UG-37 & A2

[loc23]

When performing nozzle reinforcement calculations per UG-37, why does the formula for A2 change from 5*(tn-trn)*fr2*t or tn to 2*(tn-trn)*fr2*L (length nozzle projects outside vessel). I am using Compress and cannot find this in the Code book.

 

[jte]

loc23-

I don't run Compress, but I imagine you input the length the nozzle projects outside the vessel as L. From the formulas you are quoting, you are not using a repad. I would guess that the formula changes when L < 2.5*t or L < 2.5*tn. Otherwise you would be taking credit for nozzle length which doesn't exist. Run some examples and let us know. Maybe use t=1" and tn=.5" and run one case with L=2" and one case with L=3".

jt

 

[prex]

If L=the smaller of 2.5t or 2.5t[sub]n[/sub], as required by code, the two formulae are equivalent.
If L is larger, then the second formula gives an incorrect result. If on the contrary L is smaller, then the second formula is better then the first one (though this is what the code gives!), as it accounts for very short projections.

prex

http://www.xcalcs.com

Online tools for structural design