Above ground storage tanks or AST’s are tanks that are positioned above the ground and are usually designed to hold liquids or gases. These tanks are generally made of metal and must follow a range of standards, including API 653, which is tank inspection, repair, alteration, and reconstruction. This code was developed by the American Petroleum Institute.

STI SP001 is another standard for above ground storage tanks, which was developed by the Steel Tank Institute/Steel Plate Fabricators Association in 2000. This standard covers requirements for inspection of small tanks erected in the field, welded metal, and tanks that are fabricated in the shop.

The federal government has 40 CFR 112, which also includes minimum requirements for the design of above ground storage tanks and how they are monitored and managed. Spill prevention, control, and countermeasure regulations are also in place for these tanks in case they should leak or rupture.

The Design of Above Ground Storage Tanks

There is a great deal of variety for the design of ASTs since they may be used in different industries. Eight basic types exist:

• Fixed-roof tanks

• External floating roof tanks

• Internal floating roof tanks

• Pressure tanks

• Variable vapor space tanks

• Horizontal tanks

• Domed external floating roof tanks

• Liquefied natural gas tanks

The tanks will include a containment basin, which acts as protection if a spill should occur. This basin must be built to withstand a great deal of pressure and to be resistant to the product inside the tanks. It must be built to hold the capacity of the largest tank along with ten percent of the sum of the other tanks’ capacities.