Cone calculations as per ASME sec VIII Div 1 UG-33 & Mand Apd 1

[GD_P]

Hello forum,

I have doubt in cone calculations as per ASME sec VIII Div 1.
1) In 1-5 calculations, t & tr refers to minimum required thk of cylinder & cone respectively. I am confused whether they correspond to internal pressure OR max thk calculated for internal & external pressure (whichever governs the design). As this clause is related to internal pressure, I think t & tr should correspond to internal pressure only, am I right?
2) For external pressure calculation as per UG-33(f) when the cone-to cylinder junction is not a line-of-support, the required thickness of a conical head shall not be less than the required thickness of the adjacent cylindrical shell. Again I am confused whether ‘required thickness of the adjacent cylindrical shell’ indicated above is for ‘external pressure’ or ‘max thk calculated for internal & external pressure (whichever governs the design)’. IMO, it should be for external pressure, am I right?
3) Same confusion for tr in 1-8 calculations. But ‘t’ term clearly specifies caln as per UG-28. So IMO tr should correspond to ‘max of internal or external (whichever governs the design)’, am I right?
OR
another approach is to use the conservative values for all 1 to 3 i.e., max for internal & external (whichever governs the design). But at the same time I don’t understand, why code has kept this ambiguity (personal opinion, may be due lack of expertise)? This issue could have been solved by putting a few words ‘Internal’ or ‘External’ or ‘Max of internal & external (whichever governs the design)’.
It will be very helpful if you could provide some guidance on this.
Also accept my apology if the doubt is very basic.
Regards,


GD_P

 

[r6155]

Read again (slowly) the title and try to understand

1-5 RULES FOR CONICAL REDUCER
SECTIONS AND CONICAL HEADS UNDER
INTERNAL PRESSURE

(b) Nomenclature
P = internal design pressure (see UG-21)

Similar to the others questions

Regards

 

[SnTMan]

GD_P, r6155 gives good advice. Thorough reading is key to understanding. Study the examples manual or software output if available.

In general, quantities for internal pressure are dealt with in 1-5, external pressure in 1-8.

The design of a reducer section for both internal and external pressure is a very complicated enterprise.

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand