1989 Luxfer cylinder VIP refusals

[Stu S.]

To make a dealer-operated safety program work for 6351's, VIP accuracy nationwide would have to be near-perfect. It isn't.

VIP became practice due to rusty steel tanks, as aluminum was not on the scene. The inspectors looked inside with little lights and determined "OK" or "rusty". The possibility of passing a bad one was small. It was something any dive shop could do.

Today, it is more than peeking in there for rust. Correct inspection of an aluminum tank per 2008 standards may be above the ability of some dive shops and their employees. My local guys appeared to be doing it right. Other folks don't have that attention to detail. And... there is no system for "inspecting the inspector".

Since the process is not perfect, the way to safety is to improve the quality of the items going into the inspection process. That means compressor owners choose to get 6351's out of circulation, and avoid a bad one labeled as good.

In these situations, the consumer pays the price. Good tanks get scrapped and replaced to get the few bad ones gone too.

 

[mictrik]

Thanks for not doubting me Vance. I will reply to those who ridicule me by simply stating that through the years I have had the following happen at various dive shops:

1) Tank needs roll after hydro even though it was stored with air in it (almost full) and not used after hydro. Hydro done September 05, Inspected May 06 and it had flash rust... shouldn't need inspection but I check anyway and most dive shops try to tell you that they need to re-inspect it as if the Hydro tester was less qualified. In this case that may have been true as the hydro facility was shutdown by the DOT. Wonder why?? I found out by looking at the hydro facilities stamp and contacting the DOT. The inspector who shut them down was very informative. The kicker is that I paid extra by leaving the tank at my dive shop who sent the tank to this facility. I usually bring the tanks for hydro myslef and would always check for any violations with the DOT before going to a new or unkown facility but I let someone else do it and paid... So I paid the premium for dive shop hydro (LOL), then I paid them for a VIS which probobly was not done (why should it? after all it’s part of a hydro) and then I have to pay for a roll… Nice!

2) Had my superflow hoses switched during an overhaul, apparently someone wanted the length of hose that was on my reg. A very respected Scubapro technician from a shop in NYC told me that he had heard of this happening because the superflow hose that was on my reg was not made the same way anymore. Apparently some people who know think the rest of us do not so they just swapped it out without telling me; unfortunately I noticed too late.

3) Had the Mk10 plus upgrade pushed on me which did nothing but increase the rate that I experience IP creep. Haven’t had problems recently but Scubapro seemed to have changed the seat material/ shape.

4) I have marked tank O rings that should be replaced during inspection to find that they had not but the inspector still claimed they had...

5) Had tank forgotten while being filled, compressor was on and the scuba shop owner was busy selling gear. Tank was a 3500, it was completely under water and pressure was at 4350 when I got to it; don’t ask me why the burst disk did not fire...

5) Had knob on my G250 bent by 5 star authorized Scubapro shop. This was the last straw (about 7 years ago) after this I began keeping my own parts to include: balance caps, extra knob for G250, Lever, spring and everything else but a new air barrel.

6) Lets not forget all the short fills, I could care less about your compressor wear and tear it's called a business expense! I have them too! When you pay an extra dollar for a 3500PSI tank to the tune of a $9.00 per fill I expect at least 3500Psi (I repeat, at least 3500) when at ambient water temperature. That usually means I should be at 3600 to 3800 leaving the shop, period… In Europe 300 bar is common and I found out from a DOT inspector that these tanks CAN be DOT certified for fill by DOT stations in certain international airports. I would love to bring a couple Poseidon 300 bar tanks over but I can t even get a 3500 fill.

Many dive shops have become next to useless for me. The level of knowledge from the shop rarely adds to mine anymore and the amount of dis-information provided is just too high. Few dive shops keep a full assortment of a product line in the shop to try, touch and feel prior to purchase (I know, it’s expensive to keep inventory). I understand it’s a business, the bottom line and all but don’t try to make up for tough business fundamentals (on-line dealers) without providing exceedingly better service. A short fill not better service nor is the BS I hear about the latest reg and BC’s and the benefits over my “outdated” reg's (I have old Scubapro G250’s, R109’s G200B, D350, a Poseidon Jetstream and a SP Pilot). I have many more mishap stories than those listed above but I won’t for further bore you (or me) with them. Just please understand that some of your customers are design engineers, experienced technicians and or/very precise tinkerer’s who possess more than enough skills to do a perfect regulator overhaul each time everytime on their own gear. Some people like me do things themselves because we want it done right and right means perfect. Perfectly cleaned, perfectly lubricated and perfectly adjusted… As far as tank inspections go I have always checked them BEFORE I had them inspected now I am just sick of that so I will place a sticker on them myself. After all, how many courses in metallurgy have most tank inspectors had? Heck, most of them don’t even take a DEMA inspection clinic… Yes, I know many are great and I really appreciate it when I deal with those few but it is getting too far and few between.

