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ASME Flange Calculations

ASME Flange Calculations

ASME Flange Calculations

(OP)
I have a flange that has 4 presuure taps drilled from the OD of the flange through to the ID.  Does anyone know a reference showing how to verify this arrangement and its application in a ASME Section VIII Div1 pressure vessel design? I am more concerned how to account for the loss of material in the flange calculation.  This is no longer a standard Appendix 2 flange calculation.  

RE: ASME Flange Calculations

If they're small & central they should have minimal effect.

 In effect, the flange analysis is like the "Ring Rolling" case in Roark, S = MR/Z, where Z is the section modulus of the cross-sectional area.  

You could ratio the Zplain to Zw/hole & account for the increased stress that way.

RE: ASME Flange Calculations

(OP)
Thank you Arto,

The hole sizes are significant.  The flange is a 2"-300lb with (4) 0.6" holes drilled tangent to the inside bore. I will look at the Roark Case but I think because the holes are not radial from the center this case may not apply.

RE: ASME Flange Calculations

I concur with arto's position.
The worst condition would be with radial holes.
Even if the holes had a diameter equal to half the flange thickness, the stress increase as suggested by arto would be only some 15% (assuming of course the holes are at mid thickness).

prex

http://www.xcalcs.com
Online tools for structural design

See http://www.xcalcs.com/docs/symbolinfo.htm if you want to use symbols on these fora

RE: ASME Flange Calculations

Just one comment

A 2" 300# orifice flange to ASME B16.36 have thickness 22.4mm which is the same as a normal ASME B16.5 flange.

This also indicates that you don't have a problem.

regards
Mogens

RE: ASME Flange Calculations

As a matter of curiosity what is the temperature and pressure of your system?

We used similar systems except that we used a Dutchmen in lieu of drilling the flange.  If my memory serves me right we used a 2" thick Dutchmen with 6" Sch 40 304L SS pipe with a 300 class flanges with (6) .75" dia. tangential nozzles in the Dutchman.
One caveat is that in one of the systems I found differential thermal fatigue in the flange and pipe downstream of the Dutchmen after only three months operation.  The temperature difference between the streams varied between 75°F and 100°F.

RE: ASME Flange Calculations

1-You have to tell what you are doing with the flanged connection.
2-so you are using a 2in std flange but you re-bore the bolt connections closer to the id?
please specify.
ER

RE: ASME Flange Calculations

Just to avoid confusion about my reply above.

This was in response to Roca but his posting has since been removed (and I was instructed by the administrator not to include e-mail adress in replies).

Regards
Mogens

RE: ASME Flange Calculations

Mogens
Thanks
I have replied to your address
Regards
Roca

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