API 653 Tank Inspection Consulting

ASNT Level III NDE authority for API 653-governed storage tanks. MFL and UT data, settlement surveys, remaining-life calculations, and code-defensible repair scope per API 653 Part 9 — supporting your own API 653 Authorized Inspector, for refineries, terminals and chemical plants worldwide. Affordable, accessible, fully customizable engagements.

Every NDE technique is interpreted under ASNT Level III authority; Atlantis is not an API 653 Authorized Inspector and does not sign the Inspection Report as inspector of record — that stays with your own Authorized Inspector, working from data Atlantis produces.

Atlantis is not an API 653 Authorized Inspector and does not sign as inspector of record. That role, and its sign-off authority under API 653 2018, stays with your own Authorized Inspector or Authorized Inspection Agency.

Code-defensible repair scope for bottom plate, shell plate and shell-to-bottom welds, with WPS / PQR review and qualified NDE re-test techniques.

UT, MT, PT, VT method authority for every NDE technique, so MFL, UT and surface-method findings reconcile against one method authority.

Anonymised — reference letters available under NDA.

Start with a 30-minute scoping call. We will tell you the inspection sequence, the NDE method stack, and the settlement-survey approach for your tank farm. Affordable, accessible, fully customizable engagements — quote on request.

What this page covers

From compliance check to integrity program
What you get
Methodology — how an API 653 engagement runs
Credentials backing every signed report
Industries served
Sample client outcomes
Engagement model
Frequently asked questions
Related consulting service lines
Ready to plan an API 653 campaign?

Key points covered

Routine and formal external inspections per API 653 2018 (5th Ed. + Addenda) — shell, roof, bottom course, foundation, settlement (cosine-curve + plane tilt), coating, ladders, gauges, valves. Output: signed external inspection report + recommended internal interval.
Bottom plate MFL scanning, shell course UT thickness grids, internal floating-roof seal inspections, sump & nozzle examinations, settlement re-survey, NDE re-test of repaired welds. Full out-of-service inspection report with remaining-life calculations.
Code-defensible repair scope per API 653 Part 9 — bottom plate replacement, shell plate replacement, shell-to-bottom weld repair, lap-patch versus butt-weld scope, anchor chair rebuild, settlement correction. Includes WPS / PQR review and qualified NDE techniques.
Survey-grade settlement measurement (cosine curve + plane tilt + edge settlement) per API 653 Annex B — analysed against acceptance criteria with predictions for the next inspection interval. Survey crew + Level III interpretation.
Calibrated MFL scanning (top-side + bottom-side discrimination) and follow-up UT confirmation on critical-zone plate, lap welds and sketch plates. Plate-by-plate corrosion map with remaining-thickness statistics and re-inspection recommendation.
Equipment register review, prior inspection history, product service (crude, refined, ethanol, sour water, chemicals), customer code basis (API 653 2018, NFPA 30, OSHA 1910.106, EPA SPCC, PHMSA 195) and shutdown calendar.
NDE crew on-site for shell, roof, bottom course, foundation, settlement, coating, appurtenances — UT thickness grids and MT/PT on critical welds, findings handed to your API 653 Authorized Inspector.
Confined-space entry, bottom plate MFL scanning, shell course UT grids, nozzle inspections, NDE on previous repair welds, floating roof seal and pontoon inspection (where applicable).
Shell and bottom-plate thickness data reduced to corrosion rate & remaining life per API 653 6.4, with settlement results evaluated against API 653 Annex B.
Signed inspection report per API 653 Part 12 plus prioritised repair scope per API 653 Part 9 — bottom plate replacement, shell course replacement, settlement correction, anchor & nozzle work.
Indian chemical plant — internal inspection + repair scope for two stainless tanks
An Indian specialty chemicals plant had two stainless steel storage tanks (304L, 22-year-old) with suspected chloride-stress corrosion cracking on the shell-to-bottom weld. We ran the out-of-service inspection — PT on the inside, UT thickness mapping, dye-pen on critical welds — and authored the repair scope per API 653 Part 9. Result: SCC confirmed on tank 1 (shell-to-bottom weld replaced and re-tested per ASME V), tank 2 cleared for service for another 10 years.
Refineries — crude, distillate, gasoline, asphalt, slop, sour water (API 650 cone & dome roof, API 620 low-pressure)
Product terminals & bulk distribution (gasoline, diesel, jet, ethanol, biodiesel)
Chemical plants — solvents, acids, caustic, glycol, methanol (stainless steel, lined, glass-lined)
Tank farms for upstream production (oil & produced water tanks, NGL spheres = scope-adjacent)
LNG / cryogenic out-of-scope but adjacent cryo-water & refrigerant storage
API 650 is the construction code for new atmospheric storage tanks. API 653 (current edition: API 653 2018, 5th Edition with Addenda) is the in-service code — it covers external & internal inspection intervals, inspector qualifications, repair, alteration, dismantling and reconstruction of existing tanks. Every welded, atmospheric, vertical, cylindrical tank built originally to API 650 (or another recognised code) falls under API 653 the moment it enters service.
External inspection: maximum 5 years between formal inspections per API 653 6.3.2.2, supplemented by monthly visual surveys. Internal (out-of-service) inspection: interval set by corrosion rate but never longer than 20 years from the previous internal inspection (API 653 6.4.2.2). Both intervals can be extended via a documented RBI program per API 580/581 Annex 2.D — typically the right answer for large tank populations.
Can RBI per API 580/581 replace the API 653 fixed inspection interval?
Yes. API 653 6.3.4 explicitly allows RBI-based intervals as an alternative to the calendar default, provided the program meets API 580 minimums (documented damage mechanism review, LoF/CoF calculation, inspection effectiveness credit, re-assessment triggers, signed by qualified personnel).
Both — sequentially. MFL is the screening tool (fast, calibrated, sensitive to top-side vs. bottom-side wall loss). UT (manual or array) is the confirmation tool on indications above the action threshold, interpreted under ASNT Level III authority so MFL and UT findings reconcile against one method authority.
No. Atlantis is not an API 653 Authorized Inspector and does not sign the Inspection Report (API 653 Part 12) or the Repair/Alteration record (Part 9) as inspector of record — that role stays with your own API 653 Authorized Inspector or Authorized Inspection Agency.

