API St 650-2025 PDF

Full title and description

API STD 650:2025 — Welded Tanks for Oil Storage. This industry standard specifies minimum requirements for materials, design, fabrication, erection and inspection of vertical, cylindrical, aboveground welded storage tanks used for petroleum, petroleum products and other liquids at or near atmospheric pressure. It is intended as a purchaser/manufacturer specification to promote safe, economical tank construction and operation while allowing purchaser-specific requirements where needed.

Abstract

Establishes requirements for welded, vertical, cylindrical aboveground storage tanks (closed- and open-top) of various sizes and capacities where internal pressures approximate atmospheric conditions. Applies to tanks with uniformly supported bottoms and to non‑refrigerated service with maximum design temperatures up to 93 °C (200 °F). The 2025 edition updates materials, fabrication, inspection and testing guidance, and references companion API recommendations for overfill prevention and welding/inspection practices.

General information

• Status: Current (active standard).
• Publication date: August 2025 (Fourteenth Edition published 2025‑08 / 01 Aug 2025 in distributor listings).
• Publisher: American Petroleum Institute (API).
• ICS / categories: Petroleum and related technologies; fuels and storage (ICS 75.x) — typically classified under petroleum/storage equipment and related construction categories (commonly cross‑referenced with construction/building ICS groups).
• Edition / version: 14th edition (API STD 650:2025).
• Number of pages: 542 pages (standard text).

Scope

Specifies minimum requirements for material selection, tank design calculations, plate and weld details, fabrication and erection methods, welding procedures and qualifications, nondestructive examination, pressure and leak testing, corrosion protection and coatings, and final inspection and documentation for vertical, welded, aboveground storage tanks whose entire bottom is uniformly supported. Limits include non‑refrigerated service and maximum design temperatures generally up to 93 °C (200 °F); internal pressures are those approximating atmospheric pressure unless additional requirements are invoked.

Key topics and requirements

• Material requirements (plate, steels, allowable properties and traceability).
• Design rules for shell, roof and foundation interactions (including settlement/uniform support assumptions).
• Welding procedure specifications, welder qualifications and weld acceptance criteria.
• Fabrication and erection controls including dimensional tolerances and bolt/weld details.
• Inspection and NDE requirements (radiography, ultrasonic, visual, liquid penetrant as applicable).
• Hydrostatic and pneumatic testing procedures and acceptance criteria.
• Corrosion protection, coatings, linings and cathodic protection guidance where applicable.
• Requirements/annexes for floating roofs, leak detection, and interfaces with overfill prevention and site safety programs (references to API RP 2350 and other API documents).

Typical use and users

Used by tank owners/operators in oil & gas, terminals and bulk storage, engineering consultants, tank manufacturers and fabricators, quality and inspection organizations, regulatory bodies, and insurers. Typical applications include new tank procurement, shop and field fabrication, site erection, acceptance testing, and baseline documentation for operation and maintenance programs.

Related standards

Commonly used together with other API and industry documents such as API 620 (low‑pressure refrigerated tanks), API 653 (tank inspection, repair, alteration and reconstruction), API RP 577 (welding processes and metallurgy), API RP 2350 (overfill prevention for storage tanks), plus applicable ASME, NFPA and local building/fire codes and environmental regulations.

Keywords

API 650, welded tanks, oil storage, aboveground storage tanks (AST), tank design, tank fabrication, welding, inspection, hydrotest, floating roof, corrosion protection, API STD 650:2025.

FAQ

Q: What is this standard?

A: API STD 650:2025 is the American Petroleum Institute standard that sets minimum requirements for welded, vertical, aboveground storage tanks used for petroleum and similar liquid products.

Q: What does it cover?

A: It covers materials, design, fabrication, welding, erection, inspection, testing, coatings/corrosion protection and documentation for vertical cylindrical welded tanks whose bottoms are uniformly supported and used in non‑refrigerated service up to the stated temperature limits.

Q: Who typically uses it?

A: Tank owners/operators, design and consulting engineers, tank fabricators, field erectors, inspectors, certifying authorities and regulatory agencies; also used by purchasing/specification writers when procuring tanks.

Q: Is it current or superseded?

A: Current — the 2025 (14th) edition is the active version published in August 2025 and supersedes the 2020 edition and its errata. Confirm edition/use dates with API or national adoption references when preparing contract or regulatory documentation.

Q: Is it part of a series?

A: Yes — API 650 sits within API’s family of tank and storage standards and is commonly referenced alongside API 620 (low‑pressure tanks), API 653 (inspection/repair), and various API RPs addressing welding, testing and safety (for example API RP 577 and API RP 2350).

Q: What are the key keywords?

A: Welded tanks, API 650, aboveground storage tanks, tank design, tank fabrication, welding qualification, inspection, hydrostatic testing, floating roof, corrosion protection.