Re: [PSUBS-MAILIST] Pressure Hull Support Ring Types

[Joe Alvarez <joeoutland@yahoo.com>]

Brent; 

 

Carsten has a good idea and makes a valid argument. 

 

Personally I would attempt to seal the metal before on as many non-welded points before starting this process or fill the cavity with a expandable polyurethane.  I would do that out of paranoia about the rust if there was a leak internally on one of the welds that you didn't' test properly.  It will only take one of the welds internally to not seal perfectly and you could introduce fresh air and any moisture from the air. 

 

I would hate to build something and then have it rust out years later on a dive, especially in a place where you can't see or clean out. 

 

I would think that you could use square tube steel and seal that up on the ends to get the same results you are looking for.  I am biased toward tube steel for its ease of working with, cheap price, and general strength and durability.  Of course I believe it will weigh more then what you are looking for but no matter what you do you will have to weld the entire length. 

 

But this is just the ravings of my mind. 

MerlinSub@t-online.de wrote:

Hi Brent, if you weld the H frame on both side of the flank to the hull with a small weld there will be no problem. The oxygen between the two surfaces between the weld will be eaten by a very small amount of rust and than the corrosion stop complete because of the lack of oxygen.

best regards Carsten

"Brent Hartwig" schrieb:
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> Hello All
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> I figured it was time to get my feet wet sorta speak and start posting.  Call me the newbie bulge rat if you want to, but remember I know where the last crew left the rum stash.
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> I've been trying to keep up with what Peter Madison is doing on his new sub UC-3. It looks like he is using a little different ring bracing structure to support the main pressure hull in the UC-3 then he used in Kraka and what we see in the Euronaut. It looks like the Euronaut used rolled I-beams which is a very practical way to get a strong ring quickly with allot less welding. I don't like welding around the corner anyway. I was thinking of doing a design on my sub much like what I see Peter is doing on the UC-3 in a T beam style, but I liked the idea of not having to cut up large panels of steel for those flat vertical sections of the rings then trying to use up the scraps else were.
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> I think the I-beam design is stronger but I was concerned about rust and condensation between the welds holding the I-beam type ring onto the outer hull? As you know if you don't design a sub to be able to reasonably deal with rust in saltwater you'll pay for it later. I'd love to hear Carstens thoughts on this as well as anyone else's.
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> I have noticed that Freya looks to have the same T Beam type support rings as the UC-3. I also noticed that Kraka has Solid bar steel support rings so in that design you would have the small voids I was talking about between the welds holding the rings onto the outer pressure hull. I would be interesting to hear Peter's thoughts on this as well as any one else's. I suspect it's more or less sealed and shouldn't be a problem but it would be good to know real life data. If one were to TIG weld it they would have a better chance of them being totally sealed but it's allot easier if you can MIG weld them.  I'm also interested in this basic ? Of over laping metal in regards to exterior weldments since it's in allot of water most of the time.  I've seen so many subs turn into rust nightmares really fast that I need to design just about everything with that in mind.
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