WIND GIRDERS IN A CONE ROOF

[jor1492]

Hello

Is it necessary a top wind girder and secondary wind girder for a cone roof tank with 7m of diameter and height of 11 m ? Or Are the wind girders only for open roof tanks ?

 

[JStephen]

The top wind girder is only for open top tanks. Stability of the top of the shell is furnished by the roof otherwise.

An intermediate wind girder is used if needed on either type, and omitted if not needed on either type. In a lot of cases, it is more economical to thicken the shell slightly if required than to install an intermediate wind girder.

 

[jor1492]

Thank you JStephen for the good answer.

I have another question. Does the attach ,of the body with the roof, required the use of a Angle beam?, and the function of that Angle beam is only for the attach or does it have another function?

 

[fegenbush]

Yes, a top angle is required per 5.1.5.9.e of API 650 unless the roof is flanged. This is provided for stability of the top shell course during erection.

 

[JStephen]

API doesn't really say what the purpose of the top angle is- keeping the shell round during roof erection is what I supposed.
In the current API-650, you're allowed to omit the top angle if the area furnished in that region matches that obtained with a top angle- see the wording in the top angle specification.

One other thing, I said the roof furnishes stability for the top of the shell- that's assuming a steel roof, an aluminum dome would still use a wind girder.

 

[jor1492]

Thanks fegenbush and JStephen , by answer my questions

 

[lps123]

Hi Can some one advice do you have to consider tank over turning moment due to internal pressure when calculating seismic over turning moment in API650 Annex-E ?