API 510 Exam Guide 2026: Current Editions, Fees, and Worked Calculations

What Changed for the 2026-2027 API 510 Cycle

API has replaced the API 510 Publications Effectivity Sheet and Body of Knowledge. The set now in force covers the September 2026, January 2027, and May 2027 exam windows and replaces the September 2025 documents. If your tabs, notes, or course binder came from the previous cycle, several of your reference editions are now the wrong ones.

The headline change is the code year: API 510 questions are now written against the 2025 Edition of the ASME Boiler and Pressure Vessel Code. API 510 itself picked up Errata 2 (2025), and API RP 577 picked up Errata 1 (September 2025). The short list of testable API RP 571 paragraphs carried over unchanged from the September 2025 sheet.

Start free with API 510 practice questions and work the API 510 study guide chapter by chapter. But treat the effectivity sheet below as the scope of record, because that document, not any course outline, decides what a question writer is allowed to ask.

The Exact Reference Set for September 2026 - May 2027

Two scope limits in that sheet save real study hours:

• API RP 571 is not tested end to end. Only Section 2 (Terms and Definitions) plus 15 numbered paragraphs are in scope: 3.3, 3.8, 3.9, 3.11, 3.14, 3.15, 3.17, 3.22, 3.27, 3.35, 3.36, 3.37, 3.46, 3.61 and 3.67. The list is unchanged from the September 2025 sheet, which had swapped in boiler water and steam condensate corrosion (3.9), high-temperature H2/H2S corrosion (3.35) and naphthenic acid corrosion (3.46) in place of cooling water corrosion (3.20), mechanical fatigue (3.43) and sour water corrosion (3.58). Notes built before September 2025 still cover the wrong mechanisms.
• API 579-1/ASME FFS-1, API 580 and API 581 are not on the API 510 effectivity sheet. Fitness-for-service and risk-based inspection reach this exam only through API 510's own clauses, never as separate reference documents. Any prep source telling you to buy and tab API 579-1 for API 510 is pointing you at the wrong book.

The named PCC-2 Articles are 101, 201, 202, 209, 210, 211, 212, 215, 216, 304, 305, 312, 501 and 502, and the exam covers each Article together with its appendices.

One Exam Day, Two Very Different Tests

Two numbers matter more than the totals. The closed-book part gives you about 90 seconds per question, so recall has to be automatic. The open-book part gives you about 3 minutes and 45 seconds per question, which sounds generous until you spend two of those minutes hunting for a paragraph. API also notes that alternative item types (drag and drop, ordered response, multiple response, matching) are being phased into ICP exams, so practise reading a stem carefully rather than pattern-matching four lettered options.

2026-2027 Windows, Deadlines and Fees

API 510 runs three windows a year, and the application deadline lands roughly two months before the window opens.

Rescheduling is where candidates lose money twice. API charges $350 for a reschedule application, and Prometric separately charges $35 to move or cancel an appointment 30 to 60 days out and $70 from 5 to 29 days out. Inside five days you cannot move it at all. Once you have booked with Prometric you cannot change to a different testing window, and an application is valid for only 12 months from the first exam date you requested.

How API 510 Is Scored

API reports ICP results as a scaled score on a 200 to 500 scale, and the passing scaled score for every ICP exam is 400. There is no published percentage you can aim at, because API equates each form: the number of correct answers needed for 400 shifts slightly between forms so that the knowledge standard stays constant. API states plainly that its exams are not marked on a curve, and that the 30 pretest items are excluded from scoring entirely.

Results are fast. Prometric emails a final score report within 24 hours of testing, and API uploads final results to the ICP Portal within three business days, issuing the certification for applications without deficiencies.

API does publish API 510 pass rates, just not on the exam page. The ICP Statistics reports linked from the ICP Program Updates page list candidates, passes and the pass point for every administration. The April 2026 report shows 61.6 percent for January 2026 (424 of 688 candidates), 54.7 percent for September 2025 (561 of 1,024, the administration that went through standard setting) and 61.8 percent for May 2025 (618 of 1,000), each at a pass point of 400. Those are all-candidate figures; the report does not separate first-time takers from repeaters. Prep pages quoting a "47 percent first-time pass rate" next to a 150-question exam and a 70 percent cut score are not quoting API, and the question count and cut score on those pages are wrong as well.

Are You Eligible?

