- Petroleum storage tanks should be located in dyke enclosure with roads all around.
- Pump station and piping manifold shall not be installed within dyke enclosure. They can be installed outside the dyke area by the side of the road.
- The aggregate capacity of the tanks placed in one dyke enclosure shall not exceed 60000 m³ for a group of fixed roof tanks and 120000 m³ for a group of floating roof tanks.
- If a group of tanks contains both fixed and floating roof tanks, then need to treat as the fixed-roof tanks only to not exceeds the limits of 60000 m³ for safety.
- Fixed cum floating roof tanks shall be considered as fixed roof tanks. Though, if the fixed cum floating roof tanks are equipped with windows opening on the shell and these windows will not get blocked at any cost, then these may be treated as floating roof tanks.
- The dyked enclosure should be able to accommodate the complete contents or product of the largest tank in the dyke in case of any failure in the rank or the piping system connected to it.
- The dyke enclosure capacity is calculated after deducting the volume of all the tanks (other than the largest tank) and the tank pads, foundations, and the stairs present within the dyke up to the height of the dyke wall.
- While calculating the dyke wall height, a freeboard of 200 mm is added to the calculated liquid level or dyke wall height.
- The dyke or dike wall height(including the freeboard of 200 mm) shall be a minimum of 1 m and a maximum of 2 m from the inside finish grade level.
- The dyke encloser or the dike wall can be made up of earth, concrete, or solid masonry, but it should be able to withstand the hydrostatic load.
- Earthern dyke wall width (flat section on top, not the inclined one) shall not be less than 0.6 m to ensure the stability of the dyke wall.
- For the excluded petroleum product storage tank, the capacity of dyke encloser should be based on spill containment only and not for containment of tank rupture.
- In the case of excluded petroleum, the minimum height of dyke wall shall be 0.6 m.
- The separation distance between the two nearest tanks located in separate dyke encloser shall not be less than the diameter of the larger of the two tanks or 30 m, whichever is more is considered.
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