UDT Aluminum Tank info

[luis]

Hi JB,

You may want to read my last post.

Thanks

[nikeajax]

Luis, you posted just seconds before I did... But yes, I will read it!

JB

[SeaRat]

Jun 28, 2019 10:27:47 GMT -8 nikeajax said:

Luis, you posted just seconds before I did... But yes, I will read it!

JB

I love those duel posts!

Luis,

Thanks for that explanation. Another question--do ships have the resources to do hydrostatic testing on-board? My thought process was that they used a test pressure rating so that these tests could be done on-board ships, without the use of hydrostatic processes. But I'm an ex-USAF guy, with no knowledge of what ships are set up to do. That was also my reasoning on the difference between hydroing these tanks and pressure testing these tanks.

John

[nikeajax]

Uhhh, you sure you need those hydro'ed today sir?

[SeaRat]

I just dug up the original tests of the improved U.S. Divers Company non-magnetic scuba:

Evaluation of the Preproduction Sample of U. S. Divers Co. Revised Two Stage Aqua-Lung Regulator ('Aqua-Master') and Improved Scuba Cylinders
Author: Hanger, GW; Searle, WF, Jr
1959
Abstract: The equipment evaluated consists of U. S. Divers Co's new two stage regulator, the 'Aqua-Master', and a pair of revised type 3000 psi aluminum cylinders, as specified by BUSHIPS, with straight thread O-ring sealing arrangement. The overall apparatus did not meet acceptance criteria; having an unacceptably high exhalation resistance as a consequence of a new design exhaust flapper valve. Substitution of the old style upper cover-exhaust valve assembly brought the resistance characteristics within specifications. The O-ring cylinder seal is basically satisfactory but not in accordance with military standards. Numerous minor mechanical deficiencies are noted for change. (Modified author abstract)

dspace.rubicon-foundation.org/xmlui/bitstream/handle/123456789/3817/NEDU_59_08small.pdf?sequence=4

Note that the Navy EDU wanted an improvement in the Aquamaster exhaust system.

John

[luis]

They don’t do hydro testing aboard ships. That kind of maintenance is done at a depot.
Most ships don’t have much for scuba, maybe a couple of sets for possible underwater inspection at most.

They do have a large number of SCBA for fire fighting. Most combat ships will have at least one large air breathing compressor and either one or two portable diesel driven air breathing compressors for their SCBA. These compressors can be used to fill a Scuba cylinder since they put out Grade E air. They are only required to put out grade D for surface use (fire fighting) but they do put out grade E.

Scuba operations are accomplished from specialized ships. Ships husbandry would normally done from a salvage ship or other specialized ship. Those ships would not do their own hydro testing either. Actually most of their diving operation could be surface supplied.

Seal team deployment can be done from many different ships or submarines. Those guys mostly use re-breathers and again all major maintenance is done at a dive depot (like the one in Panama City).

They have a hydro test machine in Panama City that is used a lot, but I don’t know if they have hydro facilities in most Navy bases. The vast majority of the cylinders that need hydro testing on a regular basis are SCBA cylinders. Those are now fiber wrapped and their operating pressure is 4500 psi. They get tested to 7500 psi. And because they are fiber wrapped, they are retired from service after 15 years (if I recall correctly).

A lot of the hydro testing of cylinders is probably sent out to a contractor now-a-day. Is consider cost effective (but that is highly debatable).

[SeaRat]

I found some of my photos on PhotoBucket of these cylinders, and thought you'd like to see them.


This comes from the March 1970 U.S. Navy Dive Manual.


Here's a top view of the doubles used by the U.S. Navy.


Here's the harness side of these sets.


And here's what they looked like on a dive.

John