Skirt on Cone of vertical vessel 3

[curlyjackme]

I have a cone bottom vessel with a skirt. How is the best way to calculate the stresses in the cone to see if the thickness is sufficient due to the attachment of the skirt. Any help will be appreciated. I have never put a skirt on a conical head. Thanks in advance.

 

[vesselguy]

I'm sure you will put a transition knuckle at the shell to cone joint; hence, by using a knuckle, the analysis would be exactly the same as that for a hemi-head.

 

[curlyjackme]

Sorry should have clarified that point this is a small vessel 96" ID. There is no knuckle in the cone. It is a straight cone section approximately 80" long. Cone is 96"ID to 5.75" ID.

 

[TGS4]

I'm afraid that you're stuck with a design-by-analysis.

 

[vesselguy]

I see. Do you really need a skirt? Find out if that is really needed or it is just because the process engineer put that on the datasheet for the heck of it. Legs or even lugs might be better solution. But, if you really must have a skirt, for cone bottom vessels I have specified that the cone be welded directly to the inside of the bottom shell course with full pen weld, with about 50 to 75mm of the lower shell course protruding beyond the cone to shell joint. This stub is for later full pen butt weld of the shirt to the shell. Also this way, I get access for MT of the weld at the crotch and you can even UT the cone to shell joint from the inside. I'm sure you know that you will need compression ring near the junction. with this solution you don't need to do your fancy analysis. Good luck.

 

[MJCronin]

I agree with vesselguy.....

For this small vessel, legs are usually a better choice.

Do not include a skirt in the design unless there is a very good reason to have one (ie. very tall vessel - high seismic or wind loads)

-MJC