API 510 Compliance for Inspection Service Providers
NDT firms and contract inspection agencies serving refinery, chemical and gas-processing owner-users. The programme belongs to the owner-user, but the examiner hours, the NDE procedures, the Level III and frequently the Authorized Inspector are bought in. Personnel are qualified under employer-based certification, so a contracted Level III can sign the written practice and administer examinations for the firm.
It reaches any firm supplying thickness measurement, weld examination, on-stream inspection or turnaround inspection on in-service pressure vessels, and any firm signing inspection reports that feed the owner-user's mechanical integrity file. API 510 is not a certificate a service company holds; it is the owner-user's programme, and it defines the roles your people fill. It separates the API Authorized Pressure Vessel Inspector, who holds API's central certification and evaluates results against the code, from the examiner, who performs the nondestructive examination and does not evaluate against API 510 unless specifically trained and authorised to do so by the owner-user. Selling into this regime means selling examiner hours plus the paperwork that makes them admissible: an accepted written practice, Level III-approved procedures, current examiner certifications and calibrated equipment. Inspection types are external visual, internal or on-stream, and thickness measurement, each running on its own interval cap, and each producing records the owner-user must be able to defend.
Source: API 510 certification page, api.org, accessed 21 August 2026 — verified for the education and experience eligibility ladder (BS or 3+ years military technical service plus 1 year; 2-year degree or 2 years military plus 2 years; high school diploma plus 3 years; no formal education plus 5+ years, each with a supervision component), the 7.5-hour exam day, 170 questions of which 140 are scored, split 110 closed-book and 60 open-book, the three-year recertification cycle, the 20% time requirement, 24 CPD hours per three-year cycle and the 25-question web quiz every six years. API ICP Schedules & Fees page — verified for $875/$1,125 initial, $745/$855 recertification, $350 reschedule, and the 2026 exam windows. API ICP Policies page — verified that the term of certification is three years and the open-book quiz is required every six years for 510, 570, 653, 936 and 1169. API Standard 510 announcement page — confirms the 11th edition, which added a detailed section for the analysis of inspection results; the October 2022 publication date comes from reseller listings, not from API's own page. Inspection-interval caps commonly cited for the 11th edition (internal or on-stream at the lesser of half the remaining corrosion life or ten years; external visual at the lesser of five years or the internal/on-stream interval) were cross-checked against two independent secondary summaries and NOT against the code text — confirm against API 510 before publishing them as figures.
| Item | What applies | Why it matters |
|---|---|---|
| Authority | American Petroleum Institute. API's Individual Certification Programs (ICP) office certifies the Authorized Pressure Vessel Inspector; the inspection programme itself is owned and enforced by the owner-user, and by the boiler and pressure vessel jurisdiction where the state has adopted API 510 | The body that issues, audits and can withdraw |
| Applies to | NDT firms and contract inspection agencies serving refinery, chemical and gas-processing owner-users. | Whether this binds your firm at all |
| Personnel certification | Employer-based — the firm certifies its own, under a qualified Level III | Decides whether an outsourced Level III can sign for you |
| Renewal | There is no company certificate to renew. The individual API 510 certificate runs for a three-year term. Recertification requires that the inspector has spent a minimum of 20% of his time over the most recent three-year certification period performing or supervising inspection activities, and has completed 24 CPD hours within each three-year cycle; an online open-book quiz of 25 questions with a four-hour limit is required every six years. API's published fees for the 510, 570 and 653 programmes are $875 USD for members and $1,125 for non-members for initial certification, $745 and $855 for recertification, and $350 to reschedule an exam. The 2026 API 510 exam windows are 2–23 January and 8–29 May 2026. | Diarise from the certificate date, not from memory |
| Methods in scope | UT, UT thickness, PAUT, TOFD, RT, MT | Each method needs its own procedure and qualified personnel |
| Industries | Refining, Petrochemical, Chemical manufacturing, Gas processing and LNG, Fertilizer and ammonia | Where this regime shows up in contracts |
Who does API 510 apply to?
NDT firms and contract inspection agencies serving refinery, chemical and gas-processing owner-users. The programme belongs to the owner-user, but the examiner hours, the NDE procedures, the Level III and frequently the Authorized Inspector are bought in. It reaches any firm supplying thickness measurement, weld examination, on-stream inspection or turnaround inspection on in-service pressure vessels, and any firm signing inspection reports that feed the owner-user's mechanical integrity file.
Can an outsourced Level III sign for API 510 compliance?
Yes. API 510 accepts employer-based certification, which places the obligation on the employer and allows a contracted Level III to write and sign the written practice, approve procedures and administer examinations. The Level III must be qualified in each method they sign for, and the employer still owns the records.
What documents does a API 510 audit ask for?
