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Storage tanks are an essential element in the production, refining, transportation, and marketing of petroleum products. API maintains several documents that address the design, fabrication, operation, inspection, and maintenance of aboveground (AST’s) and underground (UST’s) storage tanks.
API storage tank standards are developed by committees of experienced tank designers, fabricators, owners, and operators that bring a wealth of accumulated knowledge from their respective companies. Although API standards cover many aspects of AST and UST design and operation, they are not all-inclusive. There are several organizations that publish standards on tank design, fabrication, installation, inspection, and repair that may be more appropriate in some instances than API standards Please refer to the following organizations for additional standards and specifications:

• American Society of Mechanical Engineers (ASME) – www.asme.org
• American Society for Testing and Materials (ASTM) – www.astm.org
• American Water Works Association (AWWA) – www.awwa.org
• International Code Council– www.iccsafe.org
• NACE International (Corrosion Engineers) – www.nace.org
• National Fire Protection Association (NFPA) – www.nfpa.org
• Petroleum Equipment Institute (PEI) – www.pei.org
• Steel Tank Institute (STI) – www.steeltank.com
• Underwriters Laboratories (UL) – www.ul.com

OTHER RESOURCES

Basis of Seismic Design Provisions for Welded Steel Oil Storage Tanks
By R. S. Wozniak and W. W. Mitchell, Presented at 43rd API Midyear Refining, May 7, 1978
(To download: Right-click on link and select "Save Target As . . ." )

USGS Earthquake Hazards Program - Information on worldwide earthquake activity, earthquake science, and earthquake hazard reduction.

The Independent Liquid Terminals Association - Provides a listing of equipment and services available to the Bulk Liquid Terminals Industry. It's express purpose is to provide terminal and tank farm owners with a quick and easy reference for locating valuable and needed services parts & equipment.

U.S. Environmental Protection Agency TANKS emission estimation software and information.

TANK FAQ’S

Q: Where are storage tanks used in the petroleum industry?
A: Storage tanks are found in most sectors of the petroleum industry. These include exploration & production, refining, marketing, and pipelines.

Q: What are the different types of storage tanks?
A: Storage tanks can be divided into two basic types: aboveground (AST) and underground (UST). AST’s are used in production, refining, marketing, and pipeline operations. UST’s are typically used in the marketing of gasoline at retail service stations.

Q: What are the API standards for construction of new UST’s?
A: Underwriters Laboratories Standards UL58, 1746 and 1316. Steel Tank Institute F841-91

Q: What are the API standards for construction of new AST’s?
A: Spec. 12B, Bolted Tanks for Storage of Production Liquids; Spec. 12D, Field Welded Tanks for Storage of Production Liquids; Spec. 12F, Shop Welded Tanks for Storage of Production Liquids; Spec. 12P, Fiberglass Reinforced Plastic Tanks; API 620, Design and Construction of Large, Welded, Low-Pressure Storage Tanks; API 650, Welded Steel Tanks for Oil Storage.

Q: What is the difference between tanks constructed to the API 12 series specifications for production operations and API 650 tanks?
A: Production tanks are usually much smaller than API 650 tanks and are often subject to different operating conditions.

Q: What size tanks are covered by API refining, marketing, and pipeline standards?
A: Generally, the minimum size is 1100 gallons (4164 liters). API design standards for AST’s in refining, marketing, and pipeline facilities do not specify a maximum size.

Q: What are the API standards for the inspection and repair of AST’s currently in-service?
A: Spec. 12R1, Setting, Maintenance, Inspection, Operation, and Repair of Tanks in Production Service; API 653, Tanks Inspection, Repair, Alteration, and Reconstruction.

Q: Does API certify tank manufacturers?
A: Yes, to Specifications 12B, 12D, and 12F.  API does not certify manufacturers to Std. 650 at this time.

Q: Does API issue a certificate to verify that a tank has been built to API 620 or 650?
A: No. The manufacturer is responsible for certifying that the tank has been constructed in accordance with API 650 (see API 650, Section 8.3)

Q: How do I get my tank certified by API to Standard 620 or 650?
A: API no longer certifies tanks built to API 620 or 650. The API Monogram Program does include tanks built to Specifications 12B, 12D, and 12F.

Q: Can API provide assistance or consultation on tank design or inspection?
A: No. API does not act as a consultant on specific engineering problems or on the general application of its standards. API will provide an interpretation of the requirements in the standard and will address suggested changes based on new data or technology. Please refer to API 620, Appendix J; API 650, Appendix D; or API 653, Appendix E for further information in interpretations.

Q: Does API provide nameplates for API 650 tanks?
A: No. The tank manufacturer typically provides the nameplate for a new tank (see API 650, Section 8.1).

Q: Does API certify companies to do tank repair?
A: No. API only certifies inspectors to API 653.

Q: Where can a find an API 653 certified inspector?
A: A list of companies that employ certified inspectors can be found on the API Inspector Certification website.

Q: Does API 650 or 653 have procedures for hydrotesting?
A: No. Although both documents have requirements on when a hydrotest must be performed, they do not have procedures on how a hydrotest is performed.

Q: Where can I find a list of technical interpretations?
A: See the answers to previous inquiries page.