scope:

General: This standard covers material, design, fabrication, erection, and testing requirements for vertical, cylindrical, aboveground, closed- and open-top, welded steel 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 1.1.9). This standard applies only to tanks whose entire bottom is uniformly supported and to tanks in nonrefrigerated service that have a maximum operating temperature of 200°F (see 1.1.16).

This standard is designed to provide the petroleum industry with tanks of adequate safety and reasonable economy for use in the storage of petroleum, petroleum products, and other liquid products commonly handled and stored by the various branches of the industry. 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 done. When such decisions and actions are taken, they are to be specified in documents such as requisitions, change orders. data sheets, and drawings.

The appendixes of this standard contain requirements, alternative requirements, purchaser requirements (when so specified), nonmandatory recommendations and information. See Table 1-1 for the status of each appendix.

Appendix A provides for an alternative (and simplified) tank in which the stressed components, such as shell plates and reinforcing plates, are limited to a maximum nominal thickness of H inch, including any corrosion allowance, and to the minimum design metal temperatures stated in the appendix.

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

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

Appendix D explains how technical inquiries regarding this standard shall be prepared for submission to the director of the Manufacturing, Distribution and Marketing Department.

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 purchaser.

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

Appendix G provides requirements for an optional aluminum dome roof.

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

Appendix I provides basic recommendations, which may be specified by the purchaser, for design and construction of tank and foundation systems that provide leak detection and subgrade protection in the event of tank bottom leakage, and provides for tanks supported by grillage.

Appendix J presents requirements covering the complete shop assembly of tanks that do not exceed 20 feet in diameter.

Appendix K provides a sample application of the variable-design-point method to determine shell-plate thicknesses.

Appendix L provides data sheets to be used by the purchaser in ordering a storage tank and by the manufacturer upon completion of construction of the tank.

Appendix M provides additional requirements for tanks with maximum operating temperatures from 200'F to 500°F.

Appendix N provides requirements for the use of new or unused plate and pipe materials that are not completely identified by this standard as complying with any listed specification.

Appendix O contains recommendations for the design and construction of under-bottom connections for storage tanks.

Appendix P presents minimum recommendations for design of shell openings that conform to Table 3-8 that are subject to external piping loads. An alternative or supplemental design may be agreed upon by the purchaser or manufacturer.

Appendix S provides additional requirements for stainless steel tanks.