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For inspectors taking an API exam

API 510, 570, 653 and 571 inspector exam prep, free to start

Know the method closed book. Find it fast open book.

API 510, API 570, API 653, API 571 and API 510 recert practice questions. Every answer is explained and your weakest domain is named. Start with the free 10-question check.

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Full courses from $149, with lessons, timed practice exams and a study plan. See the courses →

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  • Score by domain
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API 510 free checkExample report
I. Thickness measurements, inspection intervals and vessel integrity (calculations)78%
II. Welding procedure and qualification evaluation (ASME IX, RP 577)52%
III. Nondestructive examination (ASME V, VIII-1, API 510)66%
IV. Practical knowledge - general40%
Study first: IV. Practical knowledge - general

Illustration of the breakdown you get at the end. These are not real scores.

Pick your exam

One free check for each exam

Original practice questions written to American Petroleum Institute's published outline. Every answer comes with a full explanation.

Each check is weighted to that exam's published content outline, so your score breakdown matches what you will be tested on. Each card has its exam's full course and price: lessons, timed exams and a study plan, with Patch, your AI study assistant, built in.

  • Exam 1 of 5Available now · instant access

    API 510

    API 510 Pressure Vessel Inspector

    Questions
    170
    Time
    390 min
    Exam fee (paid to API, not us)
    $875–$890 member / $1,125–$1,140 non-member
    Free 10-question check10 questions, untimed, about 23 minutes

    The full course$199

    Learn every Body of Knowledge section, work the calculations step by step, then prove it on timed exams.

    8 modules of lessons2 full-length timed exams617 practice questions

    Also in API 510: Week-by-week plan to your exam date, Flashcards from your misses, Timed code lookups, Exam-week mode

    See the course for API 510 Exam guide
    Get the API 510 course · $199

    Terms and refunds · Secure checkout by Stripe

  • Exam 2 of 5Available now · instant access

    API 570

    API 570 Piping Inspector

    Questions
    170
    Time
    390 min
    Exam fee (paid to API, not us)
    See the guide
    Free 10-question check10 questions, untimed, about 23 minutes

    The full course$199

    Learn every Body of Knowledge section, work the calculations step by step, then prove it on timed exams.

    8 modules of lessons2 full-length timed exams660 practice questions

    Also in API 570: Week-by-week plan to your exam date, Flashcards from your misses, Timed code lookups, Exam-week mode

    See the course for API 570 Exam guide
    Get the API 570 course · $199

    Terms and refunds · Secure checkout by Stripe

  • Exam 3 of 5Available now · instant access

    API 510 recert

    API 510 Six-Year Recertification Web Quiz

    Questions
    25
    Time
    240 min
    Exam fee (paid to API, not us)
    See the guide
    Free 10-question check10 questions, untimed, about 30 minutes

    The full practice pack$59

    Refresh the rules and the RP 571 sections the six-year web quiz draws on, with two timed 25-question practice forms.

    2 full-length timed exams174 practice questions

    Also in API 510 recert: Practice on your slowest questions

    See the practice pack for API 510 recert Exam guide
    Get the API 510 recert practice pack · $59

    Terms and refunds · Secure checkout by Stripe

  • Exam 4 of 5Available now · instant access

    API 653

    API 653 Aboveground Storage Tank Inspector

    Questions
    170
    Time
    390 min
    Exam fee (paid to API, not us)
    See the guide
    Free 10-question check10 questions, untimed, about 23 minutes

    The full course$199

    Learn every Body of Knowledge section, work the tank calculations step by step, then prove it on timed exams.

    8 modules of lessons2 full-length timed exams347 practice questions

    Also in API 653: Week-by-week plan to your exam date, Flashcards from your misses, Code-book section drills, Exam-week mode

    See the course for API 653 Exam guide
    Get the API 653 course · $199

    Terms and refunds · Secure checkout by Stripe

  • Exam 5 of 5Available now · instant access

    API 571

    API 571 Corrosion and Materials

    Questions
    110
    Time
    195 min
    Exam fee (paid to API, not us)
    See the guide
    Free 10-question check10 questions, untimed, about 18 minutes

    The full course$149

    Learn each family of damage mechanisms, then prove it on closed-book timed exams.

