Atmospheric Storage Tank — API 650 — Applicable Engineering Standards & Codes

Description

Welded above-ground atmospheric storage tank — global default for petroleum / chemical storage.

API 650 Welded Tanks for Oil Storage

Edition: 13th Edition (2020, A1 2021, A2 2023) Region: USA, Global

Atmospheric, vertical, cylindrical above-ground welded steel tanks for liquid storage.

Key requirements (11)

Atmospheric tanks — design pressure –0.25 in WC to 2.5 psig (≈17 mbar) max.
Design temperature: ambient up to 93 °C (200 °F); higher → API 620 Annex M.
Bottom plate min thickness: 6 mm (1/4") nominal.
Shell design: 1-foot method (Section 5.6.3) or variable design point (5.6.4).
Joint efficiency: 0.85 (lap-welded) or 1.0 (butt-welded with full RT).
Hydrotest: filled with water to design liquid level; 24-hour holding test.
Wind girders / top angle stiffeners: Section 5.9.6.
Annex E: seismic; Annex C: external floating roof; Annex H: internal floating roof.
Annex F: internal pressure up to 18 in WC; Annex M: elevated temperature; Annex S: stainless.
Default allowable stress: 2/3 yield or 2/5 UTS (whichever lower) at design temp.
Foundation: Annex B guidance (ringwall, slab, piled).

Note: Default global standard for atmospheric oil/petroleum storage tanks.

API 653 Tank Inspection, Repair, Alteration, and Reconstruction

Edition: 5th Edition (2014, A3 2020) Region: USA, Global

In-service inspection and repair of API 650 and 12C tanks.

Key requirements (7)

Applies to API 650 / API 12C atmospheric storage tanks in service.
External inspection ≤ 5 years; internal ≤ 10 years (extendable via RBI to 15–20 yr).
Bottom MFL/UT scanning during internal inspection — quantifies underside corrosion.
Settlement survey at intervals (cosine-curve fit, edge settlement criteria).
Reconstruction: hydrotest required after major shell replacement.
Authorized Tank Inspector (API 653 ICP) required.
Repairs categorized as 'Major Alteration', 'Repair' or 'Routine Maintenance' with different documentation.

API 575 Inspection Practices for Atmospheric and Low-Pressure Storage Tanks

Edition: 4th Edition (2020) Region: USA, Global

Inspection practice companion to API 653.

API 2000 / ISO 28300 Venting Atmospheric and Low-Pressure Storage Tanks

Edition: 7th Edition (2020) Region: USA, Global

Normal and emergency venting requirements for atmospheric and low-pressure tanks.

Key requirements (7)

Venting requirements for atmospheric & low-pressure tanks (also as ISO 28300).
Normal venting: thermal in-breathing (cooling) and out-breathing (heating + product movement).
Emergency venting: external fire exposure — table-based wetted-area heat input.
Heat input formula: Q = 21,000·F·A^0.82 (BTU/hr) where A = wetted area (ft²), F = environment factor.
Pilot-operated PV vents allowed in lieu of weighted pallet vents.
Maximum allowable pressure typically 2.5 psig (matches API 650 limit).
Combined pressure & vacuum venting capacity sized for worst-case scenario.

ASTM A516 / A516M Pressure Vessel Plates, Carbon Steel, for Moderate- and Lower-Temperature Service

Edition: A516/A516M-17 Region: USA, Global

Most-used carbon steel plate for pressure vessel shells (Gr 60, 65, 70).

ASTM A36 Standard Specification for Carbon Structural Steel

Edition: A36/A36M-19 Region: USA, Global

Common carbon structural steel — plates, shapes, bars.

ISO 28300 Petroleum, petrochemical and natural gas industries — Venting of atmospheric and low-pressure storage tanks

Edition: 2008 Region: Global

International equivalent of API 2000.

EN 14015 Site built, vertical, cylindrical, flat-bottomed, above ground welded steel tanks for storage of liquids at ambient temperature and above

Edition: 2004 (under revision) Region: Europe

European equivalent of API 650.

IS 803 Code of Practice for Design, Fabrication and Erection of Vertical Mild Steel Cylindrical Welded Oil Storage Tanks

Edition: 1976 (R2018) Region: India

Indian counterpart for atmospheric oil storage tanks (similar to API 650 in scope).

Key requirements (7)

Code of practice for design, fabrication and erection of vertical mild steel cylindrical welded oil storage tanks.
Indian counterpart of API 650.
Atmospheric storage; maximum design pressure typically 250 mm WC.
Joint efficiency: 0.85 (lap) or 1.0 (butt with full RT).
Hydrotest: water-fill to design liquid level, 24-hour hold.
Foundation: ringwall or slab per soil bearing capacity.
Used for crude, product, fuel oil storage in Indian refineries.