API 510 practice exam: free questions and what to avoid

What API gives you for free

API's exam page links no practice exam or sample question set. What API does publish free is the material that defines the exam, and that is worth more than any question bank because everything else is built from it.

The exam tutorial. The API 510 exam information page recommends viewing the ICP exam tutorial before exam day. It's a 22-page PDF covering the API 510, 570 and 653 exams. It walks through the testing screen, and it includes practice items for each question format, written on general topics rather than inspection content. That makes it practice for the interface, not the subject. The formats it shows:

• Multiple choice with one correct answer.
• Multiple response, marked with a line telling you more than one answer may be correct.
• Drag and drop, where options go into one or more answer boxes.
• Extended matching, where you connect items in two columns.

The tutorial states that drag-and-drop and extended matching items get no partial credit. One wrong placement or match makes the whole item wrong. If your only practice has been four-option multiple choice, the other three formats are worth a look before the day. The tutorial also covers the flag, strike-out, highlight, comment and section review tools, and the PDF viewer used in the open-book part. Our open-book guide goes through the viewer in detail, including the missing Find function.

The Body of Knowledge. The Body of Knowledge for September 2026, January 2027 and May 2027 lists the topics questions are drawn from. Section I.A lists the calculations by name with the paragraph numbers to open. That list is the best free practice plan available, because it tells you exactly what you must be able to calculate. Our Body of Knowledge guide explains each section.

The effectivity sheet. The same exam page links the effectivity sheet for your window, which names the editions and the sections that will be on screen in the open-book part. The BOK itself notes that the exam is based on the editions on that sheet, even where a workplace or jurisdiction uses a different edition. Any practice material written to an older edition can teach you the wrong paragraph number.

The pretest policy. API's pretest questions policy explains that some items on every form are unscored, that candidates can't tell which ones, and that passing scores are set by equating rather than on a curve. The exam page gives the split for API 510: 170 questions, 140 scored. Treat every item on the day as if it counts.

What we offer free

Everything below is original. None of it is a real or recalled exam item, and code sections are cited by number only.

• The free 10-question check. Ten original items across the Body of Knowledge, explained as you answer, with a score broken down by BOK area. No signup. It shows you where to start.
• Calculators that show their steps. The corrosion rate calculator, remaining life calculator, static head calculator, MAWP and thickness calculator and hydrotest pressure calculator. Use them to check hand work, not to replace it. For the RP 571 side, the damage mechanism quiz has you name the mechanism from the service conditions. The tutorial describes the exam's on-screen calculator as non-scientific, and says a handheld one can be requested from the proctor at an in-person center.
• The API 510 calculations guide. Every calculation area in BOK Section I.A, with the inputs each one needs, the paragraph to open and worked examples using invented numbers.
• A free sample lesson, a question of the day and free API 510 flashcards, all original. Cards you miss come back sooner.
• The free API 570 practice test. The same 10-question check for piping inspectors, with calculations explained as you answer. The free API 570 flashcards cover the terms.
• The free API 510 recert check. For certified inspectors facing the six-year recertification quiz: intervals, repairs, records and the RP 571 sections it can reach.

3 sample questions

Original practice items with invented numbers. Open your own copies of the sections named.

1. Remaining life. A vessel shell has a measured thickness of 0.412 in. and a required thickness of 0.350 in. The corrosion rate is 0.006 in. per year. What is the remaining life?

• A. 5.2 years
• B. 68.7 years
• C. 10.3 years
• D. 58.3 years

Answer: C. Remaining life is (actual minus required thickness) divided by the corrosion rate: 0.062 / 0.006 = 10.3 years, following API 510 section 7.1. B divides the full measured thickness, D divides the required thickness, and A halves the answer, which confuses remaining life with an inspection interval.

2. Hydrotest pressure. A vessel built to ASME VIII-1 has a MAWP of 250 psi, and the lowest stress ratio for its parts is 1.0. What standard hydrostatic test pressure applies?

• A. 325 psi
• B. 250 psi
• C. 375 psi
• D. 275 psi

Answer: A. The standard hydrostatic test in ASME VIII-1 UG-99 uses 1.3 times MAWP times the lowest stress ratio: 1.3 × 250 × 1.0 = 325 psi. B is the MAWP itself, C uses the 1.5 factor from older editions, and D is an unsupported 1.1.

3. Repairs. An owner plans a weld repair on the pressure boundary of a vessel in service. Who must authorize the work before it starts?

• A. The welding foreman
• B. The unit operator
• C. The purchasing agent
• D. The authorized inspector

Answer: D. API 510 Section 8 (repairs and alterations) requires inspector authorization before repair or alteration work begins. The others may be involved in the job, but none of them holds that authority.

Check item 1 in the remaining life calculator and item 2 in the hydrotest pressure calculator.

What to avoid, and why

Recalled-question PDFs

Files sold or shared as real test items, recalled question lists and answer-key PDFs are the main thing to avoid. We don't link to them, and we'd ask you not to use them.

