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Re: [PSUBS-MAILIST] Bill Gifford's Project

To: personal_submersibles@psubs.org
Subject: Re: [PSUBS-MAILIST] Bill Gifford's Project
From: Coalbunny <coalbunny@vcn.com>
Date: Thu, 22 May 2003 23:44:24 -0600
References: <20030521144102.44195.qmail@web41804.mail.yahoo.com> <000301c32088$8a73ecc0$c101bf3f@oemcomputer> <003c01c31fec$e32cc1d0$028ca844@FAMILYROOM> <000201c321a8$1efb16a0$81f1b141@oemcomputer>

Speaking of propane tanks....

what is the estimated crush depth of a propane tank and is there a
formula to find that?
Carl


Steven Mills wrote:
> 
> >From: Dan H. <JMachine@adelphia.net>
> >
> > I visited Bill's site and read what you quoted.  Bill's project sure looks
> > interesting but I wish, for confusion sake, Bill would have noted that his
> > propane tanks that were tested to 325 PSI and rated at 250 PSI for INTERNAL
> > pressure!  External pressure is a TOTALLY different matter.   I'm sure Bill
> > realizes this and is designing accordingly.
> >
> 
> Thanks.  That thought had occurred to me just before receiving your
> response.
> 
> Perhaps I need a little clarification on the definition of dual pressure
> hulls.  Is Bill's design a dual hull or a reinforced single pressure hull
> [ using the small tube and frames for reinforcement ; and the smaller
> tank left open ended after the cut or capped-off]? The ends of the
> smaller tank were cut and welded to the larger for hard ballasts.
> For simplicity, my mind envisions something akin to a thermos bottle;
> 2 closed vessels reinforced with frames or stiffening rings between
> the 2 hulls. [ Which brings me to the next question...]
> 
> > One thing to consider when designing one tank nested inside another is that
> > you can't weld your framing to both tanks unless the difference in size is
> > great.
> 
> So, I would think that the framing would be welded on the outside of the
> inner hull?  The outer hull would not only be subjected to pressures
> initially, but also to temperature differentials?  The contraction and
> expansion over time would fatigue and stress the welds at the inner
> part of the outer hull first if the 2 hulls were welded together at the frames?
> The temperature in the inner hull would be affected by intenal environment
> ie., body heat and residual mechanical/electrical heat?  Or are these
> minute considerations?
> 
> >Even if you design it strong enough without the frames welded to
> > both tanks, you still have the risk of corrosion in places that you can't
> > access for inspection.
> >
> 
> Would a foam, dessicant, or bonded covering [ anodizing the steel?]
> solve this problem?
> 
> --Steve
> 
> > Dan H.
> >
> > ---- Original Message -----
> > From: "Steven Mills" <barycenter@earthlink.net>
> > To: <personal_submersibles@psubs.org>
> > Sent: Thursday, May 22, 2003 1:34 PM
> > Subject: Re: [PSUBS-MAILIST] Bill Gifford's Project
> >
> >
> > > >From: Warren Greenway <opensourcesub@yahoo.com>
> > > >
> > > > They are rolled and welded (so, yes, they do have a
> > > > seam.) The ends are then welded onto the tube. This
> > > > is standard practice, and while there may be variation
> > > > you can bank on them being built this way.
> > > >
> > > > Warren.
> > >
> > > Thanks.
> > >
> > > Bill uses 2 tanks with the same ASME rating, but it is a single
> > > pressure hull. [ see quote/specs below ]
> > >
> > > If a double hull were to be designed, would you have the inner hull
> > > at a stronger and thicker spec than the outer hull? [ using 2 propane
> > > tanks ]
> > >
> > > Also, this might seem an oddball question or inconsequential, but
