Hemi Head attached to Cone

[toomuchespresso]

We have a vessel we are analyzing where there is a hemi head attached to a conical shell section. The head has a larger ID than the small end of the cone it is attached to. This was done so that the head is shorter and is close to tangential to the cone. The head comes in with a tangent angle of 39.5° while the cone is a standard 30° half apex. Any advise on how to analyze this? I was thinking of comparing the differential angle based on the delta measurements in ASME Sec. VIII Div. 1 Appendix 1-5.

 

[racookpe1978]

Submit a sketch (to scale!) of the proposed joint, and please include the actual thicknesses of both the hemi-head and the cone. The description seems contradictory, and the possible weld geometry and weld prep angles don't make sense to me.

 

[SnTMan]

toomuchespresso, also note "delta" is only a function of pressure and cylinder properties. It is not defined by geometry.

Regards,

Mike

 

[gr2vessels]

The vessel description you presented is not in accordance with anything remotely close to a clause of ASME VIII. You have some options, but they require logical engineering, like make the joint line-up, ie. shorten the cone until the tangent reaches 30 deg to match the cone angle. Then you do a decent FE analysis of the joint.
Nevertheless, you still can use the FEA even if there is an angular mismatch between the cone and the bottom head. Most important, there is no provision in the old cookbook ASME VIII for your configuration, other than the indication to use 'other' engineering methods to design your joint.
Cheers,
gr2vessels

 

[toomuchespresso]

Thanks for the feedback. I think we'll just ask the vessel supplier to do an FEA on the joint. I didn't know if this code allowed the configuration (sorry racookpe, no sketch available). The fabricator was treating it as a floating head per Appendix 1-6 and didn't consider the discontinuity.