Frangible roof if tank on F.7 1

[inammanj123]

hi,

I am designing 15.5 m cone roof tank with 5.6 kpa internal pressure. Tank is going on F.7, and client is asking for supported roof Below are my queries:

1- IF tank is on F.7, that means tank is uplifting, can roof be made frangible in this case.
2- Can roof be rafter supported type in case it is going on F.7.
3- F.7 means you also have to check roof on API 620, SO in that case can the roof be supported??
4- Are the formulas from F.4 and F.6 applicale if tank is on F.7,because the decision tree of Annex F, does not say so. In my case failure pressure(F.6) comes out to be less the design pressure specified by client, but in F.7 you need meet Failure pressure requiremnt??
5- as per my understanding compression area cannot be less than calculated in F.5, SO if maximum frangible area comes out to be less than area of F.5, the frangibility is not possible.


Regards,
Inam

 

[Hardarie]

1. no, you can't designed frangible roof for API 650 F.7 tank, use safety valve in lieu of frangible joint
2. yes
3. yes it can,
4. no, you must follow F.7 if tank is at F.7
5. thats describe the no. 1

 

[Duwe6]

Try searching for "frangible roof" in the previous posts. Your tank will be too small to have a viable frangible roof.