> > > should the weld seams on both hulls be parallel and lined up with
> > > each other?
> > >
> > > --Steve
> > >
> > > ....quoted fromBill Gifford's website....
> > > http://www.giffordmarineinc.com/sub/little_gato5_9_01.htm
> > >
> > > "I have chosen to use two new propane tanks to form the pressure hull.
> > > Each tank is made of A-516 grade 70-pressure vessel steel, .270 inch's
> > > thick. Both tanks were pressure tested to 325 pounds. They have a working
> > > pressure of 250 pounds and are ASME rated with a spec. Plate on each
> > > tank. I am installing three by one half-inch reinforcement rings every
> > two-foot
> > > on center. Plus additional deck and bulkhead framing. The one-tank easures
> > > 17.6 ft. long and the other is 9 ft. I have cut a hole in the top of the
> > larger tank,
> > > around that I intend to install the conning tower, which is made up of
> > parts
> > > of the smaller tank and additional plate. I have cut the ends from the
> > smaller
> > > tank and have connected them on each end of the larger tank for hard
> > > ballast. I have purchased a eighteen-foot by two foot by quarter inch pipe
> > > for the soft ballast tanks. The pipe was split log ways and will be
> > attached
> > > to each side, to form the side tanks. The sub will have a displacement of
> > > approx. 18,000 lbs. "
> > >
> > > >
> > > > --- Steven Mills <barycenter@earthlink.net> wrote:
> > > > > I haven't examined a propane tank closely, but are
> > > > > they filament
> > > > > wound and rolled or are the ends welded to the tube?
> > > > > Is the tube
> > > > > seamless or also rolled and welded? Are they all
> > > > > manufactured
> > > > > the same way?
> > > > >
> > > > >
> > > > > --Steve
> > > > >
> > > > >
> > > > > ----- Original Message -----
> > > > > From: Coalbunny <coalbunny@vcn.com>
> > > > >
> > > > >
> > > > > > Yes, it is!  What about the innerds?  Can we get a
> > > > > spec sheet and
> > > > > > drawings if we want to make something similar?
> > > > > > Carl
> > > > > >
> > > > > >
> > > > > > Steven Mills wrote:
> > > > > > >
> > > > > > > Wow, that's quite impressive !
> > > > > > >
> > > > > > > It's a beautiful boat.
> > > > > > >
> > > > > > > --Steve
> > > > > > >
> > > > > > > ----- Original Message -----
> > > > > > > From: Jeremy Crawford <ISMASC@hotmail.com>
> > > > > > > >
> > > > > > >
> > > > > > > > If anyone hasn't checked out Bill's Sub lately
> > > > >  you should, the exterior is
> > > > > > > > done and it looks awesome.  Kudos Bill, you
> > > > > have done a fantastic job!
> > > > > > > >
> > > > > > > > Best Regards,
> > > > > > > > Jeremy
> > > > > > > >
> > > > > > > >
> > > > >
> > > > http://www.giffordmarineinc.com/sub/sub_5_16_03/Sub_5_16_03.html
> > > > > >
> > > > > > --
> > > > > > "Indeed, desire is the seed of thought, the prime
> > > > > force that activates
> > > > > > the mechanism of the mind." -- Kama Sutra
> > > > >
> > > > >
> > > >
> > > >
> > > > __________________________________
> > > > Do you Yahoo!?
> > > > The New Yahoo! Search - Faster. Easier. Bingo.
> > > > http://search.yahoo.com
> > >
> > >
> >
> >

-- 
"Indeed, desire is the seed of thought, the prime force that activates
the mechanism of the mind." -- Kama Sutra

References:
- Re: [PSUBS-MAILIST] Bill Gifford's Project
  - From: Warren Greenway <opensourcesub@yahoo.com>
- Re: [PSUBS-MAILIST] Bill Gifford's Project
  - From: "Steven Mills" <barycenter@earthlink.net>
- Re: [PSUBS-MAILIST] Bill Gifford's Project
  - From: "Dan H." <JMachine@adelphia.net>
- Re: [PSUBS-MAILIST] Bill Gifford's Project
  - From: "Steven Mills" <barycenter@earthlink.net>

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