Big square nozzle on a conical roof
Big square nozzle on a conical roof
(OP)
Does any one know where to find the best approach to calculate the stress and deflection on a big square nozzle placed on a bin conical roof. I don't have FEM software.
Thanks
Thanks





RE: Big square nozzle on a conical roof
RE: Big square nozzle on a conical roof
Remember stresses from WRC107 are 45 degress from your roof principal axis.
Deflections are not handled in WRC107. You can find some information in Roarks formulas for stress and strain that cover radial loads on a sphere.
RE: Big square nozzle on a conical roof
How do you rectify that the D/t ratio for most tank roofs is beyond the end of the curves in WRC107?
RE: Big square nozzle on a conical roof
The D/t limitation is for CYLINDERS not SPHERES. By using an analysis of a sphere you can get around this limitation.
RE: Big square nozzle on a conical roof
OK, but a small portion of a CONICAL roof is CYLINDRICAL, NOT SPHERICAL. Is there published work that states your opinion that substiting SPHERICAL for CYLINDRICAL is valid?
RE: Big square nozzle on a conical roof
Actually a cone is a CONE not a cylinder or sphere!
The method I described is an unpublished procedure by a major tank manufacturer.
I agree that a cone with a small included angle resembles a cylinder. The roof of a tank generally has a shallow slope and is closer to a sphere. I have and am sure you have also, modeled a dome or sphere in FEA as a series of cone segments.
The problem is to determine stresses in a cone using WRC107 when the paper only addresses cylinder and spheres.
The same problem exists with buckling equations. Most tank codes have buckling equations based on formula for a cylinder or sphere. WRC69 developed a method of equating a cone to a cylinder for these buckling equations. Most fabricators use this for buckling and WRC107 analysis. It does not make the method right, just makes it a way to get an answer(conservative I hope) when none exists.
By the way, I have never seen a published method of using a cone as a cylinder for WRC107 analysis. I wonder how far off the results are if compared to FEA????
RE: Big square nozzle on a conical roof