EXAM GUIDE · CHECKED 16 SEPTEMBER 2026
API 510 Exam Guide
API 510 Pressure Vessel Inspector exam for September 2026 – May 2027: format, eligibility, the effective publications and which sections are examined, 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 | 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 |
| 2-year associate degree or 2 years of military technical training | 2 years | Design, fabrication, repair, operation or inspection — including 1 year of supervision |
| High school diploma | 3 years | Design, fabrication, repair, operation or inspection — including 1 year of supervision |
| No formal education | 5+ years | Design, fabrication, repair, operation or inspection — including 1 year of supervision |
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 September 2026, January 2027 and May 2027
API 510, Pressure Vessel Inspection Code: In-service Inspection, Rating, Repair, and Alteration
11th Edition, October 2022, Errata 1 (March 2023), Errata 2 (2025)
API RP 571, Damage Mechanisms Affecting Fixed Equipment in the Refining Industry
3rd Edition, March 2020
- Section 2: Terms and Definitions
- 3.3 Amine Stress Corrosion Cracking
- 3.8 Atmospheric Corrosion
- 3.9 Boiler Water and Steam Condensate Corrosion
- 3.11 Brittle Fracture
- 3.14 Caustic Corrosion
- 3.15 Caustic Stress Corrosion Cracking
- 3.17 Chloride Stress Corrosion Cracking
- 3.22 Corrosion Under Insulation
- 3.27 Erosion/Erosion-Corrosion
- 3.35 High-temperature H2/H2S Corrosion
- 3.36 High-temperature Hydrogen Attack
- 3.37 Hydrochloric Acid Corrosion
- 3.46 Naphthenic Acid Corrosion
- 3.61 Sulfidation
- 3.67 Wet H2S Damage (Blistering/HIC/SOHIC/SSC)
API RP 572, Inspection Practices for Pressure Vessels
5th Edition, November 2023
API RP 576, Inspection of Pressure-relieving Devices
5th Edition, September 2024
API RP 577, Welding Processes, Inspection, and Metallurgy
3rd Edition, October 2020, Errata 1 (September 2025)
API RP 578, Material Verification Program for New and Existing Assets
4th Edition, February 2023
ASME Boiler and Pressure Vessel Code, Section V, Nondestructive Examination
2025 Edition
- Articles 1, 2, 6, 7 and 23 (Section SE-797 only)
ASME BPVC Section VIII, Division 1, Rules for Construction of Pressure Vessels
2025 Edition
- Introduction (U), UG, UW, UCS, Appendices 1–4, 6, 8 and 12
ASME BPVC Section IX, Qualification Standard for Welding, Brazing, and Fusing Procedures; Welders; Brazers; and Welding, Brazing, and Fusing Operators
2025 Edition
- Welding only
ASME PCC-2, Repair of Pressure Equipment and Piping
2022
Each referenced Article and its Appendices:
- 101 Scope, Organization, and Intent
- 201 Butt-Welded Insert Plates in Pressure Components
- 202 External Weld Buildup to Repair Internal Thinning
- 209 Alternatives to Postweld Heat Treatment
- 210 In-Service Welding Onto Carbon Steel Pressure Components or Pipelines
- 211 Weld Buildup, Weld Overlay, and Clad Restoration
- 212 Fillet Welded Patches
- 215 Repair Welding Considerations for Cr-Mo Steel Pressure Vessels
- 216 Welded Hot Taps in Pressure Equipment or Pipelines
- 304 Flaw Excavation and Weld Repair
- 305 Flange Repair and Conversion
- 312 Inspection and Repair of Shell and Tube Heat Exchangers
- 501 Pressure and Tightness of Piping and Equipment
- 502 Nondestructive Examination in Lieu of Pressure Testing for Repairs and Alterations
How to prepare
Start from the effectivity sheet, not from a textbook
Everything examined is on API's publication list, and several documents are only partly in scope: fifteen damage mechanisms plus the definitions from RP 571, five articles of ASME V, named parts of VIII-1, fourteen articles of PCC-2. Time spent on the rest does not come back on the day. Mark the in-scope sections in your own copies first.
Closed book is recall of API 510 and the recommended practices
At 165 minutes for 110 questions you have about a minute and a half each, with no references. That rewards knowing inspection intervals, responsibilities, repair and alteration rules and damage mechanism basics well enough to answer without deriving them. Drill these by publication until the numbers stop being new.
Open book is navigation and arithmetic
225 minutes for 60 questions is nearly four minutes each, and most of it goes on finding the right paragraph in VIII-1, PCC-2 or Section IX and working the numbers. The references come as on-screen PDFs, so practise searching the PDFs themselves — paper tabs do not help on the day. Typical work includes minimum required thickness, MAWP, remaining life and inspection intervals, pressure test values, joint efficiency and reviewing a WPS against its PQR.
Practise the two parts separately
The skills do not transfer much: fast recall on one side, careful lookup and calculation on the other. Mixing them in one practice session hides which one is weak. Work each part on its own, then sit at least one full timed paper with the lunch break in the middle to feel the length of the day.
PRACTISING WITH ASSETRONX
The API 510 bank has 6,091 questions — 5,409 closed-book and 682 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 510 | 1,431 | 124 |
| ASME PCC-2 | 731 | 74 |
| API RP 577 | 662 | 8 |
| API RP 572 | 509 | 12 |
| ASME Section IX | 503 | 97 |
| ASME Section V | 461 | 53 |
| API RP 571 | 444 | 12 |
| ASME Section VIII, Div. 1 | 411 | 294 |
| API RP 576 | 239 | 5 |
| API RP 578 | 18 | 3 |
Questions
How many questions are on the API 510 exam?
170: 140 scored questions and 30 unscored pretest questions that API is trialling. They are split into 110 closed-book and 60 open-book questions.
How long is the API 510 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.
Can I bring my own code books to the open-book part?
API states that PDF documents of the pertinent codes and standards are available on the computer during the open-book portion. Check the candidate information from API and Prometric for the current rules before your exam.
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. API can withhold instant scoring in the window after an exam is revalidated and says it notifies candidates in advance when that applies.
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 510 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 510 Pressure Vessel Inspector certification page
- API — API 510 Exam Publications Effectivity Sheet, September 2026, January 2027 and May 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 510 is a certification of the American Petroleum Institute.