Tek-Tips is the largest IT community on the Internet today!
Members share and learn making Tek-Tips Forums the best source of peer-reviewed technical information on the Internet!
-
Congratulations TugboatEng on being selected by the Eng-Tips community for having the most helpful posts in the forums last week. Way to Go!
Big square nozzle on a conical roof 1
- Thread starter orama
- Start date
I think FEA is your only hope. I've pursued this case as well as large cylindrical nozzles not on the tank centerline, and have been unable to come up with anything analytical. WRC107/WRC297 seemed the obvious approach, but tank roofs are outside of the range of D/t that they cover. If you find something, please announce it loud and clear, as it would be very useful.
-
1
- #3
Tankman650
Structural
There is a very conservative way to do this for stress. Determine the cone radius at the location of the nozzle. Use WRC107 sphere calculations based on a sphere with radius 2 times your cone radius. (You can derive this based on rotating the nozzle axis on a cylinder so that the local nozzle axis is 45 degrees from the cylinder axis).
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.
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.
Tankman650
Structural
butelja,
The D/t limitation is for CYLINDERS not SPHERES. By using an analysis of a sphere you can get around this limitation.
The D/t limitation is for CYLINDERS not SPHERES. By using an analysis of a sphere you can get around this limitation.
Tankman650
Structural
butelja,
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The method I described is an unpublished procedure by a major tank manufacturer.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????
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????
Try using nozzle pro from
- Status
Similar threads