The API 510 open-book part: on-screen PDFs, timing and a navigation drill

Much of the older advice online was written for a paper-based format with a different question count, so go by the current API documents linked below.

The format as API states it

The API 510 exam information page gives the current structure:

• 170 questions, 140 scored. The other 30 are pretest questions and aren't scored.
• 110 closed-book and 60 open-book questions.
• A 7.5-hour exam day: a short tutorial, 2.75 hours for the closed-book portion, a 45-minute lunch break, then 3.75 hours for the open-book portion.
• In person only, at designated Prometric test centers. Papers, notes and books are not allowed in Prometric's computer testing centers.

The exam tutorial states the same 170 questions and a 390-minute limit, with a scheduled 45-minute break after the closed-book section. The two documents agree: 2.75 hours plus 3.75 hours is 390 minutes of testing, and the lunch break and tutorial make up the rest of the 7.5-hour day. If you see "390 minutes" in one place and "7.5 hours" in another, that is why.

The math: the open-book part allows an average of 3.75 minutes per question (225 minutes for 60), against 1.5 minutes per question in the closed-book part (165 minutes for 110). The extra time exists because you are expected to look things up. It's still a short allowance once you include reading a long stem and working a calculation.

What the two parts test

The Body of Knowledge for this cycle (page 1) draws the line. The closed-book part covers knowledge and tasks that call for everyday working familiarity with API 510 and its references. The open-book part asks for more detailed information that an inspector would be expected to find in the documents but wouldn't normally commit to memory.

One BOK note matters for planning (page 2): the formulas and rules for corrosion rates, remaining life and inspection intervals may be closed-book. So don't count on looking up API 510 7.1, 7.2, 7.4 and Section 6 in the afternoon. Learn those methods well enough to work them without the book. Our API 510 calculations guide lists every calculation area in BOK Section I.A with the paragraph to open.

How the closed-book part locks

When you finish the closed-book section, you click Finish Section at the top right and confirm through a series of pop-ups. Once you submit, you can't go back to that section at any point, and any question left unanswered is marked incorrect. The break follows. You can end the break early, again after confirming, and the open-book section starts after it. The open-book section ends the same way: once it's submitted, the exam is finished and a general comment box follows.

What this means in practice:

• Use the Section Review grid (bottom left) before you submit. It filters by unattempted, attempted and flagged questions, and a pop-up warns you if flagged items remain.
• Leave no blanks. An unanswered question is scored as wrong, so a reasoned guess costs nothing.
• Don't park a closed-book question for the afternoon in the hope that the references will help. They won't be reachable for that section.

The tutorial describes the lock, and it applies to the API 510, 570 and 653 exams. For the morning itself, including what the Body of Knowledge says the 110 closed-book questions draw on and a way to drill recall, see our guide to the API 510 closed-book part.

Which documents appear on screen

The exam page says PDFs of the relevant codes and standards are on your computer during the open-book portion, in English, and that only the specific sections listed on the effectivity sheet are available. For the September 2026, January 2027 and May 2027 windows, the effectivity sheet lists:

The BOK adds that RP 572 is included with Annex B and the other annexes excluded (page 1). Our effectivity sheet guide covers the annex detail.

Go by the sheet. The sample screen in the tutorial, dated December 2023, shows an older API 510 edition and a shorter list of documents. It illustrates the viewer. What gets loaded is what the effectivity sheet for your window lists.

What the PDF viewer can and can't do

From the tutorial's "Using the PDF Viewer" screen:

• Opening a reference. Inside a question, a reference button opens the viewer. When the exam has more than one PDF, a library button at the top right lists them all.
• One PDF at a time. You can't place two documents side by side. A lookup that needs API 510 and then Section VIII means closing one and opening the other.
• Moving around. Page thumbnails, page-by-page and first/last buttons, a page number box, and bookmarks where the PDF has them. The sample screen shows a contents panel with section headings.
• Zoom and pan. Zoom in and out, plus preset views (automatic, actual size, fit page, full width).
• Highlight. You can highlight text in a reference and in the question stem, but not in the answer options.
• No Find. The tutorial states you won't have a Find (Ctrl F) function during the exam.

The same screen notes that some PDF functions vary by exam, so treat this list as the most you'll have. Other tools from the tutorial: a non-scientific on-screen calculator (a handheld can be requested from the proctor at an in-person center), a flag button, strike-out on answer options (right-click), a per-question comment box, and a timer that alerts you at 30, 15 and 5 minutes left. The timer keeps running during unscheduled breaks, while you write comments and if you reopen the tutorial.

