If your fluid is hydrocarbon, I advise you to buy a current copy of API 650 " Welded Steel Tanks for Oil Storage". And if your fluid is water, please refer to AWWA standards. Note: For water storage you can apply the API 650 also.
__________________
It is better to be defeated on principles, than to win on lies!
First, finalize your requirements such as process fluid, operating temperature, operating ressure, pressure direction, installtion detail, expected service life etc.
Second, select a designer and a fabricator.
Third, Test the tank as per applicable service condition.