API 510, 570 or 653: which should you take first?

Candidates usually arrive at this question having been told the three API inspection certifications are “basically the same exam with different codes”. The format claim is true. The rest of it costs people a sitting.

Do API 510, 570 and 653 use the same exam format?

Yes, and this is the part that genuinely transfers. Each exam is 170 questions, of which 140 are scored and 30 are unscored pretest items that are not identified while you sit it. Each splits into 110 closed-book questions in 2 hours 45 minutes, a 45-minute break, then 60 open-book questions in 3 hours 45 minutes. Each is delivered in person at Prometric, with references supplied as on-screen PDFs rather than your own tabbed copies. Each passes at a scaled score of 400 on a 200-500 scale.

If you have sat one, you know how the day works. That is worth something — the rhythm of a two-session exam catches people out the first time, and it is the one thing you never have to learn twice.

How much do the reference lists actually overlap?

Much less than the shared format implies, and this is where the “same exam” story falls apart.

API 653’s construction standard is API 650. ASME Section VIII is not a referenced publication for API 653 at all. That single fact removes the entire pressure-vessel calculation spine that dominates an API 510 bank. A candidate who prepares for 653 by reworking their 510 material is studying for a different exam.

The direction of travel matters too: the March 2027 effectivity sheet moves API 650 to its 14th Edition and ASME BPVC Sections V and IX to their 2025 editions. The November 2026 window is the last one on the older March 2026 sheet, which still uses API 650 13th Edition and ASME BPVC 2023. Two candidates sitting four months apart can be examined on different editions of the same standard.

	API 510	API 570	API 653
Equipment	Pressure vessels	In-service piping	Aboveground storage tanks
Construction standard	ASME Section VIII	ASME B31.3	API 650
Format	170 questions, two sittings	170 questions, two sittings	170 questions, two sittings
Pass standard	Scaled 400 (200-500)	Scaled 400 (200-500)	Scaled 400 (200-500)
Recent windows	September, January, May	—	March, July, November

Which one should you take first?

The honest answer is the one covering the equipment you actually inspect, because that is where your existing judgement counts for most and where the certification is worth most to your employer.

If nothing forces the choice, note the calendar. API 653 windows run March, July and November with deadlines roughly two months earlier, on a different cycle from API 510’s recent September, January and May windows. If a deadline has already passed for one, the other may still be open — and a certification you sit this year beats a better-matched one you sit next year.

What does the published pass rate tell you?

For API 653, API’s April 2026 ICP status update gives the most recent published rate as the November 2025 administration: 503 candidates at 60.8%.

Resist doing anything with that number beyond noting it. It is one administration of one exam. Without equivalent published figures for 510 and 570 from comparable windows, it supports no ranking of difficulty, and a 60.8% pass rate says as much about who chose to sit that window as about the paper.

What actually transfers between them?

Three things, in descending order of usefulness:

1. The exam-day mechanics. Two sittings, a fixed break, no returning to the closed-book section once submitted, unanswered questions scored as incorrect, references on screen only during the open half.
2. Reading the effectivity sheet. The skill of checking which editions apply to your window, rather than to the window someone described in a forum post two years ago.
3. Nondestructive examination. All three include an NDE domain, and the physics does not change when the equipment does.

What does not transfer is the calculation work, the acceptance criteria, and the reference documents themselves. Budget your time accordingly.

Start with the free sample

Each of these has a ten-question free sample drawn from the real bank — enough to tell you whether the level is what you expected before you spend anything.

• API 510 practice questions — full guide
• API 570 practice questions — full guide
• API 653 practice questions — full guide