Format at a glance
| Item | Detail |
|---|---|
| Questions | 170 multiple choice: 140 scored, 30 unscored pretest items |
| Parts | 110 closed-book questions, then 60 open-book questions |
| Time | 7.5-hour day: tutorial, 2.75 hours closed book, 45-minute lunch, 3.75 hours open book |
| Delivery | In person at Prometric test centers only |
| Pass mark | Scaled score of 400 on a 200 to 500 scale; raw cut score not published |
| Windows (2027) | January 2-22, May 7-28 and September 3-24 |
What's on the effectivity sheet
For the September 2026, January 2027 and May 2027 exams, API lists: API 510 (11th Edition, 2022, with errata), RP 571 (15 named mechanisms only), RP 572, RP 576, RP 577, RP 578, the 2025 ASME Boiler and Pressure Vessel Code (Section V Articles 1, 2, 6, 7 and 23 SE-797; Section VIII Division 1 Introduction, UG, UW, UCS and Appendices 1-4, 6, 8 and 12; Section IX welding only) and selected articles of ASME PCC-2 (2022). Check the sheet for your own window, because editions change.
The calculations you must know
- Corrosion rate, remaining life, remaining corrosion allowance and inspection intervals (API 510, Sections 6 and 7). These may be asked closed book.
- Joint efficiency from UW-11 and Table UW-12, including RT-1 to RT-4 nameplate markings.
- Static head at 0.433 psi per foot, and vessel versus part MAWP (UG-98).
- Shell and head thickness and MAWP: UG-27(c)(1), UG-27(d) and UG-32 (ellipsoidal and hemispherical heads).
- Hydrostatic and pneumatic test pressures (UG-99 and UG-100) and impact test exemptions (UG-20(f), UCS-66).
- Fillet weld throat and leg (0.7 factor) and attachment weld sizes at openings (UW-16).
See where you stand in 10 minutes
Take the free API 510 practice test. 15 questions, every answer explained.
What isn't tested
The Body of Knowledge excludes, among others: external pressure calculations, wind and earthquake loads, flange and tubesheet calculations, relief valve sizing, cryogenic vessels below −50°F (−45°C), and API 510 Section 9 (natural resource vessels). Use the exclusion list to cut your reading.
A 10-week plan
- Weeks 1-2: API 510 itself, plus corrosion rate and interval calculations until you can do them from memory.
- Weeks 3-4: Section VIII calculations (UG-27, UG-32, UW-12, UG-99) with practice problems in both US and SI units.
- Weeks 5-6: Section IX WPS/PQR/WPQ review, RP 577 and RP 578.
- Weeks 7-8: RP 571 mechanisms, RP 572, RP 576 and Section V; first full timed mock.
- Weeks 9-10: open-book drills using PDF search, your mistakes bank, a second full mock, then light review.
Frequently asked questions
How many questions are on the API 510 exam?
170 multiple-choice questions, of which 140 are scored: 110 in the closed-book part and 60 in the open-book part.
Can I bring my own code books?
No. Papers, notes and books aren't allowed at Prometric. The code sections listed on the effectivity sheet are provided as PDFs on screen during the open-book part.
What is the API 510 passing score?
API reports a scaled score from 200 to 500, and 400 is the passing scaled score for all ICP exams. The number of correct answers needed varies slightly between exam forms and isn't published.
Can I take the API 510 exam online?
No. API lists the API 510 exam as in person at designated Prometric test centers only.
Official sources
Practice tests for these certifications
This guide is general information, checked November 2026, not legal advice. API rules change; confirm with API before you apply.
