Hello, today I'm working on the design of a jacketed vessel.

The design of the manhole nozzle is making me think that there's something unclear in ASME App.9.

I'm attaching a pdf representing the detail that I'm speaking of.

I have modeled the vessel shell in a .pvi file, added the manhole nozzle and checked it both with internal pressure (6bar) and jacket/external pressure (4bar).
The resulting design requires a reinforcing pad, and this makes sense to me.
But then I tried to check the jacket with a second .pvi file, and I wanted to check the nozzle opening in the jacket too (because App.9-6(a) says that opening through jacket must meet the usual nozzle design).
A repad would be necessary too... but then APP.9-6(b) clearly states that no repad is required for the jacket side, because the nozzle neck itself is acting as a restraint for the jacket.
This is confusing to me, because it looks like that APP.9-6(a) and APP.9-6(b) are in contradiction.

So, I have a couple of questions about this situation:
1) I think that APP.9-6(b) governs because it refers only to Fig.9-6 details... is my interpretation correct? NO repad is required on the jacket?
2) if yes... how would you work out the pvelite design report, in order to show that APP.9-6(b) has been considered, demonstrating that the holes on the jacket have not been forgotten by the designer ... (it would be nice to have this kind of check implemented into the new "jacket module").

By the way, isn't it weird that the jacket chamber shows a reinforcing pad on a 16mm head and NO reinforcing pad on the 10 mm jacket?
To me, this doesn't make much sense.

I'm looking forward to read your opinion!

Federico

Hi Frederico

Appendix 9-2 states that nozzle reinforcement should be analysed in accordance with UG-37(d)(2). UG-37(d)(2) is not very helpful (in my opinion). This makes reference to UG-37(c) which means you have to reinforce the nozzle of the inner shell for it internal pressure.

Appendix 9-6(a) also refers to UG-36 through UG-45. However, Appendix 9-6(b) relieves you of putting a re-pad on the jacket. That is not the problem. The problem is the necessity of a re-pad on the inner shell. The order of assembly of the jacket to the shell is the real problem. All welding of the nozzle to the inner shell has to be performed from the inside (as I see it). That can present a challenge, because the nozzle to both the shell and the nozzle must be accomplished.

The problem is interesting.