API 650 Welded Tanks for Oil Storage

API 650 is the construction code for welded steel atmospheric storage tanks, defining materials, design, fabrication, welding, examination, and testing requirements for new tank construction.

Definition

API 650 specifies NDT requirements including 100% RT of shell vertical seams (or random per joint efficiency choice), 100% MT/PT of shell-to-bottom welds, and vacuum-box testing of bottom seams. Inspector certification is per API 653 for in-service work.

What this document is

The API standard for welded steel storage tanks for oil storage, covering design, materials, fabrication, erection and testing of new atmospheric tanks.

How it is applied

It governs new construction; API 653 governs inspection, repair, alteration and reconstruction in service. The relationship mirrors Section VIII to API 510.

The common misuse

Repairing an in-service tank to API 650 alone. Reconstruction and repair provisions live in API 653, and the differences matter for settlement, shell evaluation and floor assessment.

Where API 650 Welded Tanks for Oil Storage fits in an inspection programme

A term is only useful when it connects to a decision. API 650 Welded Tanks for Oil Storage appears in written procedures, in technique sheets, and in the records an owner or accreditation body reviews afterwards — which means the way it is defined in your documentation has to match the way it is applied on site. Where the two drift apart, audits find it. Atlantis writes and reviews procedures against the governing codes, trains inspection personnel to apply them, and builds the record-keeping that makes the evidence retrievable years later. Procedure development and code consulting · NDT training and certification · Ask us about your programme.

Related terms

API 653 Tank Inspection, Repair, Alteration, and Reconstruction — API 653 is the inspection, repair, alteration, and reconstruction code for above-ground welded steel storage tanks built to API 650, defining periodic external (5 yr), ultrasonic (10 yr), and internal (typically 10 yr) inspection intervals.
Storage Tank — A storage tank is a low-pressure, large-volume welded container for the storage of liquids — typically atmospheric (API 650), low pressure (API 620), or for water (AWWA D100) — inspected in service per API 653.
AWWA D100 Welded Carbon Steel Tanks for Water Storage — AWWA D100 is the welded carbon steel tank standard for water storage, defining materials, design, fabrication, welding, and NDT requirements for elevated, standpipe, and ground-supported water storage tanks.

More standard terms

ASME Section V · ASME Section VIII · ASME Section IX · ASME Section XI · ASME B31.1 Power Piping · ASME B31.3 Process Piping · ASME B31.8 Gas Transmission and Distribution Piping · ASME B31.4 Liquid Pipelines · API 510 Pressure Vessel Inspection Code · API 570 Piping Inspection Code

Where this comes up in practice

Terms like this one appear in three places that matter commercially: the written practice that governs how your personnel are qualified, the procedures and technique sheets that define how an examination is actually performed, and the evidence an auditor or client asks for when they want to know why an inspection was accepted. Getting the terminology right is the easy part; being able to produce the qualification record, the calibration traceability and the procedure revision that applied on the day of the inspection is the part that decides audits.

Atlantis NDT provides NDT training and certification against ASNT SNT-TC-1A and ISO 9712, ASNT Level III consulting for written practices and procedure approval, inspection management software that holds qualification, calibration and procedure-revision evidence in recoverable form, and an asset integrity platform that binds inspection results to the asset they describe. Browse the full NDT glossary or ask a Level III directly.