The reason is in API's own rules. The Code of Conduct on API's ICP Certification Applications page says candidates agree to refrain from any reproduction or disclosure of API exam content. The same page says API may deny applications or terminate certifications for a violation of the Code of Conduct or the Legal Agreement. The ICP Policies page adds that API can cancel a candidate's exam results and deny certification if it learns of prohibited activity, and that API won't disclose or return the contents of a failed exam to anyone. A file presented as real exam content is either a breach of those terms by whoever made it, or not real. Neither is something to build your preparation on.

There are practical reasons too:

• Editions move. The effectivity sheet changes between windows. A recalled item written against an earlier edition can point to a paragraph that has been renumbered or changed. Even API's own tutorial, dated December 2023, shows an older API 510 edition in its sample PDF viewer, so an older document is easy to come across without noticing.
• No explanations. A list of keys teaches you to recognize an answer, not to find it. The open-book part rewards knowing where things are in the code, and the calculation areas reward method.
• No checking. A shared answer key gives you no way to tell whether anyone checked it, and a wrong key gets copied along with the rest.

Rehosted code books

Free "API 510 PDF" or "ASME VIII PDF" downloads are copies of copyrighted publications. The Policies page says the study materials listed on each effectivity sheet can be bought from API's publications store. Use your own authorized copies, which also means you practice on the same editions that will be on screen.

Practice sets that drill out-of-scope topics

Page 4 of the BOK lists 22 engineering topics candidates are not expected to know, such as external pressure calculations, flange calculations and relief valve sizing. A free question set heavy on those is spending your time outside the published scope.

Claims of API backing

The Policies page states that API does not endorse test preparation classes, courses or companies. That includes us. Be wary of any free test that claims API approval.

A practice routine using only free tools

This routine assumes you have your own copies of the references on the effectivity sheet. It uses no exam material, and after the first week it repeats on a weekly cycle.

Week 1: find your starting point.

1. Read the tutorial once, start to finish, and try each practice screen.
2. Take the free 10-question check. Note your weakest BOK area and every item where you knew the topic but not the paragraph.
3. Print BOK Section I.A and tick each calculation area you can already work without notes. The API 510 formula sheet lists the methods to check yourself against.

Each week after: one calculation block, one navigation block, one review block.

Calculation block. Pick one unticked BOK area. Write your own practice problem with invented numbers, work it by hand with a four-function calculator, then check it with the matching calculator. Do it in US units, then convert and redo it in SI, since the BOK expects both. Corrosion rate and interval methods deserve extra time: the BOK says those formulas and interval rules may be tested closed-book.

An example of the kind of problem to write yourself, with invented numbers: a vertical vessel is full of liquid at specific gravity 1.0 (the value the BOK says all static head problems use). A nozzle sits 22 ft below the point where MAWP is stated. Using the BOK's 0.433 psi/ft factor, the static head at the nozzle is 22 × 0.433 = 9.53 psi. At an invented MAWP of 180 psi, the total pressure at the nozzle is 180 + 9.53 = 189.53 psi. Then check it in the static head calculator, and look up the difference between vessel MAWP and part MAWP in UG-98 in your own copy.

Navigation block. Write ten "where would I find this" prompts from the BOK topic list in your own words, then find each one in your copies with search turned off, one PDF at a time, timing each lookup. The open-book guide has the full drill and a sample log. For five ready-made prompts on a clock, try the free API 510 lookup drill.

Review block. Go back to any item you missed in the free check or the question of the day. For each, write one line on why the right answer is right, with the section number. If you can't name the section, that's a navigation gap, not a knowledge gap, and it goes into next week's prompts.

Every few weeks: retake the free check and compare your domain breakdown with the first attempt. A change in the weakest area tells you where to move next. Use the score as a study signal for what to work on next.

Before your window

Download the effectivity sheet and BOK for your window again in case API has revised them, and check your references edition by edition. Then work through the calculations guide area by area.

Start now

Take the free 10-question check for API 510. It takes a few minutes and needs no signup. You get a score by Body of Knowledge domain and an explanation for every answer. The Long Seam course picks up where it leaves off, with a lesson for each domain, timed practice exams and a study plan built from your exam date.

FAQ

Does API publish a free API 510 practice exam?

No. API's exam page links no practice exam or sample question set. It does publish the exam tutorial, the Body of Knowledge and the effectivity sheet for free, and the tutorial has practice items for each question format on general topics.

What can I practice for free on Long Seam?

The free 10-question check, the three sample questions above, a free sample lesson, a question of the day and calculators that show their steps. All of it is original, with code sections cited by number only.

Should I use recalled API 510 question PDFs?

No. API's Code of Conduct says candidates agree to refrain from any reproduction or disclosure of exam content, and API can cancel results or certifications for prohibited activity. Recalled items can also point to paragraphs that have changed between editions.

Does API endorse any API 510 prep course?

No. API's Policies page states that API does not endorse test preparation classes, courses or companies. That includes us.

Sources

Show the list

• API 510 Pressure Vessel Inspector: exam information, American Petroleum Institute
• ICP Policies, American Petroleum Institute
• ICP Tutorial: API 510, API 570, API 653 (ICP-PD-201a, revised 28 Dec 2023), American Petroleum Institute, pages 1-22
• API 510 Body of Knowledge, September 2026, January 2027 and May 2027, American Petroleum Institute, pages 1-4