A tank farm is a controlled explosion waiting for a mistake. The spacing rules are not bureaucratic-they are the difference between a contained incident and a chain reaction. Layout decisions made at the drawing stage are almost impossible to correct later.
Minimum spacing between tanks
Fixed cone roof, flammable liquid: 0.5 × diameter of the larger tank, minimum 15 m (NFPA 30)
Internal floating roof: 0.4 × diameter, minimum 15 m
External floating roof: 0.4 × diameter, minimum 15 m
LPG spheres: 1.5 × diameter or 20 m, whichever is greater
Water/fire water tanks: no fire-spacing requirement, but keep 3 m for access
Spacing to bund walls
The bund wall must contain 110 % of the largest tank volume (NFPA 30) or 100 % plus rainfall (GB 50160). The distance from tank shell to bund wall must allow access for firefighting and maintenance-typically 3–7 m. A bund that is too close traps heat and makes foam application impossible.
Spacing to buildings and boundaries
To occupied buildings: 15–30 m depending on tank type and building occupancy
To site boundary: 15 m minimum for flammable liquid tanks
To public road: 30 m for large tanks
To ignition sources (boilers, flares): 30–60 m depending on vapor pressure
Practical layout rules
Group tanks by product class-do not mix crude and LPG in one bund
Place fire water tank at the highest elevation to allow gravity feed
Route piping in a common trench with expansion loops, not over the bund
Keep a 6 m clear lane around the farm for fire trucks
Locate the control room upwind and outside the vapor dispersion zone
FAQ snippet
"Can I reduce spacing if I use foam monitors?" No. Foam systems reduce fire severity but do not change the radiation and vapor dispersion physics that drive spacing rules. The only way to reduce spacing is to use smaller tanks or a different roof type.
A layout that passes the spacing check is the cheapest insurance a tank farm owner can buy-it costs nothing at the drawing stage and prevents a chain-reaction fire at the operating stage.
