by thinQtankLearning.com
Home › Oil & Gas › API 510
American Petroleum Institute (API) Individual Certification Programs

API 510 Pressure Vessel Inspector Certification

The credential for inspectors who keep in-service pressure vessels safe — thickness, corrosion rates, repairs, rerates and fitness for service.

Enroll free and start Sign in

Also inspecting piping? API 570 Piping Inspector → · Tanks too? API 653 Storage Tank Inspector →

Questions170 multiple-choice (140 scored, 30 unscored pretest)
Time7.5-hour day: 2 h 45 min closed-book (110 questions), 45-min lunch, 3 h 45 min open-book (60 questions)
Open book?No books in the room — the second section shows the in-scope codes as on-screen PDFs
WhereIn person at a Prometric test center, inside one of three 3-week windows a year
Fee$875 API members · $1,125 non-members
Who sits itEngineering degree + 1 year, 2-year degree + 2 years, high school + 3 years, or 5 years of vessel experience — each with at least 1 year of inspection, within the last 10 years
PassingScaled score 400 on a 200–500 scale; Prometric emails results within 24 hours

About the exam

API 510 certifies inspectors of in-service pressure vessels in refineries, chemical plants and other process facilities. It shows you can measure and evaluate metal loss, set inspection intervals, recognize damage mechanisms, judge welding and NDE, and control repairs, alterations and rerating under API 510 and ASME Section VIII, Division 1.

The exam has a closed-book section that tests everyday working knowledge — inspection practices, damage mechanisms, relief devices, welding and NDE principles — and an open-book section where the codes appear on screen and you work calculations: corrosion rates and remaining life, required thickness and MAWP of shells and heads, static head, joint efficiency, test pressures, impact-test exemption and attachment weld sizes.

Our practice follows API's effectivity sheet for the September 2026 to May 2027 exams: API 510 11th edition (2022, with errata), API RP 571 3rd edition (15 named damage mechanisms), RP 572 5th edition (2023), RP 576 5th edition (2024), RP 577 3rd edition (2020), RP 578 4th edition (2023), the 2025 ASME Boiler and Pressure Vessel Code (Sections V, VIII Division 1 and IX) and ASME PCC-2 2022.

How we track your progress

Every blueprint domain moves through five levels as you study:

  1. Not startedNo questions answered in this domain yet.
  2. Getting startedFirst questions answered — not enough yet to judge.
  3. DevelopingAt least 5 answered and 50% or better on your recent questions.
  4. ProficientAt least 15 answered and 70% or better on your recent questions.
  5. Exam readyAt least 25 answered, 80% or better recently, and holding up on hard questions.

The exam blueprint

API 510 Body of Knowledge and Publications Effectivity Sheet for the September 2026, January 2027 and May 2027 exams — 170 items (140 scored, 30 pretest): 110 closed-book, 60 open-book across 8 Body of Knowledge areas; weights are QuizMe estimates. Tap a domain to see its topics.

1 Inspection practices, intervals and records about 18% (est.) of the exam
Owner-user, inspector and engineer roles and responsibilitiesInspection plans and risk-based inspectionInternal, external and on-stream inspectionInterval setting: half remaining life, 10-year cap and RBIThickness monitoring locations and methods (API 572)Corrosion under insulation and external inspectionInspection safety and vessel preparationInspection records, reports and recommendationsDeferral of inspection and repair recommendations

60 practice questions in this domain so far

2 Corrosion and code calculations about 18% (est.) of the exam
Long-term and short-term corrosion ratesRemaining corrosion allowance and remaining lifeNext inspection date from corrosion dataJoint efficiency from weld category and RT markingRequired thickness of cylindrical and spherical shells (UG-27)Ellipsoidal and hemispherical heads (UG-32)MAWP of a corroded shell or headStatic head and part MAWP vs vessel MAWPCorrosion allowance: adding and removing it correctly

60 practice questions in this domain so far

3 Damage mechanisms (API 571) about 12% (est.) of the exam
Brittle fractureCorrosion under insulation and atmospheric corrosionWet H2S damage: blistering, HIC, SOHIC and SSCAmine, caustic and chloride stress corrosion crackingHigh-temperature hydrogen attack and H2/H2S corrosionSulfidation and naphthenic acid corrosionHydrochloric acid and caustic corrosionErosion, erosion-corrosion and boiler condensate corrosion

40 practice questions in this domain so far

4 Welding: ASME IX and API 577 about 14% (est.) of the exam
WPS and PQR review: essential and nonessential variablesWelder performance qualification (WPQ) and limitsMechanical tests: tension, bend and acceptanceP-numbers, F-numbers and A-numbersWelding processes: SMAW, GTAW, GMAW and SAWWeld defects, discontinuities and causesPreheat, PWHT and alternatives to PWHTWelding metallurgy and hardnessWeld joint types, sizes and attachment welds

48 practice questions in this domain so far

5 NDE (ASME V) and material verification (API 578) about 11% (est.) of the exam
Radiography: IQIs, density, markers and backscatterLiquid penetrant examinationMagnetic particle examination: yoke and prodUltrasonic thickness measurement (SE-797)Section V general requirements and recordsNDE selection for surface vs volumetric flawsPositive material identification programs

36 practice questions in this domain so far

6 Pressure-relieving devices (API 576) about 7% (est.) of the exam
Relief valve, safety valve and rupture disk typesSet pressure, overpressure and blowdown termsCauses of improper device performanceInspection and testing intervals for relief devicesShop inspection, bench testing and recordsInstallation checks: block valves and discharge piping

24 practice questions in this domain so far

7 Repairs, alterations, rerating and pressure testing about 12% (est.) of the exam
Repair vs alteration: definitions and authorizationRerating requirements and nameplate changesTemporary repairs, fillet-welded patches and insert platesWeld buildup, overlay and flaw excavation (PCC-2)Hydrostatic test pressure and temperature correctionPneumatic testing precautionsNDE in lieu of pressure testingHot taps and in-service welding

40 practice questions in this domain so far

8 ASME VIII Div. 1 design and fabrication basics about 9% (est.) of the exam
Scope, nameplate stamping and data reportsWeld joint categories and radiography requirementsImpact testing and MDMT exemption conceptsOpenings and reinforcement conceptsWeld sizes at nozzle attachments (UW-16)Postweld heat treatment requirements for carbon steelExternal pressure concepts

32 practice questions in this domain so far

What you get when you access this exam

Free with your QuizMe account.

