API St 620-2013 (2021) PDF

Full title and description

St API St 620-2013 (2021) — API Standard 620: Design and Construction of Large, Welded, Low‑Pressure Storage Tanks (base standard published 2013, with addenda issued through 2021). This listing reflects the API Std 620:2013 technical content as issued by the American Petroleum Institute and the translated/adopted presentation sometimes shown as "St API St 620-2013 (2021)".

Abstract

API Std 620 provides rules, design methods, fabrication and inspection requirements for large, field‑erected, welded storage tanks intended for low‑pressure service (gas/vapor space pressures up to about 15 psig) and for products handled at temperatures down to cryogenic levels. The standard addresses material selection, toughness requirements for low temperatures, welding and qualification, structural design for loads (including wind and seismic), hydrostatic/pressure testing, nondestructive examination and corrosion‑protection measures; it also includes addenda and normative/informative annexes that extend applicability to specific cryogenic and refrigerated storage applications.

General information

• Status: Active.
• Publication date: Base standard published 2013 (API Std 620:2013); addenda issued through 2021 (notably Addendum 3, March 2021).
• Publisher: American Petroleum Institute (API).
• ICS / categories: 75.200 (Petroleum products and natural gas handling equipment); related classification 23.020.10 (stationary containers and tanks).
• Edition / version: 12th edition (API Std 620:2013, with subsequent addenda).
• Number of pages: Approximately 330–335 pages (published versions commonly cited at 332 pages).

Scope

Applies to the design, fabrication, erection and testing of large, welded, field‑assembled storage tanks intended for low‑pressure service (internal gas/vapor pressures up to about 15 psig) and for storage of liquids at temperatures ranging from near ambient down to cryogenic service (annexes give guidance for very low temperatures). The standard covers vertical, cylindrical tanks and provides rules for wall, roof and bottom design, materials and toughness requirements, welding procedure and qualification, nondestructive examination, pressure/hydrostatic testing and corrosion protection; it excludes pressure vessels designed for internal pressures above the specified limit.

Key topics and requirements

• Design pressure limit and classification (up to ~15 psig) and corresponding design methods for shell, roof and bottom.
• Low‑temperature (cryogenic) material selection and impact/toughness requirements for steels used in refrigerated service.
• Welding procedure specifications, welder/qualification requirements and weld inspection (NDE) practices.
• Structural design for environmental loads (wind, seismic, snow) and consideration of settlement and foundation effects.
• Testing and commissioning: hydrostatic and pressure testing, leak testing and acceptance criteria.
• Corrosion protection, coatings and cathodic protection guidance where applicable.
• Annexes and addenda that clarify cryogenic applications, special design cases and technical updates (addenda through 2021).

Typical use and users

Used by tank designers and structural/mechanical engineers, tank manufacturers and fabricators, construction contractors erecting field‑assembled tanks, owner/operators of petroleum, petrochemical and LNG storage facilities, inspection and certification bodies, and regulators establishing minimum design and inspection requirements. It is typically referenced when tanks must contain low‑pressure vapors or refrigerated/cryogenic liquids where API 650 (atmospheric tanks) is not appropriate.

Related standards

Commonly used alongside or compared with API Std 650 (Welded Tanks for Oil Storage) and API Std 653 (Tank Inspection, Repair, Alteration, and Reconstruction). Other related documents include API Std 2350 (overfill prevention), NFPA 59A (LNG), relevant ASME codes and regional regulations that govern storage of flammable or cryogenic liquids. When applying API 620, users often consult these complementary standards for inspection regimes, fire and safety requirements and operational controls.

Keywords

API 620; storage tanks; low‑pressure tanks; welded tanks; cryogenic storage; refrigerated storage; LNG tanks; tank design; welding qualification; hydrostatic test; tank inspection; API standards.

FAQ

Q: What is this standard?

A: API Std 620 is an industry standard published by the American Petroleum Institute that specifies requirements for the design and construction of large, field‑erected, welded storage tanks for low‑pressure service (base edition 2013 with addenda through 2021).

Q: What does it cover?

A: It covers material selection and toughness for low temperatures, structural and shell/roof/bottom design for tanks operating up to about 15 psig, welding procedures and qualifications, nondestructive examination, testing and commissioning, and corrosion protection—plus annexes/addenda for cryogenic and special cases.

Q: Who typically uses it?

A: Tank designers and engineers, manufacturers/fabricators, construction contractors, site owners/operators (petroleum, petrochemical, LNG and chemical plants), inspection authorities and regulators. Engineers choose API 620 when storage conditions exceed the material/temperature/pressure capabilities intended for atmospheric‑type tank standards.

Q: Is it current or superseded?

A: The base edition is API Std 620:2013 (12th edition). The document has received addenda (including one in 2021); the standard is generally listed as active for use, but users should confirm the specific addenda/errata applicable to their project and check API or their national standards body for any newer revisions or later addenda before final design.

Q: Is it part of a series?

A: It is part of the API family of tank and storage standards and is commonly used in the same technical domain as API Std 650 and API Std 653; readers often treat these standards together when specifying storage tank design, inspection and repair requirements.

Q: What are the key keywords?

A: Storage tanks, welded tanks, low‑pressure, cryogenic, LNG, tank design, welding, NDE, hydrostatic testing, API 620.