External pressure on an ellipsoidal head ASME VIII div 1 (UG-33-1b)
External pressure on an ellipsoidal head ASME VIII div 1 (UG-33-1b)
(OP)
I have run into a little problem. I am supposed to calculate a formed head of a semi ellipsoidal shape that is under a external pressure. This is my first time doing this calculation so this might be a really stupid question, but anyway: I have followed the steps and arrived in subpart 3 of ASME II, part D. My head is of A-387 22Cl.2 material, so I should look at Fig. CS-2. But when I look in the diagram I see only graphs for up to 900°F and my design temperature is 560°C (1040°F). Is there a way around this or am I missing something totaly obvious?
Thanks
Pontus
Thanks
Pontus





RE: External pressure on an ellipsoidal head ASME VIII div 1 (UG-33-1b)
If that doesn't work, you have to choose a different material.
RE: External pressure on an ellipsoidal head ASME VIII div 1 (UG-33-1b)
RE: External pressure on an ellipsoidal head ASME VIII div 1 (UG-33-1b)
Is it possible that you could use a lower design temperature for the external pressure case?
-Christine
RE: External pressure on an ellipsoidal head ASME VIII div 1 (UG-33-1b)
TGS4's response is correct. Christine's solution may work for you. Often the external pressure requirement is accompanied by a different design temperature.
Do a search for Code Cases as TGS4 suggested. You may find something useful there.
Another option since your temperature is fairly close to the 900°F limit is to put a relatively thin refractory layer in the head - say 1" (25mm) or so. You'll have to run the calc's to determine the expected metal temperature, but I'd bet that 1" (of even a hard face, relatively high conductivity) refractory would work.
jt