API 653 — Tank Inspection, Repair, Alteration, and Reconstruction

In-service inspection, repair, alteration, and reconstruction of aboveground storage tanks (AST) originally built to API 650 — bottom, shell, roof inspection.

Scope

API 653 — Tank Inspection, Repair, Alteration, and Reconstruction — is the in-service inspection code for aboveground storage tanks (ASTs) constructed to API 650 (welded steel tanks for oil storage). API 653 covers external inspection, in-service ultrasonic thickness measurement of the shell, internal inspection (typically requiring tank cleaning and entry), bottom thickness measurement (MFL — magnetic flux leakage scanning of the tank floor), repair and alteration provisions, and reconstruction of tanks moved to new locations. The current edition is the 6th Edition (April 2020) with Addendum 1 (2023). API 653 is one of the three major in-service inspection codes from API (510 for vessels, 570 for piping, 653 for tanks). Each has a counterpart certification — API 653 Storage Tank Inspector certification is required for the technical authority on tank inspection programs.

NDT methods it governs

{"label":"Ultrasonic Testing (UT)","href":"/blog/ultrasonic-testing"}
{"label":"CUI Detection","href":"/blog/corrosion-under-insulation-cui-detection-guide"}
{"label":"Risk-Based Inspection (RBI)","href":"/blog/risk-based-inspection-rbi-implementation-guide"}
{"label":"API 571 Damage Mechanisms","href":"/blog/api-571-damage-mechanisms-complete-industry-guide"}

Certifications that reference it

{"label":"API 653 Tank Inspector Certification","href":"/api-653-certification"}

Issuing body

API

Revision history

2023 —
2020 —
2014 —
2009 —

Related standards

api-510 · api-570 · api-571 · api-579 · api-580 · api-581 · aws-d1-1

Applying this in an inspection programme

Code compliance is only demonstrable if the evidence behind it is: the procedure revision in force, the inspector's certification state and the instrument's calibration status at the time of test. Atlantis NDT provides ASNT Level III consulting for procedure and written-practice work against this code, training toward the certifications that reference it, and inspection management software that keeps that evidence recoverable years later. Request a consultation.

How a standard like this is applied in an inspection programme

A standard is only half of the requirement. It defines how an examination is performed and, in some cases, how results are classified — but the acceptance criteria that decide whether a component stays in service normally come from the construction or in-service code governing the item, not from the examination standard itself. Confusing the two is one of the more common findings in a procedure review: a procedure that correctly cites the examination standard but applies acceptance criteria from the wrong code or the wrong edition.

What has to be in place for compliance to be demonstrable

A written procedure qualified against this standard for the specific materials, thickness ranges and geometries in scope — not a generic procedure covering everything
Personnel certified for the method and level under ASNT SNT-TC-1A, ANSI/ASNT CP-189, NAS 410 or ISO 9712, current on the date the examination was performed
Equipment, probes and reference standards in calibration on that date, with traceability to a national standard under ISO 17025
The applicable edition of the standard recorded against the examination, so historical work stays assessed under the edition then in force
Technique sheets under the same revision control as the procedure above them — the most frequently uncontrolled document in an otherwise compliant quality system

Edition changes

When a new edition is issued, new work moves to it from a defined effective date that you set and record; work already performed stays assessed under the edition in force at the time. Retrospectively applying a new edition to historical dispositions invalidates the original acceptance decision and creates a substantially larger problem than the one being solved.

Where this usually goes wrong

Not in the technical content, but in reconstruction. An auditor picks an issued report and asks which procedure revision applied, who performed the work and whether they were qualified on that date, and whether the instrument and reference blocks were in calibration. Programmes that hold only current state can answer none of those. Binding the document revision, the qualification state and the calibration state to each inspection record as it is created turns that from an investigation into a lookup.