[PSUBS-MAILIST] Hull Transitions

[Marc de Piolenc]

Many ASME publications, including the Boiler and Pressure Vessel Code, 
are available on the BitTorrent network. Get a BitTorrent client like 
uTorrent and install it, then start searching. A good place to find 
technical material is btdigg.org.

Marc de Piolenc

On 1/5/2014 2:28 PM, Joe Perkel wrote:
> Alec,
>
> It appears that the ASME texts are not so readily available for perusal
> and come at significant cost. I think then that's its fair to say that
> it is simply not important enough for me to consider further and just
> stick with the template I have on hand, which is the K-350's end capped
> cylinder, simple enough I should think.
>
> Thanks for the well described analysis, that alone is quite helpful.
>
> Joe
>
> Sent from Yahoo Mail for iPad <http://overview.mail.yahoo.com?.src=iOS>
>
>
> ------------------------------------------------------------------------
> *From: * Alec Smyth <alecsmyth at gmail.com>;
> *To: * Personal Submersibles General Discussion
> <personal_submersibles at psubs.org>;
> *Subject: * Re: [PSUBS-MAILIST] Hull Transitions
> *Sent: * Sun, Jan 5, 2014 3:05:48 AM
>
> A transition from cylinder to cone is a major stress point, particularly
> if we're speaking of the transition at the larger end of the cone. If
> you visualize which way the plate on each side of the discontinuity will
> flex under pressure, you will see they are rotating in opposite
> directions around the point they are joined, and this means they will
> try to "split open" the weld by increasing the angle at which they
> intersect. I'm aware of three approaches to address the problem:
>
> 1 - Weld it as if it were a normal cylinder to endcap transition. This
> of course will work, but the difficulty is determining up to what
> pressure it will work. The standard math (e.g. ABS spreadsheet) will not
> take the discontinuity into account. Stiffening the cone as if it were a
> cylinder can limit the flexing of the cone, and I've seen diagrams of
> stiffeners placed directly on the discontinuity. See for instance Figure
> 1 on the ABS spreadsheet.
>
> 2 - Use a curved transition piece, similar to the knuckle of a regular
> endcap.
>
> 3 - Use a forged ring for the transition piece. This puts a whole lot
> more material at the discontinuity, since we're now talking a roughly
> triangular section rather than plate.
>
> Obviously #2 and #3 are MUCH more expensive than #1 but will also get
> you much deeper. I don't have any easy math to tell you how much, you
> would want to do FEA on it for sure, whichever of the three approaches
> you took.
>
>
> Best,
>
> Alec
>
>
> On Sat, Jan 4, 2014 at 8:34 PM, Joe Perkel <josephperkel at yahoo.com
> <javascript:return>> wrote:
>
>     Busby is unclear as to how a transition from cylinder to cone is
>     accomplished (fabricated). Ala PC 14 for example. Is the weld joint
>     reinforced or is it simply an abrupt change in angle?
>
>     The issue is relevant in an attempt to reduce volume within the
>     pressure hull where only machinery/equipment is intended to reside.
>
>     Is there a text or diagram somewhere that covers such transitions?
>
>     Thanks
>
>     Joe
>
>     Sent from Yahoo Mail for iPad <http://overview.mail.yahoo.com?.src=iOS>
>
>
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