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Suspended Conil Base Silo

Suspended Conil Base Silo

Suspended Conil Base Silo

I'm designing a silo for storing oil. Shell height is 11500mm, 3800mm internal diameter, internal pressure 490mBarg.
15 Degree Conical tops and bottoms. Supported on a mild steel skirt.
I've searched most of the codes but finding it really difficult to find the correct calculation for reinforcing the bottom cones.
I have used Annex H from EN 14015 and have worked out the distance between supports to be 150mm. This is adding quiet a lot of reinforcing to the base of this vessel

Does anyone know what the correct code I should be using or the best method to reinforce this vessel base?


RE: Suspended Conil Base Silo

If the bottoms are actually cone shaped and not flat, they would normally not require any kind of stiffeners- just a compression ring at the perimeter.  Try increasing the thickness or increasing the slope.

RE: Suspended Conil Base Silo


Your skirt and stiffeners add considerably to the expense .... perhaps they are not necessary ?

Consider designing your "silo" (tank?) more in custom with a commonly used design standard such as API-650.

API 650 allows both "cone-up" and "cone-down" tank bottoms. The API-650 tank bottoms are not supported by stiffeners, they are supported by the ground.

By the way, "cone-up" bottoms are preferred by the major oil companies for crude oil service (for water collection and removal) The "cone down" configuration tends to concentrate the water and the tank bottom corrosion in one central place.

Which oil are you storing ?  Crude ?

Is this your first tank design ?  

Also suggest that you


RE: Suspended Conil Base Silo

I have considered API 650 but I do need the conical bottom end to be supported by a mild steel structure as this is preferred by the end use (there is an access hatch in the side of the skirt to allow them to examine the vessel base and outlet pipe).
I'm not sure what type of oil (this is used in the production of baby powder)
We have in the past fabricated similar vessels based on experience, but I'd be far more comfortable with some calculations to back up our designs.
Last alternative is to run FEA on the structure..



RE: Suspended Conil Base Silo

Ok....I now have a better picture.

But I still think that your design is "too unique"....

I also still feel that a "tank-type design" with two ellipsodal or F&D heads (how about 4000 mm diameter ?) would be a more efficient and cheaper design. Oil can be extracted through a bottom nozzle with an integral elbow

You can still retain the skirt with the hatch access, if desired.

But if the client insists on an expensive bottom-cone arrangement....then so be it !!!

My opinion only



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