API 510 application, exam and recertification fees are set by API Individual Certification Programs (API ICP) and vary by membership status — check the current fee schedule at api.org for exact figures. Atlantis NDT does not run API 510 exam preparation; our pressure-vessel work is ASNT Level III consulting on NDE procedures and inspection-data review, scoped per programme — contact us for a tailored quote.
Reviewed by Atlantis NDT founder Anoop Rayavarapu, ASNT NDT Level III in five methods (UT, RT, MT, PT, VT), with 11+ years of international NDT field experience. This page summarises the API 510 11th edition (October 2022) and the API 510 certification as published by API.
Eligibility and Exam Format (api.org)
Eligibility combines education with pressure-vessel experience within the last 10 years: a BS in engineering or technology plus 1 year; a 2-year degree plus 2 years; a high school diploma plus 3 years; or no formal education plus 5 or more years — each including at least 1 year in supervision or performance of inspection. No NDT certification is required. The exam has 170 questions (140 scored) over about 7.5 hours at Prometric test centers: 110 closed-book questions, then 60 open-book questions with the references provided on screen. Remote proctoring ended in September 2024. API 510 windows run in January, May and September. API reports a scaled score.
Referenced Publications (Sept 2026 – May 2027 windows)
API 510 11th edition (with Errata 1 and 2); API RP 571 3rd edition (16 listed mechanisms, including amine SCC, brittle fracture, caustic SCC, chloride SCC, CUI, erosion, high-temperature H2/H2S corrosion, HTHA, naphthenic acid corrosion, sulfidation and wet H2S damage); API RP 572, RP 576, RP 577 and RP 578; ASME BPVC 2025 Section V (listed articles), Section VIII Division 1 (listed parts) and Section IX; and ASME PCC-2 (listed articles). API RP 580/581 and API 579-1 are not on the API 510 exam list.
Inspection Intervals Under API 510
External visual inspection: at the lesser of 5 years or the required internal/on-stream interval. Internal or on-stream inspection: at the lesser of one-half the remaining life or 10 years; when remaining life is under 4 years the interval may be the full remaining life up to 2 years. On-stream inspection may substitute for internal inspection when entry is impossible or when the code's conditions are met (for example corrosion rate under 0.005 in./yr, remaining life over 10 years, no environmental cracking or hydrogen damage). An RBI assessment per API RP 580 may set intervals instead, with engineer and inspector review at least every 10 years where intervals exceed 10 years. Pressure-relieving devices default to 5 years for typical process service and 10 years for clean, non-fouling, non-corrosive service. Pressure tests are not part of routine inspection.
Corrosion Rates and Remaining Life
Long-term and short-term corrosion rates are calculated from thickness data and the inspector selects the rate that best represents current conditions; remaining life = (t_actual − t_required) / corrosion rate, with t_required from the construction code (for ASME VIII Div. 1, UG-27 for shells and UG-32 for heads). A common error is confusing nominal thickness with required thickness. The future corrosion allowance is used when calculating MAWP, not in the remaining-life formula.
Repairs, Alterations, Rerating and the FFS Handoff
Repairs and alterations are authorized by the inspector before work starts (with the engineer for alterations and specified repairs), use WPS/PQR qualified to ASME Section IX, and are accepted by the inspector on completion; a pressure test is normally required after an alteration. Rerating requires calculations, testing or NDE alternatives per the code, and updated nameplate/records. When damage falls outside API 510's acceptance rules, the owner may repair, rerate, replace or commission an engineering fitness-for-service assessment per API 579-1/ASME FFS-1. Atlantis NDT does not perform FFS or RBI assessments.
A working API 510 inspector reads a vessel by service, not by type. Hydroprocessing reactors in hydrogen service are screened for high-temperature hydrogen attack against the API RP 941 Nelson curves; coker drums cycle thermally and develop fatigue cracking at skirt-to-shell welds; crude-unit equipment sees sulfidation and naphthenic acid corrosion; amine units need PWHT and wet fluorescent MT for amine cracking; vessels in wet H2S service are examined for HIC, SOHIC and SSC. Inspection methods are chosen to find the credible mechanism (API RP 571 and RP 572), not by habit.
Heat Exchangers
Shell-and-tube exchangers are inspected under API 510 for the shell and channels; tube bundles are commonly examined with eddy current on non-ferromagnetic tubes and with IRIS, RFT or NFT techniques on ferromagnetic tubes, under the owner's procedures. Atlantis NDT's eddy current training is ASNT SNT-TC-1A-based.
