Difference in limit of half apex angle of conical sections in internal & external pressure design

[PVDEngg]

Hello all,

as per VIII.1 Appendix 1-8 Clause (a) texts "The formulas of (b) and (c) below provide for the design of reinforcement, if needed, at the cone-to-cylinder junctions for reducer sections and conical heads where all the elements have a common axis and

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the half-apex angle 'alpha' ≤ 60 deg. Subparagraph (e) below provides for special analysis in the design of cone-to-cylinder intersections with or without reinforcing rings where 'alpha' is greater than 60 deg."

May I have some clarity if, as shown in fig. 1-4, limitation of 'included angle' is 60 deg (i.e. half apex angle <=30 deg.) or half apex angle=60 deg. Throughout the rest of the code book 'alpha' is half apex angle and its limit is @ 30 deg. Appendix 1-5 for internal pressure specifies same limits @ 30 deg. so is it like for external pressure it is 60 deg. or what?

Thanks for guidance in advance.

 

[SnTMan]

PVDEngg, refer to UG-32 (g) and (h) and also to Apx 1-5(g) for cones under internal pressure with alpha > 30 deg.

Regards,

Mike

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

 

[PVDEngg]

Thank you for your reply SnTMan.

Yes, I understand that there are provisions for design of conical sections with half apex angle > 30 deg (i.e. included angle > 60) for internal pressure in clauses you mentioned.
But they guide ultimately to U-2(g) in 1-5(g).

However, whenever it comes to external pressure design for conical sections, somehow this limit of half apex angle increases from 30 deg to 60 deg (UG-33(f)(1), UG-33(f)(2), 1-8(a), 1-8(e)).

And in same manner it guides to U-2(g) for half apex angle > 60 deg (i.e. included angle > 120 deg) for external pressure design reinforcement calculations in 1-8(e).

I am trying to figure out logic behind this liberty in increase of angle from 30 deg in case of internal pressure calculations to 60 deg in case of external pressure calculations of conical sections.

Hope I have put my query with better clarity this time.

Thank you all.

 

[SnTMan]

PVDEngg, that I do not know. Apologies.

Regards,

Mike

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

 

[PVDEngg]

@ SnTMan: Thanks for your response sir.

I shall delve this till some of the esteemed senior members of this forum come across this one and reply.

Thank you all.