Section 22(3) in The Static And Mobile Pressure Vessels (Unfired) Rules, 1981
(3)The number of aboveground storage vessels in one group shall not exceed six. Spherical and cylindrical vessels shall be installed in separate groups. Minimum separation distance between two such groups of vessels shall be the distance from vessel to property line as mentioned in Table 1, 2 or 3, as the case may be, or thirty metres, whichever is less. Each such group of vessels shall be covered under separate license under these rules.
