General 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. Coverage 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. The tanks described in this standard are designed for metal temperatures not greater than 250 ??and with pressures in their gas or vapor spaces not more than 15 lbf/in.2 gauge. The basic rules in this standard provide for installation in areas where the lowest recorded 1-day mean atmospheric temperature is ?C50 ?? Annex S covers stainless steel low-pressure storage tanks in ambient temperature service in all areas@ without limit on low temperatures. Annex R covers low-pressure storage tanks for refrigerated products at temperatures from +40 ??to ?C60 ?? Annex Q covers low-pressure storage tanks for liquefied gases at temperatures not lower than ?C325 ?? 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. 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. Annex A describes how to submit inquiries and suggestions for changes to this standard. Annex 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 Annex C provides information on subgrade and foundation loading conditions and foundation construction practices. Annex D provides information about imposed loads and stresses from external supports attached to a tank wall. Annex E provides considerations for the design of internal and external structural supports. Annex F illustrates through examples how the rules in this standard are applied to various design problems. Annex G provides considerations for service conditions that affect the selection of a corrosion allowance; concerns for hydrogen-induced cracking effects are specifically noted. Annex H covers preheat and post-heat stress-relief practices for improved notch toughness. Annex I covers a suggested practice for peening weldments to reduce internal stresses. Annex J is reserved for future use. Annex K provides considerations for determining the capacity of tank venting devices. Annex L covers requirements for the design of storage tanks subject to seismic load. Annex M covers the extent of information to be provided in the Manufacturer's report and presents a suggested format for a tank certification form. Annex N covers installation practices for pressure- and vacuum-relieving devices. Annex 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. Annex 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 annex 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. Annex Q covers specific requirements for the materials@ design@ and fabrication of tanks to be used for the storage of liquefied gases such as ethane@ ethylene@ and methane. Annex R covers specific requirements for the materials@ design@ and fabrication of tanks to be used for the storage of refrigerated products. Annex S covers requirements for stainless steel tanks in non-refrigerated service. Annex SC provides requirements for mixed material tanks using stainless steel (including austenitic and duplex) and carbon steel in the same tank for walls@ bottom plates@ roof structure@ and other parts of a tank requiring added corrosion resistance. Annex U covers detailed rules for the use of the ultrasonic examination (UT) method for the examination of tank seams. Annex X covers materials@ design@ fabrication@ erection@ and testing requirements for aboveground@ welded@ duplex stainless steel storage tanks. Limitations General The rules presented in this standard apply to vertical@ cylindrical oil storage tanks built according to API 650 as specifically allowed in 5.7.1.8@ F.1@ and F.7 of that standard. These rules do not apply to tanks built according to rules established for unfired pressure vessels designated for an internal pressure greater than 15 lbf/in.2 gauge. Piping Limitations The rules of this standard are not applicable beyond the following locations in piping connected internally or externally to the walls1 of tanks constructed according to this standard. a) The face of the first flange in bolted flanged connections. b) The first threaded joint on the pipe outside the tank wall in threaded pipe connections. c) The first circumferential joint in welding-end pipe connections that do not have a flange located near the tank.
API STD 620-2013 history
2013API STD 620-2013 Design and Construction of Large@ Welded@ Low-pressure Storage Tanks (TWELFTH EDITION; ADD 1: November 2014)
2008API STD 620-2008 Design and Construction of Large@ Welded@ Low-pressure Storage Tanks (Eleventh Edition; Incorporating Addendum 1: March 2009; Addendum 2: August 2010)
2002API STD 620-2002 Design and Construction of Large@ Welded@ Low-Pressure Storage Tanks (Tenth Edition; Addendum 1: June 2004)
1996API STD 620-1996 Design and Construction of Large@ Welded@ Low-pressure Storage Tanks (Ninth Edition; Includes Addendum 1: December 1996 and Addendum 2: December 1997)
1990API STD 620-1990 Design and Construction of Large@ Welded@ Low-pressure Storage Tanks (Eighth Edition; Incorporating Errata: August 1992)
1982API STD 620-1982 Recommended Rules for Design and Construction of Large@ Welded@ Low-Pressure Storage Tanks (Seventh Edition; Incorporating Revision 1@ April 1985)
1978API STD 620-1978 Recommended Rules for Design and Construction of Large@ Welded Low-Pressure Storage Tanks (SIXTH EDITION)
1970API STD 620-1970 Recommended Rules for Design and Construction of Large@ Welded@ Low-pressure Storage Tanks (Fourth Edition)
1966API STD 620-1966 Recommended Rules for Design and Construction of Large@ Welded@ Low-Pressure Storage Tanks (FIFTH EDITION; SUPP 3: August 1975)
1963API STD 620-1963 RECOMMENDED RULES FOR DESIGN AND CONSTRUCTION OF LARGE@ WELDED@ LOW-PRESSURE STORAGE TANKS (SECOND EDITION)