Shop-Fabricated Storage Tanks

Horizontal pressure vessels Vertical pressure vessels Storage tanks, shop fabricated Storage tanks, field erected... 

For inspection of large field-erected tanks, API 653, Tank Inspection, Repair, Alteration, and Reconstruction, is referenced by the US EPA. A certified inspector must inspect tanks. US EPA references the Steel Tank Institute Standard SPOOl-06, Standard for Infection of In-Service Shop Fabricated Aboveground Tanks for Storage of Combustible and Flammable Liquids, as an industry standard that may assist an owner or operator with the integrity testing and inspection of shop-fabricated tanks. The STI SPOOl-06 standard includes inspec-... 

Development of optimum sizes for tanks and dikes comes through trial and error. Considerations include the availabiliw of real estate, the po.ssible use of standard-sized tanks for. smaller capacities, and the nature of potential foundation design problems caused by early tank-size seleaions. The de.signer should refer to API 12F for standardized shop-fabricated tank sizes. Larger field-fabricated storage tanks must be sized to suit each site. 

Cone-Roof Tanks. Cone-roof tanks are cylindrical shells having a vertical axis of symmetry. The bottom is usually flat and the top made ia the form of a shallow cone. These are the most widely used tanks for storage of relatively large quantities of fluid because they are economic to build and the market supports a number of contractors capable of building them. They can be shop-fabricated ia small sizes but are most often field-erected. Cone-roof tanks typically have roof rafters and support columns except ia very small-diameter tanks when they are self-supporting (see Fig. 4b and c Table 3). 

Atmospheric Tanks The term atmospheric tank as used here applies to any tank that is designed to operate at pressures from atmospheric through 3.45 kPag (0.5 psig). It may be either open to the atmosphere or enclosed. Atmospheric tanks may be either shop-fabricated or field-erected. The most common apphcation is storage of fuel for transportation and power generation. See the subsections Pressure Tanks and Pressure Vessels later in this section. 

Abovegroimd Storage Tanks Aboveground storage tanks are classified as either field-erected or shop-fabricated. The Tatter is typically 190-m (50,000-gal) capacity or less and is able to be shipped over the highway, while larger tanks are more economically erected in the field. Whereas field-erected tanks likely constitute the majority of total AST storage capacity, shop-fabricated ASTs constitute the clear majority of the total number of ASTs in existence today Most of these shop-fabricated ASTs store flammable or combustible liquids at atmospheric pressure and have 45-m (12,000-gal) capacity or smaller. 

UL 2085, Protectedf Aboveground Tanks for Flammable and Combustible Liquids, covers shop-fabricated, aboveground atmospheric protected tanks intended for storage of stable, flammable or combustible liquids that have a specific gravity not greater than 1.0 and that are compatible with the material and construction of the tank. 

The Steel Tank Institute (STI) publishes construction standards and recommended installation practices pertaining to ASTs fabricated to STI technologies. STI s recommended installation practices are notable for their applicability to similar respective technologies SPOOl-06, Standard for Inspection of In-Service Shop Eabricated Aboveground Tanks for Storage of Combustible and Elammable Liquids... 

R912-00, Installation Instructions for Shop Fabricated Abovegroimd Storage Tanks for Flammable, Combustible Liquids... 

The revised mle also states that all bulk storage container installations mnst provide a secondary means of containment for the entire capacity of the largest single container, with sufficient freeboard to contain precipitation, and that such contaimnent is sufficiently impervious to contain discharged oil. US EPA encourages the use of industry standards to comply with the rules. Many ovmers of shop-fabricated tanks have opted for double-wall tanks built to STI or UL standards as a means to comply with this requirement. 

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