Phil Ellis

 

[Nemrod]

Phil, did you return that cracked 6061 tank to Luxfer, curious as to their take on it? Thanks for the info.

N

 

[DennisW]

It's been a few years since I completed my inspection course, so I beg forgiveness for the eddy current tester mistake. However, 6061 tanks do not have to have an eddy current test. I suppose a shop can make any rules they want for an inspection, but I don't have to use them either. Eddy current testers are only as reliable as the person that is trained or not trained to use them. And, they are not fail proof. There is always the chance of a false positive. I have never signed a paper allowing anyone to destroy a tank. Never will either.