Pressure vessel heads
Pressure vessel heads
(OP)
What are the advantages of ellip. head against hemispherical head? I guess with hemi head you get more volume and lesser thickness of head. Is it easier to fabricate ellip. heads as against hemi heads? Also with hemi heads you lose more volume in the skirt. Is that an impotant consideration?
Are ellip. heads flatter than 2:1 ratio common? I mean higher D/2h ratio.
Are ellip. heads flatter than 2:1 ratio common? I mean higher D/2h ratio.





RE: Pressure vessel heads
RE: Pressure vessel heads
The inside spherical or crown radius of Ellipsoidal Heads is 0.9D. The inside spherical or crown radius of Hemispherical Heads is 1.0D.
The Ellipsoidal Head has to have a major-to-minor axis ratio of 2:1. The Hemispherical Head has to have a hemispherical shape.
RE: Pressure vessel heads
· The blank diameter of Ellipsoidal Head is smaller as compared to the blank diameter of Hemispherical Head
· Ellipsoidal Head is easy to form.
There is one disadvantage with Ellipsoidal Head. We cannot weld any nozzle on the Knuckle of Ellipsoidal Head. Whereas for Hemispherical Head, there is no knuckle.
RE: Pressure vessel heads
RE: Pressure vessel heads
I do not agree with your statement about nozzles in the knuckle region of F&D or elliptical heads.....at least not for vesels designed under ASME VIII
Whereas it is "bad practice" to locate a nozzle in this region of the head, ASME VIII does not prohibit this.
Review this thread:
http://www.eng-tips.com/viewthread.cfm?qid=67661
You should note that the British Pressure Vessel Standard, BS 5500, puts limits on nozzle locations, but ASME VIII does not.
MJC
RE: Pressure vessel heads
I agree with your point.
However, we should try to avoid welding any nozzle to the knuckle of ellipsoidal/torispherical head.