scope:

GENERAL

This Standard establishes minimum requirements for material, design, fabrication, erection, and testing for vertical, cylindrical, aboveground, closed- and open-top, welded storage tanks in various sizes and capacities for internal pressures approximating atmospheric pressure (internal pressures not exceeding the weight of the roof plates), but a higher internal pressure is permitted when additional requirements are met (see 1.1.12). This Standard applies only to tanks whose entire bottom is uniformly supported and to tanks in non-refrigerated service that have a maximum design temperature of 93°C (200°F) or less (see 1.1.19).

• This Standard is designed to provide industry with tanks of adequate safety and reasonable economy for use in the storage of petroleum, petroleum products, and other liquid products. This Standard does not present or establish a fixed series of allowable tank sizes; instead, it is intended to permit the Purchaser to select whatever size tank may best meet his needs. This Standard is intended to help Purchasers and Manufacturers in ordering, fabricating, and erecting tanks; it is not intended to prohibit Purchasers and Manufacturers from purchasing or fabricating tanks that meet specifications other than those contained in this Standard.

Note: A bullet (•) at the beginning of a paragraph indicates that there is an expressed decision or action required of the Purchaser. The Purchaser's responsibility is not limited to these decisions or actions alone. When such decisions and actions are taken, they are to be specified in documents such as requisitions, change orders, data sheets, and drawings.

• This Standard has requirements given in two alternate systems of units. The Manufacturer shall comply with either:

all of the requirements given in this Standard in SI units, or

all of the requirements given in this Standard in US Customary units.

The selection of which set of requirements (SI or US Customary) to apply shall be a matter of mutual agreement between the Manufacturer and Purchaser and indicated on the Data Sheet, Page 1.

All tanks and appurtenances shall comply with the Data Sheet and all attachments.

• Field-erected tanks shall be furnished completely erected, tested, and ready for service connections, unless specified otherwise. Shop-fabricated tanks shall be furnished tested and ready for installation.

• The appendices of this Standard provide a number of design options requiring decisions by the Purchaser, standard requirements, recommendations, and information that supplements the basic standard. Except for Appendix L, an appendix becomes a requirement only when the Purchaser specifies an option covered by that appendix or specifies the entire appendix. See Table 1-1 for the status of each appendix.

Appendix A provides alternative simplified design requirements for tanks where the stressed components, such as shell plates and reinforcing plates, are limited to a maximum nominal thickness of 12.5 mm (¹/₂ in.), including any corrosion allowance, and whose design metal temperature exceeds the minimums stated in the appendix.

Appendix B provides recommendations for the design and construction of foundations for flat-bottom oil storage tanks.

Appendix C provides minimum requirements for pontoon-type and double-deck-type external floating roofs.

Appendix D provides requirements for submission of technical inquiries regarding this Standard.

• Appendix E provides minimum requirements for tanks subject to seismic loading. An alternative or supplemental design may be mutually agreed upon by the Manufacturer and the Purchaser.

Appendix F provides requirements for the design of tanks subject to a small internal pressure.

Appendix G provides requirements for aluminum dome roofs.

Appendix H provides minimum requirements that apply to an internal floating roof in a tank with a fixed roof at the top of the tank shell.