Field Erected Fertilizer Storage Tanks and Using the API 650 Standard

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Most states have adopted containment regulations for liquid fertilizer operations using aboveground fertilizer tanks. Some state regulations specify a standard for new tank construction and others do not. API 650, the standard used by Heartland Tank LLC, is the internationally recognized standard for building field erected aboveground storage tanks (ASTs). The API 650 Standard was developed by the American Petroleum Institute and first published in 1961, but also had predecessor standards dating back to the 1930s. The committees assembled to create and subsequently revise the Standard for new technology and data have been comprised of the world’s best tank structural engineers. In addition to the engineers’ knowledge, the experience of tank owners and tank construction companies has also been incorporated in the revisions. Thus, the API 650 Standard is backed by over fifty years of testing.

The API 650 Standard covers the material, design, fabrication, assembly, and testing requirements for ASTs. While created by the petroleum industry, the Standard uses engineering principles for the design and construction of storage tanks for various uses. Due to the engineering expertise incorporated in API 650, The Fertilizer Institute and the Environmental Protection Agency have strongly recommended the Standard be used in all new fertilizer tank construction. Moreover, many leading insurance companies that insure fertilizer tanks are now requiring new tanks be built to the API 650 Standard as well as inspected by the API 653 Standard (Reconstruction and Inspection Specifications) before issuing or reissuing insurance policies.

Beyond its recognized engineering excellence, API 650 also provides you, the purchaser, with rights to ensure the Standard is followed: “The purchaser may conduct any investigation necessary to make certain that the manufacturer is in compliance with this standard, and the purchaser may reject any material that does not comply with this standard.” Section 4 of API 650 Standard.

So how can you verify that your tank construction company is adhering to the API 650 Standard? As the purchaser, you have the right to ask for documents from the construction company throughout the process to verify adherence to the Standard. These documents include:

  • Written Weld Procedures (prior to construction)
  • API 650 Shell Calculations
  • Mill Certifications
  • Certification of Welders or Welder Operators
  • Radiographic Reports
  • Letter from Tank Construction Company Certifying Tank Built to API 650 Specifications

Before contracting to have a tank built, the tank operator/owner should contemplate what basic design parameters he or she wants for the tank. First and foremost is what product will be stored in the tank first and in the future. Tanks have long service lives with adequate inspection, maintenance, and corrosion protection. Thus, the product stored in the tank will likely change due to changes in operation or technology. So consider building the tank for a higher specific gravity than the product that will initially be stored in the tank. This will ensure the ability to maximize the capacity of your tank.

A second consideration is the foundation of the tank. ASTs impart significant forces on the soil on which they sit, so the location of the tank and the corresponding soil condition is a critical factor in preventing excessive or uneven tank settlement. Figure out the history of the site and whether there are any structures under the soil (basements, wells, underground tanks, etc.). Voids created by these structures can cause uneven settling if the area is used as the tank foundation. The best condition for a tank foundation is an area of uniformly compacted ground containing a singular type of material. However, despite being uniform, some soil conditions, such as highly expansive clay and areas with high alluvial (sediment) deposits, can be problematic and require remediation. If the site history is unknown or poor soil conditions exist, a Geotechnical Investigation should be completed. A Geotechnical Investigation is the physical drilling and testing of the soils to determine the engineering properties. When using a Geotechnical firm, the engineer and/or tank builder should be involved to provide design loadings and acceptable settlement parameters.

A third consideration in building a tank is where to place the openings and equipment on the tank. The number, size, and location of tank nozzles should be determined in relation to the logistics of how and at what speed the tank will be filled. One must also determine the number of shell manways and placement. The number and location of the manways should be selected with logistics of the need to enter the tank as well as the possibility of an emergency exit. The size and location of the tank sump is another important decision in order for the tank to drain efficiently. Additional options for inclusion in the tank design are a sparge system and whether you intend on having an internal liner system for containment purposes. Taking the time now to deliberate on the matters of the products to be stored, the foundation, and the openings and equipment for the tank will aid in creating the best tank layout for your operation needs.

The API 650 Standard is one that will save you money in maintenance and repair costs over the life of the tank as well as provide the tank with a longer life span. You deserve to receive an API 650 Standard tank. Let Heartland Tank LCC show you how the API 650 Standard is done correctly and how it can benefit you as a tank owner.

 

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