Qualification comes from Appendix B of the API 510 standard and combines education with pressure-vessel experience. That experience must have been gained in the last 10 years while employed by, or under contract with, an authorized inspection agency, and API verifies it after you apply.

Note the trap in row one: the single year for a degree holder must itself be inspection supervision or performance. Operations or maintenance time does not substitute.

The Calculations, Worked End to End

The Body of Knowledge tells you the calculation scope directly, and it is narrower than most courses imply. Only internal pressure loadings are considered, questions are aimed at existing vessels rather than new construction, and you must be able to work in both US customary and SI units. API also notes that the formulas and interval rules for corrosion and remaining life may appear in the closed-book part, so these cannot live on a tab.

1. Corrosion rate, remaining life and interval

A carbon steel shell course went into service in 2006 at a measured 0.500 in. The 2021 inspection read 0.412 in and the 2026 inspection reads 0.388 in. Required thickness is 0.250 in.

• Long-term rate (API 510, 7.1): (0.500 - 0.388) / 20 years = 0.0056 in/yr
• Short-term rate (API 510, 7.1): (0.412 - 0.388) / 5 years = 0.0048 in/yr
• Remaining corrosion allowance (API 510, 7.1): 0.388 - 0.250 = 0.138 in
• Remaining life (API 510, 7.2): 0.138 / 0.0056 = 24.6 years

The authorized inspector, in consultation with a corrosion specialist, selects the rate that best reflects current conditions; with no process change to justify the lower figure, the long-term rate governs here. Then apply API 510 Section 6:

• Internal or on-stream inspection (6.5): the lesser of half the remaining life (12.3 years) or 10 years, so 10 years
• External visual inspection (6.4): the lesser of 5 years or the internal interval, so 5 years
• If the remaining life had been 3.6 years, the interval may be the full remaining life up to a maximum of 2 years

The most common error is dividing t-actual by the corrosion rate. That gives 69.3 years and ignores the thickness you are not allowed to consume.

2. Required thickness and MAWP per ASME Section VIII, Division 1

For circumferential stress in a cylindrical shell, UG-27(c)(1) gives t = PR / (SE - 0.6P), valid while t is not more than 0.5R and P is not more than 0.385SE.

With P = 300 psi, corroded inside radius R = 24 in, allowable stress S = 17,500 psi and joint efficiency E = 1.0:

t = (300)(24) / ((17,500)(1.0) - (0.6)(300)) = 7,200 / 17,320 = 0.416 in

Rearranged for a rating problem, MAWP = SEt / (R + 0.6t). A shell measured at 0.500 in with a corroded inside radius of 24.125 in gives:

MAWP = (17,500)(1.0)(0.500) / (24.125 + 0.300) = 8,750 / 24.425 = 358.2 psi

The BOK also allows the Appendix 1 cylinder formula based on outside diameter, and it expects you to add or subtract corrosion allowance as the problem states.

3. Static head

Static head is always based on a specific gravity of 1.0, giving the conversion factor 0.433 psi/ft. A course 20 ft below the top liquid level carries 20 x 0.433 = 8.66 psi. Vessel MAWP is the part MAWP minus the head above it: 358.24 - 8.66 = 349.6 psi. Knowing the difference between vessel MAWP and vessel part MAWP (UG-98) is itself a testable point.

4. Heads

Using the same P, S and E, the two head types you must size are far apart:

• 2:1 ellipsoidal, UG-32(c): t = PD / (2SE - 0.2P) = 14,400 / 34,940 = 0.412 in
• Hemispherical, UG-32(e): t = PL / (2SE - 0.2P) = 7,200 / 34,940 = 0.206 in

A 2:1 ellipsoidal head sizes almost exactly like the shell; a hemispherical head needs about half the metal. If a problem hands you both a pressure and a thickness, it is asking whether the head meets Code, not what it would cost.

5. Joint efficiency

E is not a detail, it is a multiplier on every thickness answer. Repeat the shell above with E = 0.85 instead of 1.0:

t = 7,200 / ((17,500)(0.85) - 180) = 7,200 / 14,695 = 0.490 in, about 18 percent more metal.

Read the nameplate radiography marking first (UW-11), then Table UW-12 for the joint type: a Type 1 double-welded butt joint is 1.00 fully radiographed, 0.85 spot examined and 0.70 with no spot examination. UW-12(d) is the one people miss: a seamless shell section or head is treated as all Category A Type 1, with E = 1.0 only when the spot radiography requirements of UW-11(a)(5)(b) are met, and E = 0.85 when they are not.

