API 510 exam guide: format, sections, fees and windows

The exam at a glance

• Questions: 170 in total. 140 are scored and 30 are pretest questions that you can't pick out.
• Parts: 110 closed-book questions, then 60 open-book questions, 390 minutes of testing in all. Both parts are taken on a computer.
• Closed book: no papers, notes or books. You get a calculator, scratch paper and a pencil. See the closed-book guide.
• Open book: PDFs of the publications on the Publications Effectivity Sheet appear on screen, and only the listed sections can be used. See the open-book guide.
• Where: in person at designated test centers. API 510 is not offered remotely.
• Blanks: unanswered questions are marked incorrect, so answer every one.

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 procedures and qualification records against ASME Section IX, with API RP 577 for welding inspection practice.
• III. Nondestructive examination: examination methods and acceptance requirements, drawing on ASME Section V, Section VIII Division 1 and API 510.
• IV. Practical knowledge, general: inspection planning, repairs, alterations, rerating and pressure testing under API 510.
• V. Practical knowledge, specific: the listed damage mechanisms from API RP 571 and the inspection practices in RP 572, RP 576 and RP 578, plus the listed PCC-2 repair articles.

API publishes topics, not percentage weights, so prepare all five. The Body of Knowledge guide goes through each section and the editions on the exam. Section I is the one most candidates find hardest to do fast, and the BOK says the corrosion rate, remaining life and interval methods may be closed-book, so practice them without the book. For the field side of those intervals, see what an API 510 inspection covers.

Fees, windows and eligibility

• Fees: API's 2027 fee table lists an initial exam fee of $890 for API members and $1,140 for non-members, and its 2026 table lists $875 and $1,125. A late application adds $200 and moving to a new window costs $350.
• Next windows: 7–28 May 2027 (apply by 4 March 2027), then 3–24 September 2027 (apply by 2 July 2027).
• Eligibility: experience within the last 10 years with an authorized inspection agency. The years needed depend on your education, from 1 year with a bachelor's degree in engineering or technology to 5 or more years with no formal education. The API 510 eligibility checker shows which route fits you.
• Total cost: the exam fee is one line of the budget. The exam cost calculator adds references, preparation and travel.

Fees and windows change, so confirm them on API's schedule and fees page, as read on 21 October 2026, before you apply. Every window, the Prometric change charges and the six-month application rule are in our API 510 exam schedule and fees guide. The education routes and a full cost worksheet are in the certification requirements and cost guide.

How to prepare

• Take the free check and start with whichever section scores lowest.
• Build a one-page method sheet for each calculation type and practice with fresh numbers until you don't need it. The API 510 calculations guide shows how to set them up.
• Practice open-book lookups only in the sections on your window's effectivity sheet. The effectivity sheet guide explains what it lists.
• Compare the three API inspector exams in API 510 vs 570 vs 653 if you are choosing which to sit first. The piping twin of this page is the API 570 exam guide.
• Weigh price, access, renewal and refund rules in API 510 prep options side by side.

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 section, timed practice exams and a study plan built from your exam date.

FAQ

How many questions are on the API 510 exam?

170 questions in 390 minutes of testing: 110 closed-book, then 60 open-book. 140 are scored and 30 are pretest questions you can't pick out, so treat every one as if it counts.

Is the API 510 exam open book?

Partly. The first 110 questions are closed-book, with only a calculator, scratch paper and a pencil. For the last 60, PDFs of the publications on the Publications Effectivity Sheet appear on screen, and only the listed sections can be used.

Can you take the API 510 exam online?

No. API 510 is offered in person only, at designated test centers. The next window is 7–28 May 2027, and you apply by 4 March 2027.

How much does the API 510 exam cost?

API's 2027 fee table lists an initial exam fee of $890 for API members and $1,140 for non-members, and its 2026 table lists $875 and $1,125. Late applications and window changes cost extra, and references, preparation and travel are separate.

Sources

Show the list

• API 510 Pressure Vessel Inspector, American Petroleum Institute
• ICP Schedules & Fees, American Petroleum Institute
• ICP exam tutorial (ICP-PD-201a), American Petroleum Institute
• API 510 Body of Knowledge, September 2026, American Petroleum Institute