Re: API 620 verses 650 standard? In Reply to Robert P. at 00:08 Dec-22-2010 (Opening).
From: Stephen Crimaudo [mailto:email@example.com]
Sent: Tuesday, January 04, 2011 3:22 PM
To: Andersen, Leonard
Subject: FW: API 620 verses 650 standard?
The only way to answer this properly is to look at the Scope of API 620, API 650 and API 653, Basically though API 650 and API 620 are equally tough to comply with. The Standards are meant for different tanks with different operating pressures and temps. API 653 includes the inspection requirements.
1. Design and Construction of Large, Welded, Low-pressure Storage Tanks
API STANDARD 620, ELEVENTH EDITION, ADDENDUM 2, AUGUST 2010
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 Manufacturersubject to the approval of the Purchasers authorized representativeto 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 gases at temperatures not lower than 325°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
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.
2. Welded Tanks for Oil Storage
API STANDARD 650, ELEVENTH EDITION, ADDENDUM 2: NOVEMBER 2009, EFFECTIVE DATE: MAY 1, 2010
1.1.1 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
1.1.2 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 Purchasers
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.
1.1.3 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, or
2. 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.
1.1.4 All tanks and appurtenances shall comply with the Data Sheet and all attachments.
1.1.5 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.
1.1.6 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.
Tank Inspection, Repair, Alteration, and Reconstruction
API STANDARD 653, FOURTH EDITION, ADDENDUM 1, AUGUST 2010
1.1.1 This standard covers steel storage tanks built to API 650 and its predecessor API 12C. It provides minimum
requirements for maintaining the integrity of such tanks after they have been placed in service and addresses
inspection, repair, alteration, relocation, and reconstruction.
1.1.2 The scope is limited to the tank foundation, bottom, shell, structure, roof, attached appurtenances, and
nozzles to the face of the first flange, first threaded joint, or first welding-end connection. Many of the design, welding,
examination, and material requirements of API 650 can be applied in the maintenance inspection, rating, repair, and
alteration of in-service tanks. In the case of apparent conflicts between the requirements of this standard and API 650
or its predecessor API 12C, this standard shall govern for tanks that have been placed in service.
1.1.3 This standard employs the principles of API 650; however, storage tank owner/operators, based on
consideration of specific construction and operating details, may apply this standard to any steel tank constructed in
accordance with a tank specification.
1.1.4 This standard is intended for use by organizations that maintain or have access to engineering and inspection
personnel technically trained and experienced in tank design, fabrication, repair, construction, and inspection.
1.1.5 This standard does not contain rules or guidelines to cover all the varied conditions which may occur in an
existing tank. When design and construction details are not given, and are not available in the as-built standard,
details that will provide a level of integrity equal to the level provided by the current edition of API 650 must be used.
1.1.6 This standard recognizes fitness-for-service assessment concepts for evaluating in-service degradation of
pressure containing components. API 579-1/ASME FFS-1, Fitness-For-Service, provides detailed assessment
procedures or acceptance criteria for specific types of degradation referenced in this standard. When this standard
does not provide specific evaluation procedures or acceptance criteria for a specific type of degradation or when this
standard explicitly allows the use of fitness-for-service criteria, API 579-1/ASME FFS-1 may be used to evaluate the
various types of degradation or test requirements addressed in this standard.
1.2 Compliance with This Standard
The owner/operator has ultimate responsibility for complying with the provisions of this standard. The application
of this standard is restricted to organizations that employ or have access to an authorized inspection agency as
defined in 3.3. Should a party other than the owner/operator be assigned certain tasks, such as relocating and
reconstructing a tank, the limits of responsibility for each party shall be defined by the owner/operator prior to
If any provision of this standard presents a direct or implied conflict with any statutory regulation, the regulation shall
govern. However, if the requirements of this standard are more stringent than the requirements of the regulation, then
the requirements of this standard shall govern.
1.4 Safe Working Practices
An assessment shall be made of the potential hazards to which personnel may be exposed when conducting
internal tank inspections, making repairs, or dismantling tanks. Procedures shall be developed according to the
guidelines given in API 2015, API 2016, and API 2217A that will include safeguard for personnel health and
safety, prevention of accidental fires and explosions, and the prevention of property damage. Conformance to
permit procedures is an essential safe work practice for protection of personnel and property.Where welding and
hot work are involved, API 2009 states Except in areas specifically designated as safe for hot work, a hot work
permit shall be obtained before starting any work that can involve a source of ignition.
Special procedures may need to be developed for certain activities described in this standard that are not fully
covered by the referenced API publications; e.g. safety precautions for personnel accessing floating roof tanks that
are in service, or gas freeing the bottom side of a tank. Appendix B of API 2009 provides brief information on inerting
tanks. Use of inerting as a safety precaution should address personnel hazards introduced when using inert gas in
the workplace and implementation should be done in consultation with specialists that are familiar with such
processes. Finally, procedures must comply with any federal or state safety regulations pertaining to confined
spaces or any other relevant provisions.
Senior Associate, Standards
American Petroleum Institute
1220 L Street, NW
Washington, DC 20005-4070