API 570 vs API 510: Which Exam Should You Take First?

What is the same

API's certification pages for 510 and 570 publish the same structure, so you are not choosing between a harder and an easier format:

• A 7.5-hour exam day at a Prometric center.
• 170 questions, 140 scored, with 110 closed-book and 60 open-book.
• A three-year certification with a 20% work requirement, 24 hours of continuing professional development and a web quiz every six years.
• The same four education routes and the same fee row, which for 2027 initial certification is $890 for members and $1,140 for non-members.

Our three-way comparison sets these side by side with API's own wording. That also means the exam skills transfer: calculation speed, code navigation and welding procedure review work the same way on both. Our API 510 study plan and API 570 study plan use that overlap.

What is different

The equipment and the reference stack change.

• Calculations. The 510 Body of Knowledge works from ASME Section VIII, Division 1 for vessels. The 570 one works from B31.3 and B16.5 for piping, with flange ratings, weld joint factors and thermal expansion.
• Publications. Both draw on RP 571, 577 and 578 and on RP 576 for relief devices. API 510 adds RP 572 for vessel inspection. API 570 adds RP 574 for piping components and ASME PCC-2. Each program lists a different set of RP 571 paragraphs, so do not assume your notes carry over line for line.
• Experience. API needs your experience tied to the equipment of the certification you apply for. Time on vessels counts for 510. Time on in-service piping counts for 570.

Read the API 570 Body of Knowledge article for the piping outline and the API 510 Body of Knowledge guide for the vessel one.

Four questions that pick the exam

1. What does your employer need signed? If your site needs an authorized piping inspector, 570 has a job attached. If it needs a vessel inspector, so does 510. Ask your supervisor which gap hurts more.
2. Where do your last 10 years of experience sit? API's pages say the experience must come within the last 10 years while employed by or contracted to an authorized inspection agency. Sort each period of work by equipment, then check your education route against the minimum years. The API 510 requirements and cost guide and the API 570 requirements, cost and schedule guide walk through building that record.
3. Which application deadline can you meet? A missed deadline can cost you a window and a $200 late fee.
4. Which reference books do you already own? Vessels people often have Section VIII and RP 572. Piping people often have B31.3 and RP 574. Starting with the stack you know shortens your first plan.

A worked example with invented dates

Dana inspects vessels and piping for a refinery contractor. Over the last 5 years, about 3 were on vessels and 2 on piping. Both routes are open. Dana's employer needs a vessel signatory by spring.

• Choice: 510 first, in the 7 to 28 May 2027 window (application deadline 4 March 2027 per API's schedule page).
• Why: it matches the job, the application deadline is far enough away for a proper plan and the 510 references are already on the shelf.
• Second exam: 570 in the 8 to 29 October 2027 window (application deadline 5 August 2027), with the same study habits and new reading on B31.3, B16.5 and RP 574.

Notice what Dana did not do: schedule both exams in the same month. Each application is valid for six months from the first requested exam date, per API's fee page, which gives room to retake but does not make two exams easier to fit into one stretch.

If you can't decide

Pick the one whose application deadline you can meet with a plan you believe in. If you are working toward the January 2027 510 window and it is too late, plan for May. If your piping experience is stronger, 570 in January or June 2027 is the natural start. A good plan starting now beats a rushed plan on a closer date. The exam schedule and fees guide covers the validity and rescheduling rules, and is API 510 worth it helps with the cost question. For the job side, read API 570 piping inspector salary and jobs.

Next step

Take the free 10-question check at /api-570#q1 to see how your piping knowledge stands. If vessels are your first target, run the API 510 check too. Then see the plans at /api-570/offer#plans, and ask the study buddy at /study-assistant for a plan built around your exam date.

FAQ

Is API 570 harder than API 510?

API publishes the same format for both, and we do not have a published comparison of difficulty. What differs is the equipment and the references, so the harder one is the one you know less about.

Can I hold both API 510 and API 570?

Yes. Each is a separate certification with its own application, experience record and recertification cycle. You must meet each one's experience requirement.

Do 510 and 570 cost the same?

API lists them in the same fee row. For 2027 initial certification that is $890 for members and $1,140 for non-members, and a late application adds $200.

Does studying for one help with the other?

Yes, through the shared format and the RP 571, 577 and 578 material. The calculation references and several publications differ, so plan new reading for the second exam.