UG-39 4

[heaterguy]

We fall into UG-39(b)(2) as far as spacing and hole size, but since we fill the holes with heater rods and weld the rods to the flat head, is it really an opening?

 

[prex]

heaterguy,
your first formula appears to me as the correct one, don't understand the second one that BTW reduces to 4/3*t (?)

prex

http://www.xcalcs.com

Online tools for structural design

 

[heaterguy]

prex,

Is the first one in Section VIII? What makes it correct?

The second one reduces to 1/3*t (I didn't realize that, thank you). It takes the volume of the hole and moves it above the hole in a cylindrical shape with a 2*dh outder diameter and a dh inner diameter.

 

[GenB]

I correct: Miller analysis,
genb

 

[prex]

heaterguy,
reinforcement calculations are based upon reconstitution of metal cut by the opening in all sections through vessel wall made with planes containing the opening centerline. This procedure conceptually works only with areas, not volumes (of course because stresses act on surfaces), so your second formula has no meaning.
The first one is the application of UG-39 rules, as:
-make a section with a plane containing the centerlines of both openings
-area available between the two openings is t_r(p-d_h) (with your symbols)
-only 50% of it may be used for each opening
-the same 50% area is accounted for each opening on the other side
-the available area for each opening is again t_r(p-d_h)
This is the rule. Of course, as discussed above, this procedure doesn't account for the orientation and position of the holes: two holes aligned along a radius are very different from the same two along a circumference, as the first case deals with tangential stresses, the second one with radial stresses, and the two are quite different.
However that's it, at least for the moment...


prex

http://www.xcalcs.com

Online tools for structural design