Lets say I have a project with the following characteristics:
1 - 5 equal lined tanks with diameters of 16.3 meters and 26.4 meters in height.
2 - Type of roof = Dome Self-Supported Radius = 0,8 D
3 - Roof Thickness = 3/8 9,5 mm
4 - The tanks are connected at the top by a platform structure.
5 - All the tanks with internal floating roofs
6 - The tanks were designed with 0,8D dome roof with 3/8 thickness to adequately withstand the self-weigth and weights of the platform structure / internal floating roof.
a Is frangible joint roof mandatory?
b Is it possible to design a frangible roof considering the project above?
c One way to obtain a frangible joint is when the roof plates are welded to the compression ring with a 3mm seal weld only, and when the roof plates are not fixed to any roof supporting structure. Considering the project above, the roof thickness is 9,5 mm and AWS recommends a minimum weld size of 3/16 4,8mm and also there is the platform structure which stiffens the roof. Then we conclude that considering a 3mm weld wont be effective, right?