There is a small semantic issue here..a problem of terminology.

Although this is called a tank on a PID or on a process datasheet this is not a tank (as per API 650), Because it is not vertical , not flat bottom etc..
because of the very low internal pressure , this is not a pressure vessel ( as per ASME VIII)

Such non-ASME vessel would be designed as per good practice for instance according UL 142
Standard for Steel Aboveground Tanks for Flammable and Combustible Liquids

this is not a big issue providing you ensure and check:
1- Do you have a have a vacuum or partial vacuum case ? check with your process people please.
2- when you add saddles ( two) underneath your tank make sure that one is sliding to allow one side of this tank to expand freely and avoid thermal loads
3- make sure that you use elliptical heads , because flat heads for such diameters will get thick very quickly.

you can use PVelite and enter all your infos and get the weight and the loads

all in all you will get small overturning moments and only the tank + its weight will count really , I suggest you enter 1 bar = 0.1 N/mm2 as internal pressure , you enter your vacumm if any , seismic , wind ..you will get the weight, you can calculate with a density of 1 , select a saddle from PV elite data base
I expect you to have a thickness of about 5 to 6 mm including corrosion allowance and try to avoid flat heads (also hard to weld)

good luck
And salam to all