Hello

I am the dealer for Trinidad and Tobago, I went to demo TANK for a company and we did a comparison of there calculations versus tank, they used an excel sheet base on API codes not sure what version but it was not the latest either 10 or 11. Anyhow most of the calculations match expect for one or two lines. I wondering if you can help me out.. i am sending the two files to you.

Problem 1:
SHELL COURSE ALLOWED FLUID HEIGHTS
Fluid Heights for Three Cases
COURSE DESIGN TEST REQUIRED
(ft. ) (ft. ) (ft. )

1 32.000 46.742 32.000
2 24.237 38.410 24.000
3 24.237 38.410 16.000 why this value for design
4 24.237 38.410 8.0000 why this value for design and what does it mean

Problem 2

WIND GIRDER COMPUTATIONS
Top Girder, required section modulus(in^3): 11.520
Distance from top to intermediate
wind girder (ft): 17.578

they got intermediate wind girder to be 14.42 and modulus to be 3.32 and even when they used a height of 17.578 they did not get a modulus of 6.3281

The section in the api code that it referred to 3.9.7.6 i could not find any information there.

Intermediate girder section modulus (in^3): 6.3281

TRANSFORMED SHELL COMPUTATIONS, Girder #: 1
Trnsfrmd shell height below last girder(ft) 28.839
Individual transformed course & height (ft): 4 8.0000
Individual transformed course & height (ft): 3 8.0000
Individual transformed course & height (ft): 2 8.0000
Individual transformed course & height (ft): 1 4.8393

TRANSFORMED METHOD, GIRDER # 1
Dist. from top/previous to wind girder (ft) 14.420
Req section modulus of this girder (in^3): 5.1911

TRANSFORMED SHELL COMPUTATIONS, Girder #: 2
Trnsfrmd shell height below last girder(ft) 14.420
Individual transformed course & height (ft): 3 1.5804
Individual transformed course & height (ft): 2 8.0000
Individual transformed course & height (ft): 1 4.8393

Can you provide some insights into this. I do not know much mechanical engineering as i am a chemical eng by profession. Explaining these differences were testing!!!.

Regards
Ritchie

The "allowed fluid height" is simply a rearrangement of the required thickness equation. As you get higher in the tank, the minimum thickness is typically over-ridden by the Code minimum (for instance, the equation may yield a value of 0.23 but the Code states that the minimum is 0.25). When this happens, the thickness is bigger than the equation computed value, so therefore the allowed fluid height is bigger than needed.

I can't answer the wind girder issue without looking at the data file.