EXAM GUIDE · CHECKED 16 SEPTEMBER 2026
API 653 Exam Guide
API 653 Aboveground Storage Tank Inspector exam for November 2026 and the 2027 windows: format, eligibility, the effective publications — which change between 2026 and 2027 — and how to prepare for the closed- and open-book parts. Every exam fact on this page comes from API's own documents, linked at the bottom. Where API has not published something, this page does not guess.
Exam format
| Questions | 170 in total: 140 scored and 30 unscored pretest questions |
|---|---|
| Split | 110 closed-book, 60 open-book |
| Exam day | 7.5 hours: a short tutorial, 2.75 hours closed-book, a 45-minute lunch break, 3.75 hours open-book |
| Delivery | Computer-based, in person at Prometric test centres |
| Open-book references | PDFs of the relevant codes and standards are provided on screen, in English |
| Results | Score report from Prometric by email within 24 hours; final result in the API ICP portal within 3 business days |
| Retake | Not in the same exam window — book the next window |
| Certification | API 653 certification is valid for three years, then recertification |
Time per question
The two parts are timed separately, and the time available per question is very different. Worked out from API's published timings:
CLOSED-BOOK
1.5min per question
110 questions in 165 minutes
OPEN-BOOK
3.8min per question
60 questions in 225 minutes
Eligibility
API sets a minimum amount of experience that depends on your education, and issues the certification only once your application has no open deficiencies.
| EDUCATION | EXPERIENCE | IN |
|---|---|---|
| BS or higher in engineering or technology, or 3+ years of military technical training | 1 year | Supervision or performance of inspection activities as described in API 653 |
| 2-year degree or certificate, or 2 years of military technical training | 2 years | Design, construction, repair, operation or inspection of aboveground storage tanks — 1 year of it in supervision or performance of inspection |
| High school diploma | 3 years | Design, construction, repair, operation or inspection of aboveground storage tanks — 1 year of it in supervision or performance of inspection |
| No formal education | 5+ years | Design, construction, repair, operation or inspection of aboveground storage tanks — 1 year of it in supervision or performance of inspection |
Publications examined
These are the editions on API's effectivity sheets. Where API limits the exam to certain sections, the list says so — anything outside those sections is not examined. The documents are copyrighted; buy them from an authorised seller.
For March, July and November 2026
API RP 571, Damage Mechanisms Affecting Fixed Equipment in the Refining Industry
3rd Edition, March 2020
- Section 2: Terms and Definitions
- 3.8 Atmospheric Corrosion
- 3.11 Brittle Fracture
- 3.14 Caustic Corrosion
- 3.15 Caustic Stress Corrosion Cracking (Caustic Embrittlement)
- 3.19 Concentration Cell Corrosion
- 3.22 Corrosion Under Insulation (CUI)
- 3.28 Ethanol Stress Corrosion Cracking
- 3.45 Microbiologically Influenced Corrosion (MIC)
- 3.57 Soil Corrosion
- 3.62 Sulfuric Acid Corrosion
API RP 575, Inspection Practices for Atmospheric and Low-Pressure Storage Tanks
5th Edition, September 2024
API RP 576, Inspection of Pressure-relieving Devices
5th Edition, September 2024
- Sections 4.3.2 and 6.7 only
API RP 577, Welding Processes, Inspection, and Metallurgy
3rd Edition, October 2020
API Standard 650, Welded Tanks for Oil Storage
13th Edition, March 2020, Errata 1 (January 2021)
API RP 651, Cathodic Protection of Aboveground Petroleum Storage Tanks
5th Edition, August 2024
API RP 652, Lining of Aboveground Petroleum Storage Tank Bottoms
5th Edition, May 2020
API Standard 653, Tank Inspection, Repair, Alteration, and Reconstruction
5th Edition, November 2014, Addendum 1 (April 2018), Addendum 2 (May 2020), Addendum 3 (November 2023), Errata 1 (March 2020), Errata 2 (February 2025)
ASME BPVC Section V, Nondestructive Examination
2023 Edition
- Articles 1, 2, 6, 7 and 23 (Section SE-797 only)
ASME BPVC Section IX, Qualification Standard for Welding, Brazing, and Fusing Procedures; Welders; Brazers; and Welding, Brazing, and Fusing Operators
2023 Edition
- Welding only
For March, July and November 2027
Changed from 2026: API 650 moves to the 14th Edition, RP 652 to the 6th Edition, the ASME code to the 2025 Edition, and API 653, RP 575, RP 576 and RP 577 gain new addenda or errata.
