The API 510 Body of Knowledge, explained section by section
API publishes a Body of Knowledge for each exam window, together with a Publications Effectivity Sheet that lists the editions and the sections you can use. Read both for your window before you start studying. They change, and only the listed sections are available in the open-book part.
- Questions
- 170
- Time
- 390 minutes
- Exam fee
- Initial: 2026 $875 member / $1,125 non-member; 2027 $890 / $1,140. Late application $200. Reschedule (new window) $350
- Where
- Prometric computer-based test, in person at designated test centers only (API 510 is not available for remote testing)
The five sections
- I. Thickness measurements, inspection intervals and vessel integrity: the calculations. Corrosion rates, remaining life, intervals, minimum thickness, pressure and static head.
- II. Welding procedure and qualification evaluation: reviewing procedure specifications and qualification records against ASME Section IX, with API RP 577 for welding inspection practice.
- III. Nondestructive examination: the examination methods and acceptance requirements, drawing on ASME Section V, Section VIII Division 1 and API 510.
- IV. Practical knowledge, general: inspection planning, repairs and alterations, rerating and pressure testing under API 510.
- V. Practical knowledge, specific: the damage mechanisms listed from API RP 571 and the inspection practices in RP 572, RP 576 and RP 578, plus the listed PCC-2 repair articles.
API doesn't publish weights for these sections.
How to prepare
- Take the free diagnostic and start with whichever of section I or section V scores lowest. Those are the two broadest sections.
- Build a one-page method sheet for each calculation type and practice with fresh numbers until you don't need the sheet.
- Practice open-book lookups only in the sections on the effectivity sheet. Anything else won't be available on exam day.
- Apply before the window's deadline. An application is valid for 6 months from your first requested exam date.
Exam facts
| Questions | 170 total (140 scored + 30 unscored pretest); 110 closed-book + 60 open-book |
| Time | 390 minutes |
| Book | Closed-book part + open-book part; only the sections listed on the Publications Effectivity Sheet are available during the open-book part. Calculator, scratch paper and pencil provided; own papers and reference books not allowed |
| Passing | Scaled score 400 on a 200-500 scale (equated across forms) |
| Where you test | Prometric computer-based test, in person at designated test centers only (API 510 is not available for remote testing) |
| Code edition | API 510 11th ed. Oct 2022 (Errata 1 Mar 2023, Errata 2 2025); RP 571 3rd ed. 2020 (listed mechanisms only); RP 572 5th ed. Nov 2023; RP 576 5th ed. Sep 2024; RP 577 3rd ed. Oct 2020 (Errata 1 Sep 2025); RP 578 4th ed. Feb 2023; ASME BPVC 2025 (V Arts 1, 2, 6, 7, 23 SE-797; VIII-1 U, UG, UW, UCS, App 1-4, 6, 8, 12; IX welding only); ASME PCC-2 2022 (listed articles) |
| Exam fee | Initial: 2026 $875 member / $1,125 non-member; 2027 $890 / $1,140. Late application $200. Reschedule (new window) $350 |
| Retakes | No published attempt limit or waiting period. Each application is valid 6 months from the first requested exam date; after it expires a new application and full fee are required. API does not disclose failed exam contents |
| Eligibility | Experience within the last 10 years with an authorized inspection agency: BS engineering/technology (or 3+ yrs military technical) = 1 yr inspection supervision/performance; 2-yr degree (or 2 yrs military) = 2 yrs pressure vessel design/fab/repair/operation/inspection incl. 1 yr inspection; high school = 3 yrs; no formal education = 5+ yrs |
| Renewal | Every 3 years: at least 20% of time on pressure vessel inspection in the last 3 years, 24 h CPD per cycle; 25-question open-book web quiz every 6 years |
What the exam covers
| I. Thickness measurements, inspection intervals and vessel integrity (calculations) | weight not published |
| II. Welding procedure and qualification evaluation (ASME IX, RP 577) | weight not published |
| III. Nondestructive examination (ASME V, VIII-1, API 510) | weight not published |
| IV. Practical knowledge - general | weight not published |
| V. Practical knowledge - specific (RP 571 listed mechanisms, RP 572, RP 576, RP 578, PCC-2 listed articles) | weight not published |
American Petroleum Institute lists these sections but publishes no weights, so treat them as equally important until you know otherwise.
Sources
Show the 5 official sources
- api.org/products-and-services/individual-certification-programs/schedule-exams (checked 2026-10-17)
- api.org/products-and-services/individual-certification-programs/certifications/api510 (checked 2026-10-17)
- api.org/products-and-services/individual-certification-programs/schedules-and-fees (checked 2026-10-17)
- api.org/products-and-services/individual-certification-programs/policies (checked 2026-10-17)
- api.org/-/media/files/certification/icp/overview/icp%20home/statistics/icpst_annual_meetin (checked 2026-10-17)
Facts checked 17 October 2026 against American Petroleum Institute's own documents (sources above). If something has changed, tell us and we will correct it within 2 business days.
Your next step
- 01Free API 510 check10 questions, untimed, about 23 minutes. Answers explained as you go.Start free
- 02Free sample lessonCorrosion rates, remaining life and inspection intervals: a full lesson from the course.Read the sample
- 03API 510 course$199. Lessons, timed practice exams and a plan around your exam date.See the plans
The API 510 course
Available now · instant accessLearn every Body of Knowledge section, work the calculations step by step, then prove it on timed exams.
- 8modules of lessonsEvery task on the outline
- 2full-length timed exams170 questions in 390 minutes each
- 401practice questionsEach one explained
- 6worked calculationsStep by step
- 1week-by-week study planSet to your exam date
Question bank and timed exams · Expert review in progress: questions marked Reviewed were checked by a pressure vessel inspection professional with 13 years in the industry (Oct 19, 2026). The newest questions are still being reviewed. Every answer key is confirmed by a separate blind solve, and reported errors are fixed within 2 business days.