More to the point what was the PC-8 Conning tower Penetration thickness
and what was the reinforcing etc of the 8 viewports. ASME / ABS allows for
more holes but the overlapping of reinforcing allowable areas must be
compensated for. It would be great to get a blueprint of how it was built in
that area
Regards, Hugh
From:
owner-personal_submersibles@psubs.org
[mailto:owner-personal_submersibles@psubs.org] On Behalf Of vbra676539@aol.com
Sent: Wednesday, 21 April 2010 1:10 p.m.
To: personal_submersibles@psubs.org
Subject: Re: [PSUBS-MAILIST] Hull Penetration and Reinforcement
It
would be interesting to find out about the conning tower pens. My PC-8 print has
a 28" pen, which allows for 8 X 8" viewports in the circumference.
And I'm here to tell you, that's better than six.
Vance
-----Original Message-----
From: Jon Wallace <jonw@psubs.org>
To: personal_submersibles@psubs.org
Sent: Tue, Apr 20, 2010 8:38 pm
Subject: Re: [PSUBS-MAILIST] Hull Penetration and Reinforcement
Some additional
information.
1) Vessels under external pressure only need 50% of the reinforcement as a
vessel under internal pressure.
2) Reinforcement pads are no longer acceptable under current standards. All
reinforcement must be integral to the hull and/or penetration nozzle.
3) The maximum size hole for a vessel with diameter up to 60 inches, is 20
inches. So what do you do if you want a 24 inch ID conning tower? ABS says to
submit plans for specific approval. ASME says that 2/3 of the reinforcement has
to be within the "limits of reinforcement" which is the lessor of
2.5x hull thickness or 2.5x nozzle thickness. Since manned submersibles must
have ALL reinforcement integral to the hull or nozzle, a 24 inch ID conning
tower already complies with the 2/3 rule assuming you have followed all other
requirements as well.
4) I forgot to provide the link in my previous mail for the white paper
proposing an alternate method of calculating reinforcement. One of the
arguments presented by the author was that the current rules are so
conservative they result in a material thickness that poses a structural threat
to the pressure vessel due to the weight of the finished nozzle alone. I
noticed that this paper was written in 2000 and although I have not seen the
2010 version of ASME BPVC rules, I know that in BPVC 2007 ASME had not adopted
this papers argument. Of course, I'm not sure it was even submitted to ASME for
approval. It's very interesting reading since the authors proposal is based
upon FEA and field tests of prototype vessels that he shows match FEA
results.
http://www.codeware.com/support/papers/bildy.pdf
Jon
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