API 653 Tank Inspection Consulting

ASNT Level III NDE authority for API 653-governed storage tanks. MFL and UT data, tank-farm RBI per API 580/581, FFS per API 579-1, 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.

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.

Signed FFS assessments per API 579-1 / ASME FFS-1 2021 — Level 1, 2, 3 — for shell metal loss, LTA, settlement-induced stress and weld misalignment.

UT, MT, PT, VT method authority for every NDE technique, plus API 580/581 RBI programme design experience.

Anonymised — reference letters available under NDA.

Start with a 30-minute scoping call. We will tell you the inspection sequence, the NDE method stack, the settlement-survey approach and the RBI option 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.
Plant-wide risk-based inspection program covering atmospheric tanks (cone, dome, floating roof), low-pressure tanks and bulk product terminals. LoF per API 581 Annex 2.D (storage tank), CoF per API 581 Part 3 with release modelling, secondary containment credit and detection effectiveness.
Level 1, 2 and 3 FFS assessments for general metal loss, local thin areas (LTA), pitting corrosion, blisters, dents, weld misalignment, brittle fracture & fatigue — applied to shell, bottom plate, annular ring and roof. Signed by an API 579 practitioner.
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).
API 579 Level 1/2 assessment on shell metal loss, bottom plate LTA, settlement-induced stress, weld misalignment. Remaining corrosion rate & remaining life per API 653 6.4.
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.
Tank-farm RBI per API 580/581 Annex 2.D. Generates risk-ranked external + internal inspection intervals, replacing fixed-interval default schedules and reducing inspection spend 30-50%.
Gulf Coast refinery — 124-tank farm RBI program + first-cycle external inspections
A US Gulf Coast refinery wanted to consolidate inspection across 124 atmospheric tanks (crude, gasoline, distillate, slop). We delivered a tank-farm RBI program per API 580/581 Annex 2.D, ran 28 external inspections in the first 90 days, and rebuilt the inspection-interval schedule. Result: 38% reduction in annual inspection spend, two leaking bottom plates caught in time, full PHMSA audit defence pack ready.
An Eastern-Province GCC product terminal had three out of 18 tanks flagged for excessive plane tilt and edge settlement after a 25-year service interval. We mobilised a survey crew + an API 579 practitioner. Result: 11 tanks cleared by FFS Level 2 (no repair), 5 tanks scheduled for settlement correction at next out-of-service window, 2 tanks taken out of service for foundation rebuild. Customer avoided ~$6M of premature shell-plate replacement.
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.
Indonesian fuel terminal — RBI bottom-plate MFL campaign across 42 tanks
An Indonesian downstream operator wanted to risk-rank bottom-plate inspections across a 42-tank fuel distribution terminal. We deployed a calibrated MFL crew with a Level III interpreter. Risk-based prioritisation reduced internal-inspection scope from 42 to 19 tanks across the next 5-year cycle, with three high-risk tanks pulled forward for immediate inspection (one had through-wall pitting). Full audit-defence package delivered.
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). Atlantis NDT delivers tank-farm RBI programs sized to your equipment population and customer audit calendar.
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.