Used tank info

[cgvmer]

I have searched the forums, and after reading a dozen or so have not found the answer to the question of how to identify tanks that can no longer be vis'ed or hydroed?

I was hoping for something showing the identifying numbers on the tank.

 

[captain]

The only tanks that can't be hydroed are those that have already failed a hydro. There is no age limit on a steel or aluminum tank as long as it continues to pass hydro, eddy current and visual inspection.
The only other case are tanks manufactured under an exsemption certificate and the tank manufacture does not renew the exsemption when it exspires.

 

[cgvmer]

Thank You. I had heard that older AL tanks were no longer being hydroed

 

[oxyhacker]

Actually, there are, mostly tanks that were made under an exemption many years ago, that the manufacturer let the exemption expire when it lost interest in the scuba market or went out of business, back in the dark ol' ages before people realized that it was possible for someone other than the manufacturer to renew the exemption if the manufacturer didn't.

Probably the most common of these is the Norris E6688 aluminum exemption tanks. Norris let the exemption expire when they go out of the scuba business, and thousands of the tanks became orphans, illegal to fill or hydro. BTW, we looked into renewing the exemption but were told it had been too long since it expired. Ironically, Norris almost did the same thing again with their recent steels when they decided to leave the scuba market again! Kaiser also made some SP6576 tanks which the expemption for has long since expired. However, all these tanks were made a long time ago, and in not great quantities, so you are very unlikely to come across one. Any Luxfer or Catalina tank is legal to use and hydro, assuming it passes inspection.

There are rumored to be a few others like the Kaiser SP6020 that had the exemptions revoked because the tanks proved unsafe in service, but this is hard to confirm. A lot of shops will tell you the E6688 Norris tanks were pulled because they were unsafe, but they were not (at least, not any more than any of the other 6351 tanks) - it was just a paperwork thing.

Note that just about all these tanks were early exemption or special permit aluminum tanks, made before the DOT extablished the 3AL specification for aluminum tanks. Most of the aluminum exemption tanks, including E6498, SP6478, E7042, were grandfathered into the 3AL specification when it was established, and should have been restamped 3AL at the next hydro, however occasionally you will find one that wasn't. While these are all still legal, most of them are 6351 "bad alloy" tanks and not a good buy.

 

[spectrum]

As a practical matter any aluminum cylinder is becoming useless at 20 years old.

Technically the problem is related to the 6351 alloy cylinders sold pre 1988 by Luxfur and a few other such as Kidde. In reality there is a growing tendency in the industry to blackball any old aluminum cylinders and simply refuse service. One local shop offers to do a visual inspection for $119. !

You can look into local practices but this is getting tighter at a fast pace. What will be serviced this year may be scrap next year. Technically any of these cylinders can be kept in service with an eddy current test and normal inspections but the layers have the shops running.

Steel is pretty much timeless.

Pete

 

[truck1]

I agree with you Pete. Its the local shops and boats that are blackballing the 6351 cylinders. I spoke directly with Luxfer, and also have the paperwork from the CGA (Compressed Gas Association) and all say that as long as a cylinder passes a hydro, AND a VE, then the service life of a 6351 cylinder is timeless. Once one fail either or both then they are to be condemed. Most shops are ignorant or deliberately ignoring the ruling to sell new tanks. There are a few and I stress few such as Fill Express, that have had an issue with a 6351 and wont work with them. The vast majority are going by rumor and inuendo.

I had one shop try and tell me they were exploding on peoples backs underwater. Therer has never been a tank failure while in use or underwater.I have the failure paperwork also. There has only been about 18 failures in about 15 years give or take.

 

[deepstops]

Most shops are ignorant or deliberately ignoring the ruling to sell new tanks. There are a few and I stress few such as Fill Express, that have had an issue with a 6351 and wont work with them. The vast majority are going by rumor and inuendo.

I just want to clarify this statement. FE will fill 6351 tanks provided FE did VIP work.
Fill Express -- Frequently Answered Questions About Filling Aluminum 6351-T6 SCUBA Cylinders

That being said, FE only applies that policy to 6351tanks as opposed to some shops just saying "every tank made before XXXX should be condemned".

 

[Scared Silly]

IIRC some of the old Norris were round bottom Al cylinders. Any round bottom Al cylinder no matter the mfg, material, exemption, special permit can no longer be legally hydrostatically tested. Although I own a 6351Al cylinder I would also heed the comments on buying one. The hassle may not be worth it.

 

[captain]

IIRC some of the old Norris were round bottom Al cylinders. Any round bottom Al cylinder no matter the mfg, material, exemption, special permit can no longer be legally hydrostatically tested. Although I own a 6351Al cylinder I would also heed the comments on buying one. The hassle may not be worth it.

The round bottom aluminum cylinders were made for the Navy and were never ment for the civilan market. They were made of 6160 aluminum tubing. They are stamped 3000psi WP (working pressure) and 5000psi test pressure They have no ICC or DOT specification stamp on them.

 

[cummings66]

Yup, and that's the issue there. No stamps no tests. They never were supposed to by hydro'd in the first place. In my PSI inspection course they had one of them as an example of mistakes being made. It had numerous hydro stamps and VIS stickers on it, none of which should have been done. Point of fact the stickers should have been removed as well to see under them, it was covered in them to the extent it looked like a walking billboard. And it wasn't from the same dive shop, it was numerous dive shops.

A hydro facility must abide by the govt. regulations, a VIS inspection for the scuba industry isn't law and so you could argue that you could do a VIS on them, but the hydro could not be done. I myself would not do a VIS on one of these cylinders either, I figure if the hydro facility can't test them then I won't VIP them. Many insurance companies for dive shops require some sort of training and safety program in place for fills to get decent coverage rates (assuming the LDS cares about insuring) and then you get insurance restrictions which require training and compliance with standards. I'm on file at a LDS because I've taken the training and it helps them get lower insurance rates. There really isn't a law that's standared for scuba gear, but if it was used commercially then there is a law there. Go figure.