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  • Bolt Spacing Calculation for flanges

    Discussion in 'Calculations' started by mvalenti, Nov 12, 2009.

    1. mvalenti

      mvalenti Well-Known Member

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      I have become rusty when it comes to performing hand calculations. Can someone help me with the steps involved in fastener spacing requirements for a bolted flange?

      Both flange base materials are 5052 al, 0.125 thick.

      Gasket is silicone sponge. 0.125 thick

      Hardware 10-32 bolt.

      -MArk
       
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    3. MechEngineer

      MechEngineer Member

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      Hi Mark. Is there a compression stop for the gasket to prevent overtightening? Perhaps the answer depends on the pressure within the pipe and how stiff the flange material is. Sorry to be a bit useless here but I haven't a clue. :oops: Would be interesting to know the answer. Anyone else?
       
    4. mvalenti

      mvalenti Well-Known Member

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      Its actually a gasket for an access panel, for both water and EMI. Here is my problem (post coffee, earlier post was pre-coffee)....

      I have a gasket, 0.63 x 0.125 thick cross section. The gasket dimensions are 40.5" long x 24.5 wide. According to the deflection curve @ 25% deflection (reccommended) I get a load of about 13lbs per linear inch. So that means a total closing force of 3225lbs.

      My access panel is made from 5052 aluminum 0.125 thick, and the enclosure is of the same material and size.

      I plan on using 10-32 screws to fasten the panel to the enclosure. The catalog reccommends spacing for sheet metal flanges to be 2 inches.. This seems excessive...(Book clearly states this is on the conservative side) I would have close to 30 fasteners!

      I would like the deflection between bolts to be no greater than 5%. Would an evenly distributed load on a simply supported on both ends beam calc be the way to figure this out?

      -Mark
       
    5. mvalenti

      mvalenti Well-Known Member

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      Found it! Nevermind... :D
       
    6. MechEngineer

      MechEngineer Member

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      How did you approach the problem in the end? I would be really interested to know how you calculated it.
       
    7. mvalenti

      mvalenti Well-Known Member

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    8. mvalenti

      mvalenti Well-Known Member

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      Then confirmed with simply supported beam calcs in the end.
       
    9. TTALALAJ

      TTALALAJ New Member

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      I have a similar issue determining bolt spacing. I have a cover that closes off a 47" x 59" area in a vessel under vacuum (4.3"wc). I used the Engineers Edge formula, but struggle with the min/max gasket deflections & min/max gasket pressures. I do not have a deflection curve for the .125" thick EPDM gasket material I plan on using, so I am not sure what to use for these variables. Also, what did you use for the min/max gasket pressure? Any help is appreciated. I need to keep the bolts to a minimum on this. Being under vaccum over such a large area, I dont think I should need much. I have calculated the pressure exerted on the gasket by the vaccum to be 1.12psi.
       

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