Nomenclature Help

[CW3]

I'm wanting to double check on an item or two pertaining to nozzle external forces & moments in cylindrical vessels......the term Rm = mean radius of shell (inches). Am I to take this as the O.D. on a straight cylidrical vessel?? I'd also like to include in a spreadsheet, calculated values for alpha, sigma, and delta, as shown in the Pressure Vessel Handbook.....any help, ideas, direction...?


Thanks

CW3

 

[JStephen]

I would take "mean radius" to be the radius at the centerline of the plate.

 

[CW3]

That's what I thought, however, I was looking at some reports and compared values against the drawing. It appeared that the OD was used.....hmmmmm. I also understand the relationship between "mean radius" and vessel heads, but the shell issue is still a bit unclear.

 

[jte]

CW3-

I think what you're running into is the recognition that in most cases... it really doesn't matter whether you punch in the inside, mean, or outside radius. Your results won't vary enough to be significant. Yes, there will be exceptions for unusually small diameter and unusually thick vessels. To a certain extent its a case of engineering judgement. Using the OD should be conservative, and easier to figure out than the mean radius.

jt