Inspector scenarios aligned to the Body of Knowledge

Every question is tagged to one of the 8 API 510 areas and its topics — corrosion math, shell thickness, damage mechanisms, WPS/PQR review and what the inspector does next.

Exam-critical hints

Reveal the code concept that unlocks the question — the formula, the governing rule, the value that matters. Every answer comes with the full rationale and worked solution.

Adaptive testing

Questions steer toward your weakest areas, weighted by our estimate of how much each counts on the real exam, and get harder as you get stronger.

Timed practice exams

Full-length exams at the real pace — 170 questions in 6.5 hours of testing — with a live pacing indicator and a full review.

Flashcards, case simulations and guides

100 flashcards for damage mechanisms, code definitions and formulas, 6 inspection cases where a vessel's thickness data, damage and repair decisions unfold step by step, and interactive illustrated guides you explore hotspot by hotspot.

Progress for every blueprint area

Each area moves from Not started to Getting started, Developing, Proficient and Exam ready — so you know exactly what to study next.

Test at home or at a center

Apply through API's ICP portal by the deadline for your chosen window. Once approved, you get an authorization to schedule your API 510 exam with Prometric on any open day inside that window. The next windows are January 2–22, 2027 (apply by October 29, 2026) and May 7–28, 2027 (apply by March 4, 2027).

At a Prometric test center

  • API 510 is offered in person only — API stopped remote testing for 510, 570, 653 and 1169 in September 2024.
  • Bring government-issued photo ID; the name must match your API account exactly.
  • No papers or code books in the room. A calculator, scratch paper and pencil are provided, and an on-screen calculator is built in.
  • Phones, watches, bags and notes go in a locker.

Before you book

  • Your application is valid for 12 months from the first window you request; moving to a different window means a new application and fees.
  • Prometric rescheduling inside a window: free 60+ days out, $35 at 30–60 days, $70 at 5–29 days, not allowed under 5 days.
  • Buy or borrow the exact code editions on the effectivity sheet and study from them — the exam shows those PDFs, not your copies.
  • Work through API's exam tutorial so the on-screen PDF viewer isn't new on exam day.

Exam-day game plan

How to walk in ready — and how to pace 170 questions in 6.5 hours.

Pacing checkpoints

Hit these and you finish with time to revisit your flagged questions. Our timed practice exams run at this same pace.

55questions1:23
110questions2:45
140questions4:38
170questions6:30

The week before

  • Take one full-length timed practice exam 3–5 days out, then rest.
  • Spend your last sessions on the heaviest areas — calculations and inspection practices — plus anything still below Proficient.
  • Rework every calculation type in the Body of Knowledge from a blank page, in both US customary and SI units.
  • Practise finding paragraphs in the effectivity-sheet editions using bookmarks and the table of contents, not memory.

Exam morning

  • Eat a real breakfast; the day runs about 7.5 hours with one 45-minute lunch break.
  • Arrive 30 minutes early at the Prometric center with ID that matches your API account.
  • Use the restroom right before you start.

During the exam

  • The first section is closed-book: 110 questions in 2 hours 45 minutes. Answer everything before you click Finish — you can't come back.
  • After the break, the open-book section shows the codes on screen: 60 questions in 3 hours 45 minutes, so there's time to look things up.
  • Look up only what you need. Write down every given value, the formula and the units before you calculate.
  • Corroded condition matters: use the corroded radius and remove the corrosion allowance before you calculate thickness or MAWP.
  • Answer every question — there's no penalty for guessing, and multiple-select items need every correct choice.
  • 30 questions are unscored pretest items you can't identify.

Keep your head

  • A few nerves sharpen focus. If you freeze, take three slow breaths and reread the stem.
  • You're measured against a fixed standard, not other test-takers.
  • Change an answer only when you find a real reason in the stem or the code.

Keeping your API 510 certification

  • Certification lasts 3 years.
  • To recertify, show that at least 20% of your time over the 3 years was spent performing or supervising in-service pressure vessel inspection.
  • You also need 24 continuing professional development (CPD) hours per 3-year cycle, across at least two CPD categories.
  • Every 6 years — every second recertification — you also pass API's online open-book quiz: 25 questions in 4 hours, two attempts. Fail twice and you must retake the full exam.
  • Apply from 90 days before your expiration date; a 90-day late window carries extra fees.

Official sources and further reading

Ready to start?

340 questions and scenarios across the blueprint — and growing.

Enroll free

API 510, API 570, API 653 and API 1169 are certification programs of the American Petroleum Institute. QuizMe and thinQtank Learning are not affiliated with or endorsed by API, ASME or Prometric. API and ASME codes and standards are copyrighted — candidates need their own copies of the editions on API's effectivity sheet, and our practice items are original, not recalled exam questions. Exam details are summarized from API's published Body of Knowledge, effectivity sheet and program pages; fees, dates and editions change — always confirm at api.org before you apply. Our domain weights are estimates; API publishes no percentages.