A code-navigation drill you can run at home

Without Find, your speed depends on knowing where things are and on getting through a contents panel quickly. This drill builds that skill using your own authorized copies, which the effectivity sheet says to buy from API's listed redistributor. It uses no exam material and no code text.

Want a ready-made set first? The free API 510 lookup drill times you on five lookups at a pace you set.

Set up the conditions.

1. Open one reference PDF at a time. Close it before opening the next.
2. Turn off your reader's search, or agree with yourself never to press Ctrl F. Navigate only by bookmarks, the contents and page numbers.
3. Use a basic four-function calculator.

Write your prompts. Go through the BOK topic list and turn each line into a "where would I find this" prompt in your own words, tied to a section number you have to locate. Examples of the shape: "Find the paragraph that sets the pressure test temperature limits in Section VIII, Division 1." "Find the RP 571 mechanism that covers damage under insulation." "Find the PCC-2 article on fillet welded patches." Write 30 or more, mixed across all the documents, on cards or in a list you can shuffle.

Run timed rounds. Draw 12 prompts. For each, record the document, the section you landed on, whether it was right, and the seconds it took. Check each answer against the BOK or the document's own contents.

Read the log. An invented example of one round:

In this invented log the candidate cut the median lookup by about half (95 to 48 seconds) and the slowest document moved. That shift tells them where the next round's prompts should come from. Two kinds of miss need different fixes. A wrong document means you need a clearer map of which publication owns which topic. A right document but slow means you need to know its structure (part letters, article numbers, annex order) better.

Add the question. Once lookups are steady, pair each prompt with a small calculation using invented numbers, such as a static head or a part MAWP check, and time the whole thing. Keep the total under the 3.75-minute average with room to spare. Our static head calculator and MAWP and thickness calculator show each step, so you can check your arithmetic after a round.

Pacing the afternoon

A few habits that follow from the format:

• Take a first pass. Answer anything you can settle without the references, flag the rest, and come back. With 225 minutes for 60 questions, quick answers bank time for long lookups.
• Watch the section clock. The tutorial says Section Time Remaining is the clock that matters. Clicking it switches between time left in the section and time left across all content sections.
• Count document switches. Since only one PDF is open at a time, a question that crosses two documents costs two opens. Note the section numbers you need before you leave the first document.
• Don't spend the break. You can end the 45-minute break early, but it's the only scheduled pause, and the timer doesn't stop for unscheduled ones.

Before your window

Download the effectivity sheet for your window and check your copies against it edition by edition, including errata. Read the tutorial once at home so the screen layout isn't new on the day. Use the Body of Knowledge guide to build your prompt list, and see our free API 510 practice guide for what to use and what to leave alone.

Find your navigation gaps

The free 10-question check takes a few minutes, needs no signup and shows which topics need the most practice. The Long Seam course adds a lesson for each Body of Knowledge domain, timed practice exams and a study plan from your exam date.

FAQ

How many open-book questions are on the API 510 exam?

60 of the 170 questions, in 3.75 hours. That is an average of 3.75 minutes per question, against 1.5 minutes in the closed-book part.

Can you bring your own code books to the API 510 exam?

No. Papers, notes and books are not allowed in Prometric's computer testing centers. The references appear as PDFs on screen, limited to the sections on your window's effectivity sheet.

Can you search the PDFs in the API 510 open-book part?

No. The exam tutorial states you won't have a Find (Ctrl F) function, and only one PDF can be open at a time. Practice in your own copies by bookmarks, contents and page numbers with search turned off.

Can I look up the corrosion rate and remaining life formulas in the open-book part?

Don't count on it. The Body of Knowledge says the formulas and rules for corrosion rates, remaining life and inspection intervals may be closed-book, so learn them well enough to work without the book.

Sources

Show the list

• API 510 Pressure Vessel Inspector: exam information, American Petroleum Institute
• ICP Tutorial: API 510, API 570, API 653 (ICP-PD-201a, revised 28 Dec 2023), American Petroleum Institute, pages 1-20
• API 510 Exam Publications Effectivity Sheet, September 2026, January 2027 and May 2027, American Petroleum Institute
• API 510 Body of Knowledge, September 2026, January 2027 and May 2027, American Petroleum Institute, pages 1-2