WPS, PQR, and ASME Section IX
Repairs and alterations are welded to a WPS qualified by a PQR per ASME Section IX. The inspector checks the WPS against the PQR essential variables (process, P-Number, F-Number, preheat, PWHT, and so on); a field PWHT cycle that falls outside the qualified range invalidates the qualification and is a common audit finding. Atlantis NDT's ASNT Level III consulting supports NDE procedures and written practices for these programmes.
Frequently Asked Questions
Q1: API 510 vs API 570 vs API 653 — which first?
A: API 510 for pressure vessels, API 570 for piping, API 653 for storage tanks. They are independent; choose the one matching the equipment you inspect, because experience must relate to that equipment.
Q2: What is a realistic pass rate?
A: API's ICP status update (April 2025) showed per-window API 510 pass rates of roughly 54–69% between 2020 and early 2025.
Q3: How long is the API 510 exam?
A: About 7.5 hours at a Prometric test center: 110 closed-book questions in 2.75 hours and 60 open-book questions in 3.75 hours, with tutorial and break. References are provided on screen.
Q4: Recertification cycle?
A: Every 3 years: at least 20% of working time on inspection activities and 24 CPD hours, plus an online web quiz every 6 years.
Q5: Do Aramco / ADNOC require API 510 for vessel inspection?
A: Many national oil companies and refiners specify API 510-certified inspectors for in-service pressure-vessel inspection; check the specific operator standard and contract.
Q6: When does API 510 hand off to API 579?
A: When thickness, pitting or flaws fall outside API 510's own acceptance rules and the owner chooses an engineering fitness-for-service assessment rather than repair, rerate or replacement.
Q7: Pricing?
A: API sets its exam fees. For Atlantis NDT services: affordable, accessible, fully customizable — pricing varies by region and scope, quote on request.
Most API 510 work runs on ultrasonic thickness and flaw data. Candidates can strengthen their UT skills and practise on the simulator; owner-operators can bring in Atlantis for the NDE and data review behind their API 510 programme, with the Authorized Inspector staying their own.
API ICP sets API 510 eligibility on a sliding scale: a bachelor's degree in engineering or technology plus 1 year of pressure-vessel experience, a two-year technical degree plus 2 years, a high school diploma plus 3 years, or 5 years with no formal education. The examination is one day at a Prometric center, 110 closed-book then 60 open-book questions, and certification runs a 3-year cycle.
Two things decide an API 510 result, and neither is reading volume. The first is the eligibility file: API ICP requires employer-attested experience in in-service inspection, repair, alteration and rerating of pressure vessels, and applications stall on documentation that cannot be substantiated far more often than on exam performance. The second is calculation speed. The open-book half is scored against API 510, ASME Section VIII Division 1 (UG-27 for shells, UG-32 for heads), ASME Section V, ASME Section IX, API Recommended Practices 571, 572, 576, 577 and 578, and ASME PCC-2. Marks concentrate in minimum required thickness, MAWP, short-term and long-term corrosion rate, remaining life, and inspection-interval derivation. The recurring error is treating nominal mill thickness as required thickness. Candidates who know where each clause sits in the electronic references and drill the arithmetic to automaticity pass; candidates who read widely and calculate rarely do not. Editions are locked per exam cycle, so buy from the current body of knowledge.
Source: API Individual Certification Programs (API ICP) — API 510 Pressure Vessel Inspector Certification, Body of Knowledge and Publications Effectivity Sheet; API 510, Pressure Vessel Inspection Code, 11th Edition; ASME BPVC Section VIII Division 1.
Technically reviewed by Anoop Rayavarapu — ASNT NDT Level III (UT, RT, MT, PT, VT)
API 510 eligibility by education level — API ICP minimum documented experience (US applicants)
Highest education attained
Minimum documented experience
Experience must be in
Most common cause of application rejection
BS or higher in engineering or technology
1 year
Supervision, design, or inspection of in-service pressure vessels
A degree in an unrelated discipline claimed as engineering or technology
Two-year degree or certificate in engineering or technology
2 years
The same work at technician or engineer grade
A certificate from a non-technical program
High school diploma or equivalent
3 years
The same work, attested by the employer
Self-declared hours with no employer attestation
No formal education
5 years
The same work, attested by the employer
Gaps in the employment record across the qualifying period
API ICP publishes the governing eligibility table, the publications effectivity sheet and the current fee schedule at api.org. Confirm all three against your specific exam window before applying — the effectivity sheet is what fixes which editions you may bring.
