API650: F&D Head min thick calc.

[rrickey]

Hello to all, and Thank you in advance.

I have a design for a 9'dia x 25'OAH 316LSS Decarbonator to be built per API 650/S Code. My question is how do I calculate the min roof thickness (F&D Head)?
The tank is at atmospheric pressure, and and has a max liquid level of 6ft (overflow outlet), and a design Roof Live Load of 25 psf.

Any help or insight would be great, as I am new to the ways of "the Code."
;-)

 

[MJCronin]

rrickey,

Use the method in API-650 to calculate the head thickness. For an F&D head, use the method for thickness calculation of a "domed" roof (a similar shape).

If the head shape is an "ASME F&D" shape (there are different types of F&D heads) you can use the equation in ASME VIII to calculate the thickness. Use 2.5 psig as the design pressure. (Bytheway, an "ASME F&D head" has curvature requirements....it is also sometimes called a "torospherical head&quot

What is your roof loading ? Snow ? Deadload ? Wind ? The API-650 code also contains minimum design loads for tank roofs (about 25 psf....as I recall)

Are you going to try to design, test and fabricate this tank yourself or what ?

This is the kind of question that a fabrication shop would know how to answer. Perhaps you could just "spec out" this small tank and get one priced and delivered ?

Hope that this helps

MJC