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

Rick Patton via Personal_Submersibles personal_submersibles at psubs.org
Thu Sep 7 13:45:19 EDT 2017


Thanks Keith

On Thu, Sep 7, 2017 at 10:38 AM k6fee via Personal_Submersibles <
personal_submersibles at psubs.org> wrote:

> Reaching me.
>
> Keith T
>
>
>
> Sent from my Verizon, Samsung Galaxy smartphone
>
> -------- Original message --------
> From: Rick Patton via Personal_Submersibles <
> personal_submersibles at psubs.org>
> Date: 9/7/17 10:08 AM (GMT-08:00)
> To: Personal Submersibles General Discussion <
> personal_submersibles at psubs.org>
> Subject: Re: [PSUBS-MAILIST] K-250 Angle Stiffener Web Question
>
> 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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>> > >
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