Re: [PSUBS-MAILIST] External frames

["D. Blake" <dblake@bright.net>]

Hello Karl:

Stiffening rings can be placed on the inside or on the outside of the vessel.  The only difference according to ASME Code (UG 30) is in the attachment of the rings to the shell in terms of an intermittent weld. For outside rings, the weld should not be no less than 1/2 the outside circumference on 6" centers.  For inside rings, the weld should be not less than 1/3 the circumference on 6" centers.

The fillet weld size shall be the smallest of the following: 1/4", the thickness of the vessel wall, or the thickness of the stiffener at the joint  In terms of material for rings, the preference is toward using rings flame-cut from plate as opposed to rolled material because of possible gaps between the ring and shell from out-of-round rolled rings.  Of course here they are probably referring to vessels with a big O.D. as they refer to 1-2" possible gaps.  No such problem with our pityful small vessels(Carsten excluded).

TTYL,

Big Dave 

-----Original Message-----
From: Karl Fuller <fullerk@voyager.co.nz>
To: personal_submersibles@psubs.org <personal_submersibles@psubs.org>
Date: Friday, August 04, 2000 11:20 PM
Subject: [PSUBS-MAILIST] External frames

Hi Guys,

In contemplating the practicality of a design concept I am thinking of, I need to know or be pointed in the right direction, concerning the pro's & con's of external frames versus internal.

No doubt, there are some structural advantages for internal frames, hull welds are under compression versus tension, and the external frames may need to be heavier for external application. Maybe even a combination could work. External frames and internal bulkheads, for example.

My intention is to create maximum internal space for minimum volume and a double skin to create ballast pockets, bottle storage and above all else, a streamlined hull, from a simple cylindrical pressure hull. The outer skin, would be glass fiber.

 

I'd also like to congratulate Carsten and Dale on their progress. It is very encouraging to read about and view the progress.

Thanks also for all the great scrubber info Paul and the rest.

 

Regards, Karl.