[PSUBS-MAILIST] K-250 Angle Stiffener Web Question

[Steve McQueen via Personal_Submersibles]

Yes, I have some. I am planning on using them for the light weight stuff.  The holes I was contemplating were to help hold a little more weight than those devices might. I was hoping I was done with  all the welding but maybe not. 

Thanks,
Steve

---- Alec Smyth via Personal_Submersibles <personal_submersibles at psubs.org> wrote: 
> Steve,
> 
> If you go to a hardware store you might find some little aluminum security
> devices for locking sliding doors. I'm sure TrueValue has better (wink wink
> for Scott) but at Home Depot I found some that fit the K250 stiffener
> flanges perfectly. They clamp on with a set screw, and give you a tab you
> can drill for attaching things.
> 
> Best,
> 
> Alec
> 
> On Thu, Sep 7, 2017 at 10:24 AM, Steve McQueen via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
> 
> > Sean, thanks. I was hoping you would respond : )  I did have a clamping
> > approach in mind that I will revisit.
> > Thanks,
> > Steve
> >
> > ---- "Sean T. Stevenson via Personal_Submersibles" <
> > personal_submersibles at psubs.org> wrote:
> > > The minimum moment of inertia of the combined section of the stiffener
> > plus an effective length of the pressure boundary shell may be specified by
> > design, but in any case is to be calculated in consideration of the minimum
> > at the locations where any holes exist. Holes in the flange are far more
> > detrimental than holes in the web, with the mininum impact hole being a
> > hole which is coincident with the neutral axis across the combined section.
> > (i.e. holes drilled in the center of the web of an I-beam have the least
> > impact).
> > >
> > > Better than drilling holes would be to simply clamp to stiffener rings,
> > or weld on brackets or studs such that no material is removed from the
> > stiffener section. Otherwise you do have to account for the reduced moment
> > of inertia of the stiffener section at the hole location in your buckling,
> > inter-stiffener strength and stuffener tripping calculations.
> > >
> > > Sean
> > >
> > >
> > > On September 7, 2017 6:51:03 AM PDT, Steve McQueen via
> > Personal_Submersibles <personal_submersibles at psubs.org> wrote:
> > > >All, as most probably know a K-250 has internal angle stiffeners (L).
> > > >
> > > >In my rebuild I have avoided drilling any holes in the web portion of
> > > >these stiffeners (actually had some existing holes from the original
> > > >build welded up/filled).  However, I am finding it would be nice if I
> > > >could drill a few small (1/4") holes to help mount some interior parts.
> > > >I believe I am looking at 1 to 3 of these holes max. in any single
> > > >stiffener web.
> > > >
> > > >Calculating any reduction in functional strength that might result from
> > > >a few small holes isn't straight forward.  I guess I am looking for
> > > >some feedback from those who understand the web function of an L
> > > >stiffener better than I.
> > > >
> > > >My guess is this wouldn't be a significant issue and I an being too
> > > >anal.
> > > >
> > > >Thanks,
> > > >Steve
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