Frangible, self-supported Umbrella type dome possible?

[rikiraph2]

Is my assumption correct that it is not possible to meet the frangibility requirements for a self supported umbrella type dome roof?
Can anyone confirm or correct me.

 

[IFRs]

Most likely not, but it's easy enough to run the calcs. Yours could be one of those unique situations that does meet the requirements.

 

[rikiraph2]

Thankyou for the response.

What I mean is it can not meet the 1 in 6 slope requirement

 

[gdubyuh]

I would say it is not possible, given that the minimum slope of a dome or umbrella roof is achieved when the roof radius is set at its maximum allowable...120% of the tank diameter (API-650 5.10.6.1). This gives a slope of about 24.5 degrees with respect to the horizontal. The maximum slope for frangible roofs, 2:12 as noted earlier and from API-650 5.10.2.6, is only about 9.5 degrees.

 

[IFRs]

What he said