    6 modules of lessons2 full-length timed exams249 practice questions

    Also in API 571: Week-by-week plan to your exam date, Flashcards from your misses, Exam-week mode

    See the course for API 571 Exam guide
    Get the API 571 course · $149

    Terms and refunds · Secure checkout by Stripe

Every course includes

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More free practice

The Long Seam app

Study for the API 510, API 570, API 510 recert, API 653 and API 571 exams anywhere you are

The Long Seam app for iPhone and Android is built around your study buddy, with quick practice questions and your study plan. Long Seam already works in your phone's browser today.

  • Today's questions, aimed at your weakest domain
  • Your week's plan, counting down to exam day
  • The same original questions and explanations as the site
  • Every exam on the site: API 510, API 570, API 510 recert, API 653 and API 571
  • Patch (AI), your Long Seam study buddy, explains why the answer is right and the others are not: 3 free asks, 10 more with your email

Patch AI, your Long Seam study buddy, is at the center of the app.

  • Tutor walkthroughs: Step-by-step help on any question you answered, at your pace.
  • My study plan: A day-by-day plan built from your weakest domains.
  • Weak-spot quiz: Quiz yourself on what you missed, with spaced review so it sticks.
Get notified when it's ready

API 510 certification from the American Petroleum Institute's Individual Certification Programs qualifies you as an authorized pressure vessel inspector. The exam is long and code-heavy, and it rewards inspectors who know their methods and can find things fast. On the open-book part you don't need to know the answer cold, you need to find it. It runs for 390 minutes with a closed-book part and an open-book part, and the open-book part gives you only the code sections listed on that window's Publications Effectivity Sheet.

Start with the free 10-question check

Find out where you stand in a few 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 with a score by domain and a clear first topic to study.

Working on piping instead? The free API 570 practice test gives you 10 original questions on piping inspection and calculations, explained as you answer, with no signup. For worked examples first, the API 570 practice test guide walks through three explained questions and how the exam is set up. Planning the application? See the API 570 certification guide for eligibility, fees and deadlines.

Already certified and facing the six-year recertification quiz? The free API 510 recert check refreshes intervals, repairs, records and the RP 571 sections the quiz can reach.

Closed-book and open-book parts

  • Closed book: 110 questions. You have no code books, only the calculator and scratch paper the test center provides.
  • Open book: 60 questions. You use only the sections listed on the Publications Effectivity Sheet for your window.
  • Total: 170 questions, 140 of them scored, in 390 minutes of testing.

Calculations decide a lot of results

The first section of the Body of Knowledge covers thickness measurements, inspection intervals and vessel integrity: corrosion rates, remaining life, inspection intervals, minimum required thickness, static head and MAWP. These calculations follow set methods, and getting the method right is most of the work. API doesn't publish section weights, so prepare every section of the Body of Knowledge. Our calculations guide walks through each area with worked examples.

The exam in brief

  • Format: 170 questions (140 scored), with 110 closed-book and 60 open-book. Calculator and scratch paper are provided.
  • Where you test: in person at Prometric test centers during set windows. API 510 is not offered remotely.
  • Fees: API's 2027 fee table lists $890 for members and $1,140 for non-members, and its 2026 table lists $875 and $1,125. Every API 510 window still taking applications tests in 2027. An application is valid for 6 months from your first requested exam date, and after that it's a new application and the full fee again.
  • Experience: required before you can sit, and it depends on your education. See the requirements and cost guide, or run your dates through the API 510 eligibility checker.

Read the Body of Knowledge guide for the five sections and how to prepare for each.

How to use Long Seam

  1. Start with the free 10-question check at the top of this page to see your score by domain.
  2. Work the calculation types until you can set each one up without looking anything up.
  3. Read the effectivity sheet for your window and practice finding those sections fast.

The Long Seam course gives you a lesson for each Body of Knowledge domain, timed practice exams and a study plan built from your exam date. After each timed exam you see your score change by domain since the last one. Timed lookup sets train the open-book part: 8 lookups per set in your own copy of API 510 (or ASME B31.3 for API 570), answered as section, paragraph or table numbers, with your median seconds and how it moved since the last set. Code sections are cited by number only.

Also on Long Seam

Guides and tools

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Exam facts and requirements

39 resources

What is on the exam, who can sit it, what it costs and how to keep it.

All 39 in exam facts and requirements →

Study guides

7 resources

Work through one topic at a time, with the method and worked examples.

All 7 in study guides →

Practice tests and drills

5 resources

Check yourself on questions, symbols and code look-ups, then see what to fix.

All 5 in practice tests and drills →

Tools and calculators

13 resources

Run the math your exam asks for and get the answer in seconds.

All 13 in tools and calculators →

Updated 13 November 2026.