WRC 107 - EXTERNAL PRESSURE
WRC 107 - EXTERNAL PRESSURE
(OP)
Hi,
Would appreciate some guidance re WRC 107 if possible !
I am designing lifting lugs and doubler pads to lift a vertical vacuum - insulated pressure vessel, with lugs sited near the top of the cylindrical shell, below juncture with semi-ellipsoidal dished end.
My question is - Can WRC 107 methods for calculating stresses in cylindrical shells at the edges of lugs and doubler pads ,due to External moments, be used in the case of external pressure ? My understanding is that WRC allows for internal pressure only. In my case external pressure of x1 bar applies (atmospheric pressure outside, vacuum inside ).
Any help would be appreciated.
Would appreciate some guidance re WRC 107 if possible !
I am designing lifting lugs and doubler pads to lift a vertical vacuum - insulated pressure vessel, with lugs sited near the top of the cylindrical shell, below juncture with semi-ellipsoidal dished end.
My question is - Can WRC 107 methods for calculating stresses in cylindrical shells at the edges of lugs and doubler pads ,due to External moments, be used in the case of external pressure ? My understanding is that WRC allows for internal pressure only. In my case external pressure of x1 bar applies (atmospheric pressure outside, vacuum inside ).
Any help would be appreciated.





RE: WRC 107 - EXTERNAL PRESSURE
RE: WRC 107 - EXTERNAL PRESSURE
Any suggestions as to how I might determine wether imposed stresses will result in buckling failure ? One further question if I may : Using 107, the required doubler and Lug dimensions I have calculated appear to be quite a lot larger than the dimensions of those I have witnessed on vessels in the field. Could it be that other designers are accounting only for shear in determining stresses incurred on lugs when lifting without consideration of the effects on the vessel shell, or perhaps they could be using an internal stiffener ? Any suggestions ?
RE: WRC 107 - EXTERNAL PRESSURE
Suggestions - try WRC-297 to start. I prefer to use FEA, but that's because that's what I get paid to do.
For buckling, the only way to check for local buckling is to use an FEA approach. I suppose that you could try to limit the stresses to the B values from II-D, Subpart 3, but that may be even more conservative. Does your vessel see a vacuum while it's being lifted? Or am I misunderstanding your situation?
RE: WRC 107 - EXTERNAL PRESSURE
RE: WRC 107 - EXTERNAL PRESSURE
Failing that I do have the option of FEA analysis via a professional contact, although am reluctant as prefer hand calcs.
Thanks again for the advice