The API 510 Body of Knowledge, explained section by section
The API 510 Body of Knowledge is the map to the exam. API publishes one for each exam window, together with a Publications Effectivity Sheet that lists the editions and the sections you can use in the open-book part. Know both for your window and you know what you are studying for. For the format, fees and windows around it, see the API 510 exam guide.
- Questions
- 170
- Time
- 390 minutes
- Exam fee (paid to API, not us)
- $875–$890 member / $1,125–$1,140 non-member
- 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. Our WPS and PQR review guide sets out the section's limits and a step order, with an invented worked review.
- 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. The damage mechanisms guide lists the 15 RP 571 paragraphs on the current sheet, with where each tends to show and how it is commonly found, and the damage mechanism quiz drills naming each one from its service conditions.
API doesn't publish weights for these sections. For practice setting up the exam's calculations, see the API 510 calculations guide.
Try one question
Question 1 of the free 10-question check on API 510. No signup. Then ask Patch, the AI study assistant, why the answer is right and the others are wrong.
IV. Practical knowledge - general
Which hydrotest situation carries the highest brittle fracture risk?
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How to prepare
- Take the free 10-question check 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. For minimum thickness and MAWP, the MAWP and thickness calculator lets you check your working. For hydrostatic and pneumatic test pressure, the hydrotest pressure calculator does the same.
- Practice open-book lookups in the sections on the effectivity sheet, because those are the ones on screen on exam day.
- The BOK names the corrosion rate, remaining life and interval methods as possibly closed-book, so learn them without the book. Our closed-book guide shows how to turn each BOK line into a recall prompt.
- Apply before the window's deadline. An application is valid for 6 months from your first requested exam date.
For the hands-on side of sections IV and V (practical knowledge), our pressure vessel inspection checklist walks external, internal and on-stream inspection with the records to pull and where damage tends to form.
Find your weak sections in minutes
The free 10-question check is spread across the Body of Knowledge, needs no signup and explains every answer as you go. You finish knowing which section to open first. The Long Seam course then gives you a lesson for each domain, timed practice exams and a study plan built from your exam date.
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- 8modules of lessonsEvery task on the outline
- 2full-length timed exams170 questions in 390 minutes each
- 617practice questionsEach one explained
- 6worked calculationsStep by step
- 1week-by-week study planSet to your exam date
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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 (paid to API, not us) | $875–$890 member / $1,125–$1,140 non-member |
| 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 |
Fee details
Initial: 2026 $875 member / $1,125 non-member; 2027 $890 / $1,140. Late application $200. Reschedule (new window) $350
What the exam covers
| I. Thickness measurements, inspection intervals and vessel integrity (calculations) | not published by American Petroleum Institute |
| II. Welding procedure and qualification evaluation (ASME IX, RP 577) | not published by American Petroleum Institute |
| III. Nondestructive examination (ASME V, VIII-1, API 510) | not published by American Petroleum Institute |
| IV. Practical knowledge - general | not published by American Petroleum Institute |
| V. Practical knowledge - specific (RP 571 listed mechanisms, RP 572, RP 576, RP 578, PCC-2 listed articles) | not published by American Petroleum Institute |
American Petroleum Institute lists these sections but publishes no weights, so treat them as equally important until you know otherwise.
Sources
Show the 5 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 come from American Petroleum Institute's own documents (sources above); the latest source retrieval was . If something has changed, tell us and we will correct it within 2 business days.
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From the blog
- API 510 Pressure Testing and Impact Testing: What to Know
- ASME PCC-2 on the API 510 Exam: The 14 Articles to Study
- NDE on the API 510 Exam: What Section V Covers