Tank wall thickness help

[Net2014]

Respect to all,

please help with following problem:

Have to calculate the wall thickness for the Stainless steel Water tank.
I have found a lot of formulas and standards (rules), but I am confused because I get very different results.

Tables, in general, shown that minimum is around 2-3 mm, but I get (in general) almost triple of it or more....
Eg. - Thickness:
Pressure (water height x radius x density) x radius, all devided by stainless steel max.allowed stress. (425 MPa)

Sorry for my unknowledge for terms etc, just studing....
In addition, pic attached.

thank you very much,
Student

[Kelly_Bramble]

There are a bunch of pressure vessel calculators on Engineers Edge:

Pressure Vessel Design Calculators

These calculators will help you design to ASME Pressure Vessel Code. Other than these, I would see the pressure vessel asme section viii.