The metal used in all tanks shall be of a minimum gauge, U.S. standard, depending upon the capacity or size as given in the following table:

Capacity	Thickness
(Gallons)	of material
1 to 500	14 gauge
501 to 1100	12 gauge
1101 to 4000	7 gauge
4001 to 10500	1/4 inch
10501 to 20000	5/16 inch
20001 to 30000	3/8 inch