First roof design... what is my mistake? API 650 1

[monirri]

I am designing a tank whose calculations are already available on the internet but in an older version of API 650. Right now I am designing the roof, which is self supported cone roof. I am getting enormous thicknesses for the roof using The formula given in 5.10.5.1 of the last edition. if i use the formulas of former API 650 editions, all is good, result is 1.25mm. But latest edition introduces the use of the modulus of elasticity in the calculation. I take that value from ASME sec 2 PART D. I am getting enormous thicknesses at any angle. None is under 13mm. The following is the data. What is it that I am doing wrong?
Diameter is 3.99meters
Material is 304L

Values of thicknesses range from 22 to 77mm

What´s the problem?

Thanks in advance
Carlos Molina

 

[LittleInch]

Modulus elasticity is 189 X 10^3 MPa

Check your number in MPa is actually 189000.

A full calc would be useful te m rather than a spreadsheet sheet we can't see the formula you've used

 

[HTURKAK]

Assume B=1.5 kPa ( 150 kg/m2)
D=4.0 m
Theta =15 degr.

Min.t=( 2*1000*4/Sin 15) SQRT (1.5/(1.33*1000*189000)=2.38 mm so, in this case choose min 5.0 mm

Pls notice that the Modulus of elasticity ( at the table TM-1 is given ) E= 189 * 10 ^3=189000 MPa

 

[HTURKAK]

Modulus elasticity is 189 X 10^3 MPa

Check your number in MPa is actually 189000.

A full calc would be useful te m rather than a spreadsheet sheet we can't see the formula you've used

I was preparing my respond when you posted . When i post my reply i saw you are faster . ( Vorsprung durch Antwort ?) And a pink star for your quick respond . However the color of star missing with new set up.

 

[monirri]

Thank you so much, Misters. Yes, that´s th formula Mr HTURKAK. Thanl you very much.