Shell/Cone/Skirt Joint - ASME VIII-1

[marty007]

Hello,

I'm looking into the design of a pressure vessel with a conical bottom head that is supported by a skirt (vessel is not high pressure (<100psi))

The vessel diameter is ~13ft, and the client spec is calling for the skirt diameter to be equal to the main shell diameter, joined at the cone/shell junction. In their specs they are calling for a toriconical head, which I would be happy with, but I'm looking at other options as the sourcing of the toriconical head is proving difficult (cost/delivery/etc...).

In particular I'm looking at ways to build the vessel with a regular cone. I've attached a picture with some diagrams to illustrate the question.

Per Concept 1 in attached picture, if we were to butt weld the cone to the shell, we'd be stuck with having overlapping welds when we join the skirt. Personally I'm not a fan of overlapping welds if it can be avoided.

My main question here revolves around Concept 2. In this arrangement the skirt would be lengthened such that it also acts as the first shell course. Is this weld arrangement the same thing as Fig UW-13.1 sketch f-2 which is not allowed? Sketch f-2 does not appear to indicate the existence of an extended skirt/shell, is this different enough?

I am aware that by not using a toriconical head, I would likely require a stiffening ring in the area of the joint.

Cheers,

 

[pennpiper]

The "Original Design" is the best way to go.

prognosis: Lead or Lag

 

[marty007]

Yup, that's how I want to do it. I'm just trying to find alternatives if for whatever reason procurement has troubles finding the toriconical head.

 

[prex]

Concept 2 is just like det. f-2, so you can't use it. Concept 1 is possible (though not the best): if you don't need the full thickness for the skirt weld, you could use a smaller weld.

prex
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[gr2vessels]

If using conical bottom and tripple joint of shell, bottom and skirt, the reinforcement requirements will make the whole design not feasible. I strongly advise to concentrate over the sourcing of tori-conical bottom.
Cheers,
gr2vessels

 

[marty007]

Thanks everyone for your advice/input.

We managed to find a supplier that is able to supply just a knuckle, and we will form the cone in-house.

Cheers,
marty007