umbrella roof for api-650 tanks

huangyhg

umbrella roof for api-650 tanks
good day ya'll.
i'm specking an api-650 type tank to hold potable water.  i understand what a dome and cone roof would look like, but the spec's description of an umbrella roof is a little vague.  does anybody have a source for what one of these roofs would look like, or how they're constructed. this is for a small tank, 40' diameter, the design will call for a self supporting roof.


it looks just like a dome from the ground but the roof sheets are only rolled in one direction.  it's like if you cut long thin triangles say about 6 feet on one end and 6" on the other end, long enough to reach nearly to the tank center from the edge, then rolled them the long way.  installed with laps on their long edges.
thanks ifr,
i can envision what your talking about it.