Civil Engineering Association

API 620:2009 Design and Construction of Large, Welded, Low-pressure Storage Tanks

The API Downstream Segment has prepared this standard to cover large, field-assembled storage tanks of the type
described in 1.2 that contain petroleum intermediates (gases or vapors) and finished products, as well as other liquid
products commonly handled and stored by the various branches of the industry.
The rules presented in this standard cannot cover all details of design and construction because of the variety of tank
sizes and shapes that may be constructed. Where complete rules for a specific design are not given, the intent is for
the Manufacturer—subject to the approval of the Purchaser’s authorized representative—to provide design and
construction details that are as safe as those which would otherwise be provided by this standard.
The Manufacturer of a low-pressure storage tank that will bear the API 620 nameplate shall ensure that the tank is
constructed in accordance with the requirements of this standard.
The rules presented in this standard are further intended to ensure that the application of the nameplate shall be
subject to the approval of a qualified inspector who has made the checks and inspections that are prescribed for the
design, materials, fabrication, and testing of the completed tank.
1.2.1 This standard covers the design and construction of large, welded, low-pressure carbon steel above ground
storage tanks (including flat-bottom tanks) that have a single vertical axis of revolution. This standard does not cover
design procedures for tanks that have walls shaped in such a way that the walls cannot be generated in their entirety
by the rotation of a suitable contour around a single vertical axis of revolution.
1.2.2 The tanks described in this standard are designed for metal temperatures not greater than 250°F and with
pressures in their gas or vapor spaces not more than 15 lbf/in.2 gauge.
1.2.3 The basic rules in this standard provide for installation in areas where the lowest recorded 1-day mean
atmospheric temperature is –50°F. Appendix S covers stainless steel low-pressure storage tanks in ambient
temperature service in all areas, without limit on low temperatures. Appendix R covers low-pressure storage tanks for
refrigerated products at temperatures from +40°F to –60°F. Appendix Q covers low-pressure storage tanks for
liquefied hydrocarbon gases at temperatures not lower than –270°F.
1.2.4 The rules in this standard are applicable to tanks that are intended to (a) hold or store liquids with gases or
vapors above their surface or (b) hold or store gases or vapors alone. These rules do not apply to lift-type gas
holders.
1.2.5 Although the rules in this standard do not cover horizontal tanks, they are not intended to preclude the
application of appropriate portions to the design and construction of horizontal tanks designed in accordance with
good engineering practice. The details for horizontal tanks not covered by these rules shall be equally as safe as the
design and construction details provided for the tank shapes that are expressly covered in this standard.
1.2.6 Appendix A has been deleted.
1.2.7 Appendix B covers the use of plate and pipe materials that are not completely identified with any of the
specifications listed in this standard.
1.2.8 Appendix C provides information on subgrade and foundation loading conditions and foundation construction
practices.
1.2.9 Appendix D provides information about imposed loads and stresses from external supports attached to a tank
wall.
1.2.10 Appendix E provides considerations for the design of internal and external structural supports.
1.2.11 Appendix F illustrates through examples how the rules in this standard are applied to various design
problems.
1.2.12 Appendix G provides considerations for service conditions that affect the selection of a corrosion allowance;
concerns for hydrogen-induced cracking effects are specifically noted.
1.2.13 Appendix H covers preheat and post-heat stress-relief practices for improved notch toughness.
1.2.14 Appendix I covers a suggested practice for peening weldments to reduce internal stresses.
1.2.15 Appendix J is reserved for future use.
1.2.16 Appendix K provides considerations for determining the capacity of tank venting devices.
1.2.17 Appendix L covers requirements for the design of storage tanks subject to seismic load.
1.2.18 Appendix M covers the extent of information to be provided in the Manufacturer’s report and presents a
suggested format for a tank certification form.
1.2.19 Appendix N covers installation practices for pressure- and vacuum-relieving devices.
1.2.20 Appendix O provides considerations for the safe operation and maintenance of an installed tank, with
attention given to marking, access, site drainage, fireproofing, water draw-off piping, and cathodic protection of tank
bottoms.
1.2.21 Appendix P summarizes the requirements for inspection by method of examination and the reference
paragraphs 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.
1.2.22 Appendix Q covers specific requirements for the materials, design, and fabrication of tanks to be used for the
storage of liquefied ethane, ethylene, and methane.
1.2.23 Appendix R covers specific requirements for the materials, design, and fabrication of tanks to be used for the
storage of refrigerated products.
1.2.24 Appendix S covers requirements for stainless steel tanks in non-refrigerated service.
1.2.25 Appendix U covers detailed rules for the use of the ultrasonic examination (UT) method for the examination
of tank seams.

API 620:2009 (Addendum-2 2010) Design and Construction of Large, Welded, Low-pressure Storage Tanks

This package contains Addendum 2 of API Standard 620, Design and Construction of Large, Welded, Low-pressure Storage Tanks, Eleventh Edition. This package consists of the pages that have changed since the March 2009 printing of Addendum 1.

To update your copy of API Standard 620, replace, delete, or add the following ages as indicated:

Part of Book Changed Old Pages to be Replaced New PagesCover front and back overs front and back covers
Front Matter...... Title page to Addendum 1.....Title page to Addendum 2
-----------------------vii–ix + blank--------------vii–ix + blank
Section--1....................1-1–1-2...........................1-1–1-2
Section--2....................2-1–2-4...........................2-1–2-4
Section--4....................4-3–4-10.........................4-3–4-10
Section--5....................5-3–5-8...........................5-3–5-8
Section--6....................6-3–6-4...........................6-3–6-4
Section--7....................7-5–7-6...........................7-5–7-6
Appendix-I....................I-1 + blank........................I-1 + blank
Appendix-Q...................Q-1–Q-26.........................Q-1–Q-26
Appendix-R...................R-1–R-18..........................R-1–R-19 + blank
Appendix-S...................S-7–S-8...........................S-7–S-8

API Std 620 Addendum 1 , API Std 620 Addendum 2 , API Std 620 Addendum 3
official site, free download...

For those who don't have time to shuffle the pages to insert the Addendums, here is the complete document (272 pages) dated 2012 incorporating the 3 Addendums:


Regards

can anyone share the API 620 Twelfth Edition, Includes Addendum 1 (2014) and Addendum 2 (2018)