During the 1990’s a series of costly aboveground fertilizer tank failures prompted companies to begin an aggressive assessment of large tanks in their inventory in an effort to determine whether these tanks were fit for service. In addition, as a result of these failures, several state regulatory agencies began to examine current regulations for the aboveground storage of liquid fertilizer, and, where no regulations existed, to consider promulgating such regulations. The Fertilizer Institute (TFI) is the national trade association representing the fertilizer industry. At the direction of the TFI’s Executive Committee, a Tank Integrity Work Group was established in September 2000 to review the issue of inspection and maintenance of large non-pressurized liquid fertilizer tanks. In 2001, TFI issued Aboveground Storage Tanks of Liquid Fertilizer – Recommended Inspection Guidelines representing the consensus of the Tank Integrity Working Group, which set forth suggested, uniform industry inspection and maintenance guidelines. As the result of a large catastrophic liquid fertilizer tank failure on Nov. 12, 2008, in Chesapeake, Va., the U.S. Chemical Safety and Hazard Investigation Board (CSB) conducted an investigation and issued a report on its findings and recommendations. Among the recommendations was for TFI to do more outreach to encourage the use of its guidelines and to encourage its members who contract for liquid fertilizer storage to incorporate the use of its guidelines in contracts. In view of the CSB recommendation and at the direction of TFI’s Executive Committee, a UAN Working Group was convened in 2009 to review, and where appropriate, update the guidelines. As recognized, site-specific conditions may require deviations from these guidelines. Ultimately, it is the responsibility of the tank owner and operator, in consultation with an authorized inspector, to implement the appropriate inspection and maintenance protocols to ensure tank integrity. TFI, including its members, the members of the Tank Integrity Task Force, the 2009 UAN Working Group, the inspectors and the companies and organizations that employ them, in furnishing or distributing this information, do not make any warranty or representation, either express or implied, with respect to the accuracy, completeness, or utility; nor do they assume any liability of any kind whatsoever resulting from the use or reliance upon any information, material or procedure contained herein, including but not limited to any claims for damages, loss or injury regarding health, safety, environmental effects or performance. In general, the Tank Integrity Work Group and the UAN Working Group recommend that all new tanks should be designed and built to American Petroleum Institute (API) Standard 650 and 3
inspections of existing tanks should be based upon API Standard 653, but with modifications for the unique characteristics of a tank storing liquid fertilizer. API Standard 653 can be used as a general guideline for inspection of any aboveground storage tank. For example, tanks that were not built to API Standard 650 criteria or that have been modified subsequently such that they now do not comply with API Standard 650, may still be inspected under the API Standard 653 inspection guidelines. Whether or not the tank was built to API Standard 650 criteria, inspectors of aboveground storage tanks should advise whether the owner/operator may continue service without modification or whether the owner/operator must make repairs to the tank or have the tank further evaluated prior to continuing service. The following practices, as written, pertain specifically to tanks constructed of carbon or stainless steel or aluminum. Tanks utilizing alternate methodologies or materials should be designed and constructed in accordance with standards substantially similar in scope to that of API Standard 650. These tanks should be maintained and inspected based upon standards related to the original construction standard. The scope of inspections should be based upon the related standards, or in their absence, API Standard 653 should be used as a general guideline. The tank inspection should include a recommendation regarding suitability for continued service. The inspection types and frequencies found in these practices should be followed. The construction, repair, maintenance and inspection considerations, as well as the recordkeeping recommendations contained herein still apply and should be followed as applicable to the alternate design.
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