That is what I would do without FEA. However it depends on how much your ratio is of shell thickness and rib reliance. i.e. Thick shell few ribs it is not so important but thin shell and larger and more ribs equals more care. Hard to comment without seeing what you are trying to do. Hugh From: owner-personal_submersibles@psubs.org [mailto:owner-personal_submersibles@psubs.org] On Behalf Of ojaivalleybeefarm @dslextreme.com Yeah, I figured it was something like that. So if I'm following you, would it be best to weld outside brackets in the areas where you have your interal ribs? On Fri, Feb 17, 2012 at 12:46 PM, Hugh Fulton <hc.fulton@gmail.com> wrote: It is not the welding on of brackets that is the real problem. The bigger problem is that if the component you are welding on is in an area of stress and that component is not stressed or more highly stressed then generally the points of attachment furthest apart are likely to exhibit stress points which may exceed acceptable limits. For example welding on a length of support bracket to the hull. The hull will compress as being part of the pressure vessel but the bracket will not. Hence the welds at the ends of the bracket will be trying to tear off. This sort of thing shows up in FEA. Moral of the story is that short multiple brackets or fixtures are better than long ones. Don’t put brackets on which extend past the internal ribs and onto the shell. Don’t weld onto the knuckle of the heads without an FEA. Vessels are designed to allow stretch, compression and movement under pressure. Restriction of these movements can cause unwanted stresses. Just a cautionary note from BTDT. Hugh From: owner-personal_submersibles@psubs.org [mailto:owner-personal_submersibles@psubs.org] On Behalf Of ojaivalleybeefarm @dslextreme.com Hi Alex, Yes, I guess that's what I'm asking. As far as I know I don't think it would be a problem. If anything I may be adding more strenght to the hull, however there may be issues of unbalanced stresses. I need to add some structure to be able to tie my pressure hull to the ferro-cement hull. I don't want any movement so I was planning on some steel truss like supports. On Thu, Feb 16, 2012 at 10:01 PM, Alex <spm2@nomad.ignorelist.com> wrote: Are you concerned about the mild steel mixing with the stronger pressure hull
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