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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. 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.
• 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
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:
1. all of the requirements given in this Standard in SI units,
2. all of the requirements given in this Standard in US
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
All tanks and appurtenances shall comply with the Data Sheet and
• 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 (½ in.), including any corrosion allowance, and whose
design metal temperature exceeds the minimums stated in the
Appendix AL provides requirements for aluminum tanks.
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.
• Appendix I provides acceptable construction details that 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 provides requirements covering the complete shop
assembly of tanks that do not exceed 6 m (20 ft) in diameter.
Appendix K provides a sample application of the
variable-design-point method to determine shell-plate
• Appendix L provides the Data Sheet and the Data Sheet
instructions for listing required information to be used by the
Purchaser and the Manufacturer. The use of the Data Sheet is
mandatory, unless waived by the Purchaser.
Appendix M provides requirements for tanks with a maximum design
temperature exceeding 93°C (200°F) but not exceeding 260°C
Appendix N provides requirements for the use of new or unused
plate and pipe materials that are not completely identified as
complying with any listed specification for use in accordance with
Appendix O provides recommendations for the design and
construction of under-bottom connections for storage tanks.
• Appendix P provides requirements for design of shell openings
that conform to Tables 5-6a and 5-6b that are subject to external
piping loads. An alternative or supplemental design may be agreed
upon by the Purchaser or Manufacturer.
Appendix R provides a description of the load combinations used
for the design equations appearing in this Standard.
Appendix S provides requirements for stainless steel tanks.
Appendix SC provides requirements for mixed material tanks using
stainless steel (including austenitic and duplex) and carbon steel
in the same tank for shell rings, bottom plates, roof structure,
and other parts of a tank requiring high corrosion resistance.
Appendix T summarizes the requirements for inspection by method
of examination and the reference sections within the Standard. The
acceptance standards, inspector qualifications, and procedure
requirements are also provided. This appendix is not intended to be
used alone to determine the inspection requirements within this
Standard. The specific requirements listed within each applicable
section shall be followed in all cases.
Appendix U provides requirements covering the substitution of
ultrasonic examination in lieu of radiographic examination.
Appendix V provides additional requirements for tanks that are
designed to operate under external pressure (vacuum)
• Appendix W provides recommendations covering commercial and
documentation issues. Alternative or supplemental requirements may
be mutually agreed upon by the Manufacturer and the Purchaser.
Appendix X provides requirements for duplex stainless steel
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