Owner-user inspection programme document naming the Authorized Inspector and defining what the examiner is authorised to evaluate, Current API 510 certificate for each Authorized Pressure Vessel Inspector, with the recertification due date, NDE written practice, and the Level III approval on each method procedure, Examiner certification records and current annual eye examinations, Thickness measurement location and condition monitoring location drawings, and the full reading history against those identifiers. Auditors open records before they open manuals, because a manual describes intent while records show practice. The most common failure is a documented system that does not match what the technicians actually do.
How often is API 510 renewed?
There is no company certificate to renew. The individual API 510 certificate runs for a three-year term. Recertification requires that the inspector has spent a minimum of 20% of his time over the most recent three-year certification period performing or supervising inspection activities, and has completed 24 CPD hours within each three-year cycle; an online open-book quiz of 25 questions with a four-hour limit is required every six years. API's published fees for the 510, 570 and 653 programmes are $875 USD for members and $1,125 for non-members for initial certification, $745 and $855 for recertification, and $350 to reschedule an exam. The 2026 API 510 exam windows are 2–23 January and 8–29 May 2026. Firms that diarise renewal from the certificate date rather than from the last audit avoid the lapse that forces a full reapplication.
What are the most common API 510 findings?
Examiner taking thickness readings and also signing the evaluation against API 510 without written authorisation from the owner-user, Inspector certificate expired, or CPD hours not documented for the three-year cycle, Thickness data reported with no corrosion rate and no remaining-life calculation, so the next inspection date has no basis, NDE procedure that does not cover the technique actually used — a generic manual UT procedure used for encoded corrosion mapping is the common case. These recur because they are records problems rather than capability problems — the work is being done correctly and the evidence is not being kept.
Which NDT methods does API 510 cover?
UT, UT thickness, PAUT, TOFD, RT, MT, PT, VT. Each method in scope needs its own approved procedure and personnel qualified in that specific method; a Level III qualified in ultrasonics cannot sign for radiography.
Personnel certification under API 510
Split, and the split is the commercial point. The Authorized Pressure Vessel Inspector must hold API 510 certification — a central, third-party certification examined by API and delivered through Prometric. No employer can issue it and no outsourced Level III can substitute for it. The NDE examiner side is entirely employer-based: examiners are certified under an employer's written practice built on ASNT SNT-TC-1A, ANSI/ASNT CP-189 or ACCP, so an outsourced Level III can write and approve the method procedures, administer and grade examinations and recommend certification, with the employer's designated certifying authority signing. API additionally operates ultrasonic examiner qualification programmes — QUTE, QUSE, QUSE-PA and QUPA — that some owner-users specify on top of ASNT certification for corrosion mapping and weld phased array.
The audit sequence
- Owner-user issues the inspection programme and defines the scope of contracted work
- Contractor's written practice, NDE procedures and personnel records are reviewed and accepted by the owner-user's Authorized Inspector before mobilisation
- Pre-job qualification on site: examiner certificates, eye examinations and equipment calibration verified
- Examination performed to procedure — the examiner records data, the Authorized Inspector evaluates it against API 510
- Inspection report issued, remaining life and next inspection date calculated, and any repair or alteration approved by the Authorized Inspector
- Contractor records tested in the owner-user's or a third party's audit, usually inside a PSM mechanical-integrity or supplier audit, because API does not audit inspection companies
Documents an auditor asks for
- Owner-user inspection programme document naming the Authorized Inspector and defining what the examiner is authorised to evaluate
- Current API 510 certificate for each Authorized Pressure Vessel Inspector, with the recertification due date
- NDE written practice, and the Level III approval on each method procedure
- Examiner certification records and current annual eye examinations
- Thickness measurement location and condition monitoring location drawings, and the full reading history against those identifiers
- Corrosion rate and remaining-life calculations supporting the next inspection date
- Inspection report signed by the Authorized Inspector, kept distinct from the examiner's data report
- Repair and alteration records, including welding procedure specifications, procedure qualification records and the Authorized Inspector's acceptance
- Equipment calibration records and certification of ultrasonic calibration blocks
Findings firms get against API 510
- Examiner taking thickness readings and also signing the evaluation against API 510 without written authorisation from the owner-user
- Inspector certificate expired, or CPD hours not documented for the three-year cycle
- Thickness data reported with no corrosion rate and no remaining-life calculation, so the next inspection date has no basis
- NDE procedure that does not cover the technique actually used — a generic manual UT procedure used for encoded corrosion mapping is the common case
- Repeated identical thickness readings year on year with no explanation of how the data was taken
- Level III approval on a procedure with no evidence that the Level III's own certification is current
- Contractor's written practice never formally accepted by the owner-user before work started
- External visual, internal or on-stream, and thickness measurement intervals tracked in separate systems, so the shortest governing cap is missed
Related: the API 510 overview, outsourced ASNT Level III cover, written practice development, NDT procedure development, a programme gap assessment, interim Level III cover.