API RP 571, Damage Mechanisms Affecting Fixed Equipment in the Refining Industry
3rd Edition, March 2020
- Same sections and mechanisms as 2026
API RP 575, Inspection Practices for Atmospheric and Low-Pressure Storage Tanks
5th Edition, September 2024, Addendum 1 (July 2025), Addendum 2 (June 2026)
API RP 576, Inspection of Pressure-relieving Devices
5th Edition, September 2024, Addendum 1 (February 2026)
- Sections 4.3.2 and 6.7 only
API RP 577, Welding Processes, Inspection, and Metallurgy
3rd Edition, October 2020, Errata 1 (September 2025)
API Standard 650, Welded Tanks for Oil Storage
14th Edition, August 2025
API RP 651, Cathodic Protection of Aboveground Petroleum Storage Tanks
5th Edition, August 2024
API RP 652, Lining of Aboveground Petroleum Storage Tank Bottoms
6th Edition, December 2025
API Standard 653, Tank Inspection, Repair, Alteration, and Reconstruction
5th Edition, November 2014, Addenda 1–4 (April 2018, May 2020, November 2023, July 2025), Errata 1 (March 2020), Errata 2 (February 2025)
ASME BPVC Section V, Nondestructive Examination
2025 Edition
- Articles 1, 2, 6, 7 and 23 (Section SE-797 only)
ASME BPVC Section IX, Qualification Standard for Welding, Brazing, and Fusing Procedures; Welders; Brazers; and Welding, Brazing, and Fusing Operators
2025 Edition
- Welding only
How to prepare
Check which edition list applies to your exam date
Unlike the current API 510 and API 570 lists, API 653's editions change between the 2026 and 2027 windows. A November 2026 candidate studies API 650 13th Edition, RP 652 5th Edition and the 2023 ASME code; from March 2027 it is API 650 14th Edition, RP 652 6th Edition and the 2025 ASME code, with further addenda to API 653, RP 575, RP 576 and RP 577. Buy and mark up the set for your own window.
Closed book is API 653 and the tank recommended practices
About a minute and a half per question with no references. Inspection intervals, responsibilities, repair and alteration rules from API 653, and the practices in RP 575, 651 and 652, are what reward knowing by heart. Only ten damage mechanisms from RP 571 and two short parts of RP 576 are examined, so keep those in proportion.
Open book is API 653 and API 650 side by side
Nearly four minutes per question, spent mostly finding the right clause and table. Tank candidates work between API 653's evaluation rules and API 650's construction requirements, with Section IX for welding procedure questions. The references are on-screen PDFs, so practise searching the PDFs rather than tabbing paper copies.
Practise the two parts separately
Fast recall and careful lookup are different skills, and mixing them in one session hides which one is weak. Drill each on its own, then sit a full timed paper with the lunch break in the middle.
PRACTISING WITH ASSETRONX
The API 653 bank has 4,703 questions — 4,116 closed-book and 587 open-book — each with its answer, the reasoning and the clause it comes from, plus 10 full mock exams timed like the real day. Questions are grouped by publication, so you can work through one document at a time.
| PUBLICATION | CLOSED BOOK | OPEN BOOK |
|---|---|---|
| API 653 | 747 | 175 |
| API 650 | 80 | 90 |
| API RP 575 | 427 | 30 |
| API RP 577 | 718 | 48 |
| ASME Section IX | 529 | 127 |
| ASME Section V | 456 | 57 |
| API RP 571 | 444 | 20 |
| API RP 651 | 313 | 20 |
| API RP 652 | 312 | 20 |
| API RP 576 | 90 | 0 |
Questions
How many questions are on the API 653 exam?
170: 140 scored questions and 30 unscored pretest questions, split into 110 closed-book and 60 open-book questions.
Which edition of API 650 should I study?
It depends on your exam date. API's sheet for March, July and November 2026 lists API 650 13th Edition (March 2020, Errata 1 January 2021). Its sheet for March, July and November 2027 lists API 650 14th Edition (August 2025).
How long is the API 653 exam?
The exam day is 7.5 hours: a short tutorial, 2.75 hours for the closed-book part, a 45-minute lunch break and 3.75 hours for the open-book part.
When do I get my result?
Prometric emails a score report within 24 hours for most computer-based exams, and the final result reaches the API ICP portal within 3 business days.
If I fail, can I retake it in the same window?
No. API does not allow a retest in the same exam window; you reschedule for the next window.
How long is API 653 certification valid?
Three years, after which it has to be recertified.
Sources
Checked on 16 September 2026. API updates these documents for each exam window; if anything here differs from API's current documents, API is right.
- API — API 653 Aboveground Storage Tank Inspector certification page
- API — API 653 Publications Effectivity Sheet, March, July and November 2026
- API — API 653 Publications Effectivity Sheet, March, July and November 2027
- API ICP — Introducing Instant Scoring (results and retest policy)
AssetronX is an independent exam preparation provider and is not affiliated with or endorsed by the American Petroleum Institute. API 653 is a certification of the American Petroleum Institute.