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

[Rick Patton via Personal_Submersibles]

Doesn't look like my posts are coming through. Anybody seeing them?
Rick

On Thu, Sep 7, 2017 at 9:32 AM Steve McQueen via Personal_Submersibles <
personal_submersibles at psubs.org> wrote:

> 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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