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Shell to head thickness

Shell to head thickness

Shell to head thickness

(OP)
Hi,

I have a 24" id cylindrical shell for which we calculate the thickness at 5 inches, according to ASME VIII.

We need to put an end closure on the shell and want to use a hemi head, but the thickness calculates at 2 1/2 inches, which would leave me with a big thickness mismatch at the welded joint.

Is it ok to do this ?
Do I taper the shell to suit ?
Do I match id's and not worry ?
Do I make the hemi head thicker to reduce the mismatch ?

Any help is appreciated.
Regards.

RE: Shell to head thickness

There is a picture in the code of how you should do this.

synopsis...the head is not 24" id...but rather an id based upon matching centerline of metal.  the head is not a full hemispherical but cut back to get a matching point on inside surfaces.  the shell is ""LONGER"" than the tangent to tangent length of shell.  the outside surface of shell is then tapered from the tangent line up to the seam.

you can do all this welding instead of cutting back head, but it is a pain, more expensive and more nde

what this all boils down to is the shell above tangent line is considered part of the head and can be thinner than the cylindrical shell and any reduction of thickness is is done on the head side of the tangent line.

RE: Shell to head thickness

(OP)
Understand, very clear explanantion.
Thank you.

RE: Shell to head thickness

PS. It may be worth considering a Div. 2 design; higher stress, reduced thicknesses.  

RE: Shell to head thickness

dbday

Please contact a Pressure Vessel EXPERT for this case.

My opinion only.

Regards

r6155

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