Gussets in lieu of cone

[rcrowe]

Instead of using a conical transition (going from smaller diameter shell up to a larger diameter shell), can a flat plate be used with external gussets, like a baseplate arrangement turned upside down ?

 

[jte]

rcrowe-

Except for the gussets, your description sounds like one which could be evaluated per VIII-1 UG-39. In fact, except for the nozzle cutout, your description sounds just like Section A-A in Figure UG-39. Depending on your pressure, temperature, and diameters, it may make sense. I don't have much experience with flat heads, but I'd be leery of the dead spot in the inside corner from a corrosion perspective. If you have a benign service, I don't see a reason to not go with that design. Adding gussets might reduce the thickness of the flat head, but you'd be into the world of FEA to get a decent analysis. If the vessel is running hot, I'd stay away from gussets simply from a thermal stress perspective.

jt

 

[bmoorthy]

Provision of Flat plate and a hole in the center and connecting samller pipe, is a common practice when going from large to small dameter. It is not necessary to provide gussets, so long as the thikness is adequate. The calculations are not difficult. If i recollect properly (I do not have ASME readily), there is an Appendix in ASME Sec VIII Div 1 which would give you guideline as to dealing with holes in a flat head.

i have encountered this type of joints in Ejectors, where the pressures are not that high, and the Dia is also not very high but falls under the Scope of ASME Sec VIII Div 1.

If you are in US check with CORRLO Reynolds 9I think these guys manufacture Ejectors). If you are in India, Check with Godrej and L & T.

Also refer to UG 90, UG 93 and UW provisions for corner joints.

 

[GenB]

It al;l depends on pressure, temp and diameter,
if for pressure > 100psi and dia >30 inch you will probably have no choice but conical transition. after that theplate will end up > 2in range. and a lot of welding pwht and so on.
ER