Re: [PSUBS-MAILIST] Hull Calcs

[Jon Wallace <jonw@psubs.org>]

Brian,

Hull openings and reinforcement is currently up for discussion on the 
members list.  I've sent out an RFC and also sent a pointer to some 
calculators for review before making them public.  Check your mail from 
"member-forum" to review that discussion.

In terms of diameter of the opening you have to first know what is 
considered a "large" opening.  ABS and ASME both say that for a hull up 
to 60 inch diameter a large opening is anything greater than 1/2 the 
shell diameter but not over 20 inches, and for hulls greater than 60 
inch diameter a large opening is anything greater than 1/3 the diameter 
but not over 40 inches.  By these standards, both the K250 and K350 subs 
have large openings.  There is no specific size limit for large openings 
however additional calculations may be required for vessels exceeding 60 
in diameter or openings exceeding 40 in diameter.  ABS requires that 
such designs be submitted for specific approval, whereas ASME provides 
additional information in BPVC Section 8, Mandatory Appendices 1-7.

The above paragraph can be reduced to the following; IF the opening is a 
large opening as defined in the standard, AND the hull is less than 60 
in diameter, AND the opening is less than 40 inch diameter; the 
requirement is that ALL reinforcement be integral to the CT or the 
hull.  Interestingly, integral reinforcement is a requirement anyway for 
externally pressurized vessels since no reinforcement pads are allowed 
on externally pressurized vessels.

ABS 4-4-1A1/7.1.1
ASME BPVC Section 8, UG-36(b)(1) and UG-36(b)(2).
ASME BPVC Mandatory Appendices 1-7.

Jon



On 10/10/2010 2:22 AM, Brian Cox wrote:
> Hey Jon,
>             Are there any guidlines addressing the steel thickness where the
> conning tower intersects the main hull section.  My hull is approx 30" in
> diameter and I'm planning on intersecting it with a 26" section using 3/4"
> thick steel( A516 70g).  That 26" is very close to the 30" diameter of the
> hull itself.  I'm so close to the 30" diameter I'm wondering if I could go
> all the way to the maximum diameter of 30".  Any help on this?
>
> Thanks,  Brian
>
>
>
>
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