6. Pressure test

UG-99(b) sets the hydrostatic test at 1.3 x MAWP x the lowest stress ratio, where the ratio is the allowable stress at test temperature divided by the allowable stress at design temperature. For the 349.6 psi vessel above, with S = 20,000 psi at test temperature and 16,600 psi at design temperature:

1.3 x 349.6 x (20,000 / 16,600) = 454.5 x 1.2048 = 547.6 psi

A pneumatic test under UG-100 uses 1.1 instead of 1.3. The old 1.5 factor is long gone, and it is the classic wrong answer.

7. Weld size

Convert a fillet weld throat to a leg dimension with the factor 0.7. A required throat of 0.25 in needs a leg of 0.25 / 0.7 = 0.357 in. Required weld sizes at openings come from UW-16.

What the BOK Says You Do NOT Have to Calculate

This list is the cheapest study hours on the whole exam, because it is 22 topics you can stop worrying about. API states that certification candidates are not expected to perform:

• external pressure calculations (you still need the UG-28 rules), nozzle calculations for external loads, and required thickness for wind, earthquake or other secondary stress loadings
• flange, ligament, tubesheet, stay and lifting-lug calculations
• relief valve sizing, proof testing and Zick analysis
• Code Cases and interpretations, cryogenic vessels below -50 F, and vessels for human occupancy
• ASME Sections UF, UB, UNF, UHA, UCI, UCL, UCD, UHT, ULW, ULT, UHX and UIG
• API 510 Section 9, the alternative rules for exploration and production vessels

Weld procedure review is similarly bounded: SMAW, GTAW, GMAW or SAW only, one process per WPS/PQR/WPQ, base metals limited to P-No. 1, 3, 4, 5 and 8, no dissimilar metal joints, and for exam purposes the lower transition temperature is 1330 F and the upper transformation temperature is 1600 F.

Splitting Your Study Time

Know cold (closed book): API 510 responsibilities and scope, corrosion rate and remaining life formulas, the Section 6 interval rules, repair versus alteration, rerating logic, damage mechanism recognition from the 15 in-scope RP 571 paragraphs, PRD basics from RP 576, and the shape of the UG-27 and UG-32 formulas.

Find fast (open book): Table UW-12 and UW-11 radiography markings, UG-99/UG-100 test rules, UG-84 and UCS-66 impact exemption curves, Section V article requirements, Section IX essential variables, and the 14 PCC-2 repair Articles.

A drill that works: set a two-minute timer, name a rule, and find the controlling paragraph. If you cannot land on it in two minutes, that tab is wrong. Do this with the 2025 Edition PDFs and the exact section list on the effectivity sheet, not with a full code book, because the exam only shows you the listed sections.

A 10-Week Plan Built on the Current Sheet

Tag every miss by cause: content gap, wrong edition, lookup speed, calculation setup, or misread stem. A pile of "wrong edition" misses in week 8 means your reference set, not your knowledge, is the problem.

Keeping the Certificate

API 510 is valid for three years, and recertification has three separate gates:

1. Work requirement, every 3 years. At least 20 percent of your time over the certification period must have been spent performing or supervising API 510 inspection activities. Inspectors who have not been active must sit the full exam again.
2. Continuing professional development, every 3 years. 24 CPD hours per cycle, spread across at least two activity categories. Since September 2025 API accepts only documentation stating verifiable instructional contact hours or CEUs; a certificate that merely lists "CPD hours" is rejected. Activities shorter than 50 minutes do not count.
3. Web quiz, every 6 years. A 25-question online open-book quiz on code changes over the past six years, with a four-hour window that may be paused up to three times. Fail it twice and you must reapply and sit the full exam.

Apply from 90 days before expiry through a 90-day grace period after. Miss that grace period and the certification expires, taking you back to a full application and a full exam.

Official Sources

• API 510 Pressure Vessel Inspector program page for exam structure, the current BOK and effectivity sheet, eligibility and recertification
• API ICP Schedules and Fees for windows, deadlines and every fee
• API ICP Examinations for Prometric scheduling, scaled scoring and score timing
• API ICP Program Updates for the twice-yearly ICP Statistics reports with pass rates by administration

Check those pages the week you apply. Every number in this guide was verified against them, but API changes effectivity sheets on a yearly cycle and the sponsor always wins.