Restriction Orifice Thickness Calculation/Formula and source Standard

[Turik]

Hi, I want to know the formula to calculate Restriction Orifice Thickness, I found on the internet this one "Minimum RO thickness ≥ SQRT [(0,681-0,651*Beta)*deltaP/Y] * pipeID" it says it is according to R.W. Miller, but I could not find it in the Flow Measurement Handbook Miller 3rd Edition.
Can anybody help me with this matter? Which is the formula and the source (book and chapter or a Standard)?
Thanks.

 

[MJCronin]

Wrong Miller..... (a very common name, BTW)

This Miller refers to the calculation methodologies of Roark as contained in his timeless "Formulas for Stress and Strain"

http://rwmillerengr.com/fcfiles/FAQ.htm

(Miller, of course is selling his own software)

http://www.madinstro.net/tech/opthick.html

Many of the postings on the net refer to something called "ASME 3-31-3 Calculation orifice thickness"

This specific topic has been discussed before on these hallowed fora:





MJCronin
Sr. Process Engineer

 

[Turik]

Thank you very much, MJCronin. I have no access to that ASME 3-31-3. And the link you put with those formulae does not have a source either.

I hope I can find or somebody answers this issue clearly.

 

[ione]

Turik,

You've already received a quite straightforward answer from MJCronin, which seems anyway to elude you.

From plates theory: σmax = 6Mmax/t^2

where:
σmax =max stress
Mmax = max bending moment
t = plate thickness

Moreover σmax ≤ Y
where:
Y = yield strength of the material the plate is made off

From "Roark’s Formulas for Stress and Strain" sec. 11-14 you can find the formula to compute Mmax
Then work out for t (definitely boring) and the game is done.