Does API 510 certification give me legal authority to inspect pressure vessels in the United States?
No. API 510 is a competence credential issued by API ICP. Legal authority over in-service pressure equipment in the US belongs to the state or municipal jurisdiction, which normally works through a National Board commission held under the NBIC. Many refiners accept an API 510 holder as their owner-user inspector; jurisdictional repairs and R-stamp work still route through a commissioned inspector.
How do API 510, API 570 and API 653 differ, and which should I sit first?
API 510 covers pressure vessels, API 570 in-service piping, API 653 aboveground atmospheric storage tanks. Sit the one your current work already documents experience toward, because the experience file gates the application, not the exam. Refinery and petrochemical inspectors commonly hold all three; a technician who never touches tanks gains only a renewal obligation from API 653.
When does an API 510 evaluation stop and an API 579 fitness-for-service assessment start?
API 510 evaluates remaining thickness against code-minimum and sets the next inspection date. When general metal loss, local metal loss, pitting, blisters and hydrogen-induced damage, weld misalignment, crack-like flaws, creep or fire damage exceed API 510 screening, the assessment moves to API 579-1/ASME FFS-1, whose Parts address each damage class at three assessment levels. API 579-1 is not on the API 510 exam effectivity sheet; FFS assessments are engineering evaluations.
Can I bring my own code books into the API 510 exam, and can they be tabbed?
No. The exam is computer-based at Prometric test centers, and in the 60-question open-book part the publications named on the effectivity sheet for your window are provided electronically on screen. Personal books, tabs and notes are not allowed, and the 110-question closed-book part allows no references. Study from the editions on the sheet, because clause numbering moves between editions.
How does an employer prove an inspector's API 510 certification is still current at audit?
API ICP publishes a public certification search returning holder name, certification number and expiry date, and that lookup is what auditors use. The failure mode is not a fraudulent certificate; it is a genuine one that lapsed mid-contract. Currency belongs in a system that warns before certifications, vision exams and radiation badges expire, not in a personal calendar.
Which NDT method certification does an API 510 inspector still need?
API 510 authorises interpretation and disposition, not examination. Thickness readings, radiographs and phased-array data must be produced by personnel certified to ASNT SNT-TC-1A, ANSI/ASNT CP-189 or ISO 9712 in the applicable method, under a procedure a Level III approved. An API 510 inspector who takes their own UT readings needs UT Level II qualification to do so defensibly.
Answering the questions candidates actually ask
API 510 — Pressure Vessel Inspector covers in-service inspection, repair, alteration and rerating of pressure vessels. The examination is built around API 510 itself, ASME Section VIII Division 1 as the construction code, ASME Section V for the examination methods, ASME Section IX for welding qualification, and API 571, 572, 576 and 577 as supporting recommended practices.
What decides the result
The marks concentrate in minimum required thickness and MAWP, corrosion rate and remaining life, inspection interval derivation, and the rules governing repair, alteration and rerating. The genuine discriminator between candidates who pass first time and those who do not is the MAWP and minimum-thickness calculations under time pressure, and knowing which clause governs a repair versus an alteration — which is a practised skill rather than a knowledge one, and it is the reason drilling beats reading.
Related routes: API 570 for piping · API 653 for storage tanks. Holding more than one widens the scopes you can be assigned to, and client specifications frequently name a combination rather than a single credential. The efficient order is normally whichever certification your current work is already generating documented experience toward.
Frequently Asked Questions
Am I eligible for API 510 certification?
Eligibility is set by a combination of education and documented experience, and the required experience falls as the level of formal education rises — an engineering degree needs materially fewer documented years than entry from the shop floor. The experience has to be in work relevant to in-service inspection, repair, alteration and rerating of pressure vessels, and it must be attested by an employer rather than self-declared. The most common reason an application is delayed is not the exam at all: it is experience documentation that does not stand up.
What is on the API 510 examination?
