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.

Definition

API 653 inspectors must be certified by API. Internal inspection includes floor scanning by MFL or UT, shell thickness mapping, and roof inspection. Floor minimum thickness calculations and remaining life determination use API 653 methodology.

Related terms

  • 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.
  • 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.
  • Magnetic Flux Leakage (MFL) — MFL is an electromagnetic NDT method that magnetizes a ferromagnetic component to saturation and detects flux leakage at metal-loss features using Hall-effect or coil sensors, widely used for tank-floor and pipeline pig inspection.
  • T-min (Minimum Thickness) — T-min is the minimum acceptable in-service wall thickness, equal to the larger of the pressure-design minimum and the structural-stability minimum, used as the threshold below which equipment must be repaired or retired.

Further reading

api 653 storage tank inspector certification

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.