1989 Luxfer cylinder VIP refusals

[redacted]

I first saw the "No Al prior to 90" rule on a Gulf-Diving live-a-board a few years ago. But they were using volunteer temporary tank fillers so I can see the simple rule in that case. Plus they provided replacement tanks for free for any effected divers so there was no question about motives.

Shops should have a much more stable environment and sufficient opportunity to screen and train employees that such simple but biased rules should be unnecessary. Perhaps the shop could add an additional sticker to record their verification that a pre-'90 tank is not the 6351 material and can be filled by that shop. It is just silly to be denying fills of older Catalina tanks unless the reading ability of the tank filler is in question.

 

[WD8CDH]

One of the things that bothers me is a discussion I had with the owner of the shop/hydro facility I worked at a few years ago.

His feeling was that the regs called for the VIP before the hydro test. That makes sense in regard to ensuring you don;lt waste time on a tank that fails the VIP. But it does nto make sense in regard to ensuring the tank is now dry and unrusted and it does not makes sense in that the tank is not inspected after the stress of the hydro.

Interestingly, this same gentleman had previously showed me a tank that had passed the VIP and eddy current inspection they got hydro tested and came out of the tank spurting water out the shoulder/neck area. Had this crack been slightly less propogated it could have concievably passed the inpsection and failed in service in the manner you encountered. The scary part is he did not appreciate the disconnect betwene the regs and the reality of the situation.

My thoughts are that annual eddy current inspections still make sense at the dive shop level and that they are best done after the hydro test, not before. Frankly if I owned a shop and knew the test facility eddy inspected prior to hydro, I'd do my own eddy current inspection on the tank p[rior to filling it.

Personally, I feel the Eddy Current test should be performed both before AND after the hydro. SLC is a slow process but the stress of a hydro can enlarge an SLC crack if already started.

I have no fear of an old aluminum tank that was Eddy Current tested within the last year IF it was not pressurized over it's working pressure since the test.

 

[PhilEllis]

Personally, I feel the Eddy Current test should be performed both before AND after the hydro. SLC is a slow process but the stress of a hydro can enlarge an SLC crack if already started.

I have no fear of an old aluminum tank that was Eddy Current tested within the last year IF it was not pressurized over it's working pressure since the test.

The incident recounted earlier in this thread had a VE performed after the hydro. It was performed by the hydro station. In addition, a visual inspection was performed, including a well-lighted, detailed look at the threads

I was the only remaining shop in my area filling 6351-T6 cylinders until slightly over a year and a half ago. We sent a cylinder out to the re-qualification facility locally and had the hydro with the required VE inspection completed (Note: This was the same week that the gentleman from RI was badly injured by a failure of one of these cylinders). Upon return to the shop, we throughly inspected the threaded area of the cylinder and found no problem. While ON THE FILLING STATION, my employee noticed the common sound of air venting. Upon inspection and checking of all of the valves and releases, he noticed that the air was venting FROM THE SIDE OF THE NECK OF THE CYLINDER. We immediately evacuated the store and I went back inside to do the shutdown and draining. We have the very cylinder in question right here in our store and have shown it to many who express interest in this situation. In fact, some other members of this board have seen it and can probably relate what they have seen. NO NECK CRACK WAS VISIBLE in the neck at inspection, but 30 minutes later.......an obvious crack, leaking air.

Prior to this incident, I was not afraid of them either.

Phil Ellis

 

[roakey]

Phil, I assume you've contacted Bill High at PSI about your failure? This rapid crack development runs counter to the entire industry's knowledge, but you have a unique set of circumstances that support your data.

Roak

 

[mike_s]

This rapid crack development runs counter to the entire industry's knowledge, but you have a unique set of circumstances that support your data.

how can anyone be sure of that statement?

I mean of the other tanks that have had this problem with substained load cracking, they either exploded while unattended, or being filled and that doesn't mean the fill person was watching the neck to see if a crack was developing. Any "unattended crack" would likely result in failure of the tank, especially filled at rated PSI.

The filler might have heard the "leak", but most likely his eyes were on the fil panel watching the PSI instead of the tank. so typically no one watches the tank.

Not all were "slow cracks" that developed as a leak. But I'm not sure how many exploded while being filled compared to ones sitting full in a corner that blew with no one around.

However, there is at least one other example in this thread of this "rapid crack development" as noted in the post by Captndale.

I would say that we have at least two exmamples of this here and prob more as not everyone is on Scubaboard and even the ones that are on Sb are not all reading this thread.

just something to think about.

 

[Web Monkey]

I was the only remaining shop in my area filling 6351-T6 cylinders until slightly over a year and a half ago. We sent a cylinder out to the re-qualification facility locally and had the hydro with the required VE inspection completed (Note: This was the same week that the gentleman from RI was badly

Had they done an eddy current test?

Terry

 

[roakey]

This rapid crack development runs counter to the entire industry's knowledge, but you have a unique set of circumstances that support your data.

how can anyone be sure of that statement?

Cracks studied after failure to date show significant oxidation on much of the crack faces, evidence that the crack existed for quite some time before the failure. This is why the industry has concluded that there is plenty of time to discover SLC before it fails. It would be interesting to let PSI take a look at the crack that Phil encountered and see what they conclude – do the faces lack oxidization, or does it show oxidation which means that the crack had existed for quite some time?

Roak

 

[PhilEllis]

Cracks studied after failure to date show significant oxidation on the crack faces, evidence that the crack existed for quite some time before the failure.

Roak

Roak, I never argued that the crack wasn't there before, during, and after the inspection. I said the crack was not detected by any of the four inspections performed on the cylinder JUST prior to filling.....a visual inspection by the hydro facility to determine if there was any gross damage that would impact the hydro, the hydro test itself, the eddy current test after the hydro, and our visual inspection here in the store.

I have no clue if the crack developed during the filling or ten years prior. I do have a clue that the four safety inspections, in two days, did not detect the crack.

Also, don't think for a minute that this is the first cylinder to pass various inspections, only to come apart during filling. While I haven't searched lately, I think there are reports of exactly this same thing happening before....in fact, as MikeS said, one earlier in this same thread.

Just a note: I am not a PSI inspector, so I would not have contacted Bill about this. However, I have the experience of probably 1000 previous cylinder inspections. I have caught cracks, during inspection, of about seven 6351-T6 cylinders and taken them out of service. This one that is the subject of my post was not detected.

Phil Ellis

 

[PhilEllis]

Had they done an eddy current test?

Terry

Yes, Visual Plus 3, after the hydro. The cylinder had been properly stamped, according to the newest standards for 6351-T6 cylinders.

Phil Ellis

 

[Tx_Jeff]

I have two tanks from '83 and two from '84, my local LDS didn't have a problem with VIPs. All four are up for hydro this year so I guess I will see how they do. I don't have a problem with fills because I do them at my fire station.