The examination is built around API 510 itself, ASME Section VIII Division 1 as the construction code, ASME Section V for the examination methods, ASME Section IX for welding qualification, and API 571, 572, 576 and 577 as supporting recommended practices. The parts candidates most often lose marks on are minimum required thickness and MAWP, corrosion rate and remaining life, inspection interval derivation, and the rules governing repair, alteration and rerating — and, in the open-book portion, simply locating the governing clause quickly enough. In practice the discriminator is the MAWP and minimum-thickness calculations under time pressure, and knowing which clause governs a repair versus an alteration.
How should I prepare for API 510?
Time spent on calculations is the strongest single predictor of passing, ahead of total reading time. The pattern that works is: buy the current-edition references and tab them properly, read every referenced publication once, then drill the routine calculations until they are automatic, then sit timed full-length practice exams and remediate only the weak areas those expose. Candidates who read widely and calculate rarely tend to fail.
Which edition of the references applies?
The body of knowledge names the exact editions in force for each exam cycle, and it is locked well before the first window. Buying the wrong edition is the most expensive avoidable mistake in preparation, because the clause numbering moves. Check the current body of knowledge before purchasing anything, and see what changed in the current cycle.
How long does API 510 certification last, and what is recertification?
Certification runs for a defined term and then requires recertification, either by examination or by documented continuing work in the discipline depending on the scheme and how long you have held it. Recertification lapses are a routine audit finding and they are entirely avoidable — the renewal date belongs in the same system that blocks dispatch on any other expired qualification, not in a personal calendar.
Is API 510 worth holding alongside other certifications?
Usually yes, and the combinations matter more than the individual credentials. Holding more than one API inspector certification widens the scopes you can be assigned to and is frequently what a client specification asks for, while ASNT or ISO 9712 method certification underpins the NDT the inspection itself relies on. The right sequence is normally the certification your current work already generates experience toward.
Preparing with support
Structured preparation materially outperforms self-study on these examinations, mainly because they reward judgement and clause navigation rather than recall. Preparation runs year-round: self-paced online through Atlantis LMS, with an ASNT NDT Level III answering questions, and on-site for employer groups preparing together. Send a training enquiry; we reply within one business day.
Should we mandate API 510, 570 and 653 as the minimum certification for every in-service inspection role?
Not uniformly — mandate by scope, not by job title. API 510 governs pressure vessels, 570 piping and 653 aboveground storage tanks; an inspector who never touches tanks gains nothing from 653 except a renewal obligation. The defensible policy most operators land on is: the certification matching the equipment class is mandatory for the inspector of record, a second is expected for senior or multi-unit roles, and the third is optional unless the site actually has that equipment. Write it that way and it survives audit; write "all three for everyone" and you will grant exceptions within a quarter, which is worse than not having the rule.
Where regional variance bites: the API ICP scheme is recognised globally, but some jurisdictions and national operators additionally require their own approval on top (Saudi Aramco, ADNOC and QatarEnergy each run inspector-approval registers). A global policy should therefore specify the API certification as the floor and name the local approval as an additional requirement per region, rather than pretending one credential clears every gate.
What's the practical difference between an ASNT NDT Level II and a code inspector certification like API 510?
They answer different questions and neither substitutes for the other. An ASNT NDT Level II is a method qualification — this person is competent to set up, perform and interpret ultrasonic (or RT, MT, PT…) examination against a procedure. An API 510 certification is an equipment and code qualification — this person can determine inspection intervals, evaluate findings against the code, and sign that a vessel is fit to return to service. The Level II produces the data; the API inspector decides what it means for the asset.
In practice a competent inspection function needs both, and the confusion costs money in one specific way: sending an ASNT Level II to perform an API 510 inspector's duties produces a report that will not be accepted by the jurisdiction, and paying for API certification for a technician who only performs examinations buys a credential they will never exercise.
What does it actually cost to sponsor a field technician through API 510?
The cost has three parts and only one of them is an invoice: the certifying body's examination fee (published on api.org and revised periodically — always price from their current schedule, not a figure quoted online), preparation whether formal training or structured self-study, and the part employers consistently underestimate — the productive time lost. Candidates who pass typically put in a substantial block of study, and the code books themselves are a real line item.
The comparison that matters is not the total but the alternative: contracting an API inspector for the same scope, indefinitely. For a company with recurring vessel work, sponsorship usually pays back inside the first year of the certificate's life. For one-off work, it does not. Ask us to scope a sponsorship programme and we will tell you honestly which of those two your workload actually is.
Have a question shaped like these? Put it to an ASNT Level III — we answer the specific case, not the general one.