Hello.
How calculate Rnc (radius of the nozzle opening in the vessel along the long chord) for Hillside Nozzle in an ellipsoidal heads (see Figure 4.5.10)?
There are formulas for calculation Rnc in p. 4.5.11.2 for Hillside Nozzle in a head type that is not an ellipsoidal heads.

Thank you very much.

_________________
Best regards.

At first sight I would use the formulas in 4.5.11.2 with the substitution of DR with the value from 4.5.11.1. I agree that this is unclear. Is there anybody with a better solution?

Maybe the coming Addenda will set some light on this issue.

Michael

Perhaps I misunderstand the question or issue. But if the need is to calculate the chord opening in the ellipsoidal head at the nozzle opening this can be found from geometry.

We need to find the "(x,y)" coordinates of the two points at which the ID of the nozzle intersects the head inside surface, then calculate the chord length between these two points.

Point "A" will have an "x" value equal to: DR + Rn ie: (distance from vessel axis to center of nozzle, as measured perpendicular to the axis) + (radius of nozzle)

Point "B" will have an "x" value equal to: DR - Rn

Now determine the "y" values from the mathematical curve of the head.

This latter step can get tricky. The ellipsoidal head has elliptical curve on inside surface in new condition but "parallel" curves are no longer ellipses! By this I mean that the curve on the outside surface of the head (assuming that the head thickness is constant, which it may not be) is not an ellipse, nor is the inside surface when a constant corrosion allowance is applied. Depending upon how precise one wants to be you can take this change in mathematical curve into account.

Once the (x,y) values for both points are found, the length of the chord connecting them is easily found.

Dear Sirs.

Thank you very much for your replies.

Maybe it will be easier to measure this chord opening in the ellipsoidal head after building of head 's model with hillside nozzle in the corroded condition with the help of any graphics simulation software ?

Grig.

_________________
Best regards.

That method would work too.

For myself, I like to calculate when I can, then "scale" when this is not practical.

(that's what we used to call it back in the days of paper drafting, I haven't used that word "scale" for years)

I wish you a nice day.

Hi!

This is an interesting query, posed with a similar situation i would probably resort to using a CAD package e.g. AutoCAD and using the query command ask the software to compute the distance. If you have access to such a package then i would highly recommend using the same.

Hopefully the addenda should clarify this further.

M