Storage tank inspection service (API 653)

This section is for terminal, refinery and plant owners who have a tank coming out of service, or an external inspection due, and need the NDE done. Atlantis NDT performs the examinations an API 653 inspection relies on and hands the results to your API 653 Authorized Inspector, who remains the inspector of record.

Scope of the tank inspection service

For out-of-service inspections we carry out magnetic flux leakage (MFL) scanning of floor plates with ultrasonic follow-up to size and confirm indications, including critical-zone and sketch-plate areas near the shell. We add ultrasonic thickness surveys of shell courses, examination of shell-to-bottom welds and repaired welds with the surface methods (MT, PT, VT) the procedure calls for, and inspection of nozzles and sumps as scoped.

For external inspections we perform shell thickness surveys, visual examination of the shell, roof, foundation and appurtenances, and settlement measurement. Settlement results are presented against the criteria in API 653 Annex B so your Authorized Inspector can evaluate them.

Repair work generates its own examination scope: re-examination of repaired floor and shell welds, and examination of new plate welds. We write that scope with you once repairs are defined.

Codes and responsibilities

Work is performed to support inspection under API 653, with API 650 referenced where repairs or reconstruction follow new-construction requirements, and API 575 as the practice reference for tank inspection. Examination procedures follow ASME Section V methods written for tank conditions.

The responsibilities are kept clear: Atlantis produces and interprets the NDE data under ASNT NDT Level III authority; your API 653 Authorized Inspector evaluates it, sets the inspection interval and signs the inspection report. Engineering assessments beyond the inspection code stay with your engineers.

Deliverables: what the tank inspection report contains

Floor plate map showing MFL indications, UT follow-up readings and remaining thickness by plate, with top-side and bottom-side indications distinguished where the follow-up confirms it.
Shell course thickness readings by course and location, with the minimum per course identified.
Weld examination records for shell-to-bottom and repaired welds, with method, procedure and result.
Settlement survey data and plots referenced to API 653 Annex B.
Photographs and visual examination notes for the roof, shell, foundation and appurtenances in scope.
Procedures, calibration records, technician certification levels and the Level III review, ready for your Authorized Inspector's file.

Mobilisation and qualifications

Tank work is mobilised within North America; confirm the site, tank numbers, out-of-service window and confined-space requirements in your RFQ. Because tank outages are fixed by operations and cleaning contractors, we plan around your window rather than asking you to plan around ours.

Technicians are certified under an ASNT SNT-TC-1A written practice in the methods they perform, with procedures approved by an ASNT NDT Level III. The company founder, Anoop Rayavarapu, is ASNT NDT Level III and API 653 certified; on your job the Authorized Inspector role remains with your nominated inspector.

What we need from you

Tank list with diameter, height, product service, floor and shell plate thickness, and drawings where available.
Previous inspection reports and floor maps, so results can be compared and repaired areas identified.
Out-of-service window, cleaning status on arrival, gas-free certification and confined-space entry arrangements.
Name of your API 653 Authorized Inspector and the report format they need.
Any repairs already planned, so the re-examination scope can be included.

Frequently asked questions: API 653 Storage Tank Inspection Services

Does Atlantis act as our API 653 Authorized Inspector?

No. We perform and interpret the NDE; your API 653 Authorized Inspector evaluates the results, sets intervals and signs the inspection report.

Why is UT follow-up needed after MFL floor scanning?

MFL detects and ranks metal loss quickly but its depth estimates are indicative. Ultrasonic follow-up sizes the remaining thickness at the indications that matter for the evaluation.

Can the shell survey be done while the tank is in service?

Shell thickness surveys and external visual examination are normally done in service. Floor scanning needs the tank out of service, cleaned and gas-free.

Request a quote for api 653 storage tank inspection services or use the RFQ form below. See all inspection services and ASNT Level III consulting.

Request an inspection quote (RFQ)

Tell us the asset, the method, where it is, the governing code, your dates, the size of the job and the report you need. We reply with questions or a quote. Affordable, accessible, fully customizable — no published pricing.

Or email the same details to info@atlantisndt.com. Mobilisation: North America; confirm your location in your RFQ.