Eccentric Sections 1

[DCBII]

I'm looking at a cylindrical vessel, subject to vacuum pressure. The head at one end is a standard ASME 2:1 ellipsoidal head. The cylindrical shell is 20 feet in diameter. The client would like to add a smaller diameter (10 feet) cylindrical section extending off of the head. The client wants this new section's centerline to be offset (eccentric) from the original section's centerline (see the following link: Vessel Sketch). Is this permitted by the ASME Boiler and Pressure Vessel Code (Section VIII, Div. 1)? Are there provisions that cover this situation? I imagine if it is, a finite element model would be necessary. I imagine the joint between the head and the new section will require special attention as well. Any guidance on this?

 

[nickelkid]

You can do it in div 1. If you are getting into the knuckle area - one may desire FEA, but enough information has not been provided...

 

[XL83NL]

Stay out of the knuckles itd say, regardless. I dont think FEA is required, this may very well be covered by standard VIII-1 rules.

 

[SnTMan]

DCBII, under Sec VII, Div. 1 this is permitted, and covered by design rules, no FEA needed. See UG-37, paying attention to limits of reinforcement.

It was recently discussed that the limits of reinforcement may extend onto the cylinder. Life would be simpler if the knuckle were avoided, though.

Might also consider a conical reducer rather than a head, see UG-36.

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[DCBII]

Very helpful SnTMan. I think that was exactly what I was looking for.

 

[richard15]

DCBII,

You can design the cylindrical section as an offset nozzle attached to the existing head. Then create anther file for the cylindrical section plus the small head with design pressure adjusted for the liquid level.

Richard