USN diver tanks, big about 80 or 90 cu. ft. with a welded plug in the bottom.

[dead dog]

I know these tanks are no good for diving.
I need then for a display I'm setting up.
Will pay a fair price for two of them.
Send an IM if you have some for sell with dimensions,

Thank you

dead dog

 

[captain]

The Navy referred to them as 90 cu/ft but they are closer to 80 cu/ft, they are 7-5/8 inches in diameter and 26-1/2 inches tall, the plug is screwed in not welded. I have a twin set I use for diving, no reason not to use them.
They are not for sale but good luck finding them. The two I have were offered for sale here on scubaboard.

 

[John C. Ratliff]

Actually, there is a good reason for not using them for diving; they cannot be legally hydrostatically tested. They were made for the U.S. Navy, and never commercially available. They were given a very limited life too. The plug in the bottom is the reason they cannot be hydrostatically tested. The Navy put them up as surplus in the 1980s, and basically got rid of them as newer AL tanks became available. I got wind of a pallet that a school district received for use practicing welding on aluminum, and found that one set was being set up for diving. I told the LDS not to refill them, and they were subsequently drilled, with the agreement of the diver involved. I visited the school and made sure all the others in this lot were also drilled. (At the time, I was a Safety and Health Consultant for a workers' compensation insurance company who insured the school, and my memory says that the diver was also the welding instructor at that school.)

The photo shows these tanks in use at the U.S. Navy School for Underwater Swimmers, 1967. Dead Dog, do you need photos of these tanks like this one for your exhibit?



SeaRat

 

[captain]

John, they can be hydro tested, they just can be stamped with the testers ID symbol. I had mine tested at the local hydro facility that does all my other tanks, no stamp but a copy of the log with the test results was given to me. Now getting them filled by a shop is another discussion, but as far as their safety, if they pass the test it is not an issue. They passed with better numbers than my steel 72's. The main issue with the plugs is that some did eventually leak.

 

[imjustdave]

John on what premise did you determine they were bad tanks? Not trying to pick on you but from what I read they can be hydro tested vip etc. So I don't see a technical base's vs personal opinion.


Sent from my SCH-I545 using Tapatalk

 

[dead dog]

John, they can be hydro tested, they just can be stamped with the testers ID symbol. I had mine tested at the local hydro facility that does all my other tanks, no stamp but a copy of the log with the test results was given to me. Now getting them filled by a shop is another discussion, but as far as their safety, if they pass the test it is not an issue. They passed with better numbers than my steel 72's. The main issue with the plugs is that some did eventually leak.

The " plug " is the problem, I know that. The Navy never tested any further than to discard them. My instructor Harry Vetter got hold of a bunch and used them for training students in the early 60's. One of our classmates was able to buy two from Harry, how he did it I don't know to this day. Harry worked at the Aquatic Center in Santa Ana, Ca., where he could fill them for free ( never to the max psi ) The guy who bought them was a welder by trade and new what the weak spot was, it was the plug. He welded the plug shut from outside as well as the inside. How the hell he did the inside ( was a miracle ) I don't know. He used them ( tanks ) for many,many years, since he had his own compressor to fill them.


Bill

P.S. The lesson to this is DON"T trash and toss out any old diving gear.

 

[Luis H]

The " plug " is the problem, I know that. The Navy never tested any further than to discard them. My instructor Harry Vetter got hold of a bunch and used them for training students in the early 60's. One of our classmates was able to buy two from Harry, how he did it I don't know to this day. Harry worked at the Aquatic Center in Santa Ana, Ca., where he could fill them for free ( never to the max psi ) The guy who bought them was a welder by trade and new what the weak spot was, it was the plug. He welded the plug shut from outside as well as the inside. How the hell he did the inside ( was a miracle ) I don't know. He used them ( tanks ) for many,many years, since he had his own compressor to fill them.


Bill

P.S. The lesson to this is DON"T trash and toss out any old diving gear.

That is the worst thing he could have done. He was lucky he didn't have an issue.

These tanks were made out 6061-T6 aluminum alloy. The T6 stands for the heat treatment of the aluminum. When you weld 6061-T6 it anneal to a T1 condition (it has been shown that age hardening eventually gets it back to about a T3 condition).


It is possible to heat treat 6061 after welding, but it is a multi-step process requiring a precise oven and it often results in material distortion if the process is not controlled properly. I have never heard of any individual welder attempting this process, but it is not impossible (just impractical).

There are many reasons why the DOT does not allow welding on there pressure vessels, but in particular welding 6061 alloy is very bad news.

I seriously doubt that he was able to weld from the inside and I am guessing that even the outside weld was very superficial and the heat affected zone was very minimal.


The plug in this cylinders has been know to leak, but I have never heard of one having a catastrophic failure. According to the Mil spec, they were seal welded at the factory, but I am sure in a very controlled condition. There was heat treatment involved with this cylinders.