 

[james croft]

I spend a hell of a lot more time inspecting my own tanks as opposed to my LDS. I own about 40 cylinders of all descriptions, from large bank cylinders to 6 cf cylinders. I have been through TDI and PSI inspection courses and have invested in the proper tools to do a complete inspection. I did this to save money and for convenience and for my safety. I have seen several LDS shops stick a VIS on a tank that they inspected in a couple of minutes. I have spent a half-hour going over a lot of my cylinders. I have found some of my tanks to be suspect and turned them into a pressure vessel or wind chimes. I would hope a LDS shop would honor my stickers. Especially the shop that taught my visual inspection courses.

 

[rstofer]

This has been an interesting thread! I have an early Luxfer Al 80 that SHOULD be made of 6061 according to the DOT published list of tanks as it was manufactured in August 1988, after the DOT deadline of January 1988.

Luxfer, on the other hand, says that some 1988 tanks were also made of 6351 and to call Customer Service to determine if the tank was made of 6351 alloy. Clearly, my LDS is not going to call every time I bring the tank in for a fill. According to DOT, they shouldn't have to. I think I'll call tomorrow just for giggles.

If it is 6351 alloy, I'll junk the tank. I don't want the accident here or at the fill station.

It's funny how steel is viewed as the panacea. When I was in Singapore (1988), we could take aluminum tanks to Malaysia but not steel. They viewed internal rust as more of a problem than aluminum cracking.

Richard

 

[mike_s]

There is one person at Luxfer that deals with 6351 issues.

have her verify the serial number as not being 6351 alloy and see if she'll send you a letter stating that. That way if you get it filled anywhere, you have some verification you could show them.

yeah... a lot of hassle, but if you really want to keep the tank, thats an option.

 

[rstofer]

I didn't ask for a letter but I did call. My June '88 Luxfer Al 80 is made of 6061. Nothing changes, it will still need eddy current testing because it is earlier than 1989. As it was explained to me, all aluminum tanks will require eddy current testing when they are 20 years old.

Apparently steel tanks won't require this additional testing.

It is not my understanding that I require eddy current testing during visual inspection next year. We'll see.

I paid about $140 for the tank (maybe...) 20 years ago. It's time to junk it just on general principles. I'm giving up on aluminum tanks anyway.

Richard

 

[Ken abucs]

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.

I am not an alarmist. I do due diligence and research on most issues related to my business. I try to make my decisions with deliberation. I did not adopt a policy of refusing these cylinder fills just to "sell another tank". Heck, I make more money from the inspection and air fill than I do from the sale of a new cylinder. When I refuse to fill these older cylinders, my customers certainly can take their business elsewhere if they disagree. However, they would not be moving because they are leaving an uninformed and unthinking dive center, but would be leaving one who actually has thought this through and is acting out of reasonable precaution.

Phil Ellis

I'm not a metallurgist, but isn't that the whole point of the 6351 alloy, to fail in a "safe" and predictable manner. The problem with 6061 is that it would fail catastrophically. I too would be very concerned (understatement of the year) to see a tank leaking from a crack, there's no indication that any of the failed 6061 tanks gave this type of warning. 6061 tanks will just explode.

I think the two anecdotes above of how the 6351 tanks failed demonstrate how a tank is supposed to fail. Is there a metallurgist on the board that can discuss this further.

I'd also like to add that I own steel cylinders, so I have no vested interest (other than my own safety).

Ken

 

[PhilEllis]

I'm not a metallurgist, but isn't that the whole point of the 6351 alloy, to fail in a "safe" and predictable manner. The problem with 6061 is that it would fail catastrophically. I too would be very concerned (understatement of the year) to see a tank leaking from a crack, there's no indication that any of the failed 6061 tanks gave this type of warning. 6061 tanks will just explode.

I think the two anecdotes above of how the 6351 tanks failed demonstrate how a tank is supposed to fail. Is there a metallurgist on the board that can discuss this further.

I'd also like to add that I own steel cylinders, so I have no vested interest (other than my own safety).

Ken

By DOT standards, all scuba cylinders should be designed to "leak before burst". This is an essential element of the design and testing process. The problem is.....some cylinders have done the opposite...they have burst before leaking. Most post-accident evaluations revealed that the alloy was 6351T6. This revelation resulted in years of test and evaluation and the eventual discovery that these cylinders were prone to sustained load cracking in the neck area. For this reason, cylinder manufacturers moved to 6061T6 alloy to eliminate this possibility.

I know of no evidence that 6061T6 is designed to do anything but "leak before burst". There is also no practical evidence that 6061T6 has any failure mode other than the one that is designed in......leak before burst. I am also lucky that the 6351T6 cylinder I described noticeably leaked before coming apart. Had that not happened, we could have had an outcome that was bad.

Phil Ellis

 

[Stu S.]

Is there a metallurgist on the board that can discuss this further.
Ken

Yes. I worked in the business. The main objective was no failures at all. If the vessel failed, it should not fragment. For aircraft applications, part of our testing sometimes involved firing a 50 cal. machine gun round right at the vessel. It had to remain intact after puncture.

 

[Ken abucs]

For aircraft applications, part of our testing sometimes involved firing a 50 cal. machine gun round right at the vessel.

You're in for it now. You're going to get bombarded from folks who want to see the video.