I have a copy of the MIL specs for this cylinders and you can also download a copy from VDH.

---------- Post added May 5th, 2014 at 10:21 PM ----------

I should mention, the heat treatment in aluminum is affected at a relatively low temperatures.

There was a case in Florida were the owner of two aluminum cylinder had them painted using a process that involved heat. Both cylinders ruptured during the filling process.

Aluminum cylinders that exposed to fire have to condemned.

 

[John C. Ratliff]

John on what premise did you determine they were bad tanks? Not trying to pick on you but from what I read they can be hydro tested vip etc. So I don't see a technical base's vs personal opinion.
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imjustdave, and others wondering,

These were "illegal" cylinders on the civilian market. They were developed under contract for the U.S. Navy, so that the Navy could have anti-magnetic cylinders. There was no ICC (Interstate Commerce Commission) stamp on these cylinders. This means they are not approved for interstate commerce. At that time, there was no testing protocol for cylinders made of aluminum, as all commercially available cylinders were of steel. There is a reason that the person cited above as testing these cylinders did not put his initials as a stamp on the cylinders--he could loose his job/certifiation with DOT if he did. Yes, they may pass the hydro test, but that does not guarantee that they are safe cylinders. The plug has a limited life, and the U.S. Navy had a limited lifetime for these cylinders. They were never built to be hydrostatically tested. Somewhere in my files I have documentation of all this. But can you imagine the liability if a school district allowed an instructor/teacher to have these cylinders for diving, and an accident occurred on these war surplus cylinders (Vietnam War and Cold War)?

As a user of these cylinders in the form of twin 90s, we students learned to hate them, as they were heavy and bulky. Imagine having to do pushups while wearing them--they were instruments of torture for us students at the Underwater Swimmers School. The Navy divers did not like them either, and I know of them being traded for our PJ tanks (twin 42s--steel converted life raft bottles) so the Navy divers would have something light and easily transported via small boat.

SeaRat

PS, I just found my file, and will add scans of the letters I sent out, along with the entry I made for the school district.

John C. Ratliff, CSP, CIH, MSPH*

*I usually do not use my professional designations here, but in this case because it involved an on-the-job matter and was a professional matter, I am including them. CSP stands for Certified Safety Professional, and CIH stands for Certified Industrial Hygienist. MSPH is Master of Science in Public Health, from Tulane University.

 

[captain]

Mine were hydroed five times, the original in 67 then 73, 83 and 85, and I had them done in 09, The first four were done before the DOT adopted the 4 character alphanumeric identifier for hydro testers and just have a symbol between the month and year.

 

[John C. Ratliff]

In early 1979, as a Safety and Health Consultant for the State Accident Insurance Fund, I was asked about these cylinders. I contacted U.S. Divers Company, and interviewed Mr. Grady Ford. He stated that these cylinders had a "tendency to blow up," used "old technology," were "spun cylinders with a plug," had "some instances of failure," and were of a "different alloy" (from my notes). I also contacted the U.S. Navy School for Underwater Swimmers (San Diego, California) and talked to an officer there. He stated that these tanks were associated with "Excessive bacteriology in the tanks," which had to do with a "fungus" and "bad air." They had to be "Rolled every time prior to filling." He also stated that it was "Probably a violation of contract to resell the cylinders." He asked that I "Get purchase order, write them and ask why the Navy got rid of the cylinders." (Again, from my notes from 1979.)

I also called Aquarius Underwater Center in Portland, Oregon (since has gone out of business). They stated that these cylinders "Cannot be hydroed (against the law)," and "Legally cannot be filled." (Again, from my 1979 notes.)

I am presenting the two letters, along with my "Record of Calls" (with names from the school removed). It may be hard to decipher my writing, so here is what I had to say about the calls to this school:

1-30-1979: Sayety Material on Welding hazards. While there, discovered use of ~300 Navy Surplus scuba cylinders; Apparently 4 were being used by students as scuba cylinders. See letter in file. JCR 2 hr.

2-1-1979: Presented letter of recommendations to Both Mr. XXXXX and Mr. XXXXX. Mr. XXXXX responded by promising that all the cylinders will be destroyed as pressure vessels by drilling a hole in the plug. Those cylinders in students hands will be recalled and drilled. I also emphasized to both Mr. XXXX and Mr. XXXX that the students should wear respiratory protection until local exhaust ventilation can be installed. Further, noting the apparent high noise levels in the welding area when students were grinding, I verbally recommended that students wear ear plugs. JCR 1 1/2 hr.

It is still my professional opinion that these cylinders should not be used as pressure vessels. My recommendation for this firm remains the same today, that they should be drilled in the plug, and used only for display.

John C. Ratliff, CSP, CIH, MSPH
"SeaRat"