In-Service Inspection (ISI) Certification Guide [2026]
In-service inspection certification explained: API 510/570/653, National Board commissions, ABSA AB-526 and ASME Section XI, and how NDT examiner qualification differs.
What "ISI certification" actually means
In-service inspection (ISI) is the inspection of pressure equipment, piping, tanks and nuclear components after they enter service. There is no single "ISI certificate". Who may perform and sign in-service inspection depends on the jurisdiction and the asset, and the person signing the inspection is usually not the same person who performs the NDT. This guide separates the two.
Two different roles: the inspector and the NDT examiner
- The in-service inspector decides whether equipment is fit to continue in service, sets the next inspection date, and authorises repairs. This person holds an inspector certification or commission recognised by the jurisdiction or the code.
- The NDT examiner performs UT, RT, MT, PT, VT or ET and reports results. This person is qualified in each method, usually under an employer's written practice to ASNT SNT-TC-1A or ANSI/ASNT CP-189, with procedures approved by an NDT Level III.
An ASNT Level III certificate does not make someone an in-service inspector, and an inspector certification does not qualify someone to perform NDT. Many professionals hold both, but they are earned separately.
Inspector certifications by jurisdiction and asset
| Route | Who issues it | Typical scope |
|---|---|---|
| API 510 / API 570 / API 653 individual certification | American Petroleum Institute (API ICP) | In-service inspection of pressure vessels, process piping and aboveground storage tanks, mainly in owner-user programmes in the US and in many international refineries |
| National Board commission with an inservice (IS) endorsement | National Board of Boiler and Pressure Vessel Inspectors | Jurisdictional and Authorized Inspection Agency inspectors for boilers and pressure vessels where the jurisdiction requires it |
| ABSA in-service pressure equipment inspector certification | ABSA (Alberta's pressure equipment safety authority), under AB-526 | In-service inspection of pressure equipment in Alberta |
| Authorized Nuclear Inservice Inspector (ANII) | National Board commission, employed by an Authorized Inspection Agency | ASME Section XI inservice inspection of nuclear plant components |
For Alberta, see ABSA inspector certification. For the API programmes, see API 510, API 570 and API 653.
Eligibility in outline
Each body sets its own eligibility. API sets a combination of education and years of relevant experience for each exam and publishes the current rules and exam windows on api.org. The National Board requires employment with a jurisdiction, an Authorized Inspection Agency or a qualifying owner-user inspection organisation before a commission is issued. ABSA sets its own education, experience and examination requirements under AB-526. Check the issuing body's current documents before planning a timeline: there is no shortcut from an NDT certificate to an inspector certification.
What the NDT examiner needs for ISI work
- Method qualification to the employer's written practice (commonly SNT-TC-1A; CP-189 where the code or client requires it).
- Procedures approved by an NDT Level III and, where ASME Section V applies, meeting the relevant article.
- For ASME Section XI nuclear ISI, the additional qualification requirements of Section XI, including performance demonstration for ultrasonic examination under Appendix VIII.
- Records of certification, vision examinations and experience that an auditor can trace to each report.
How fitness for service fits in
When an in-service inspection finds damage beyond the acceptance criteria, the owner may commission an engineering fitness-for-service assessment, often to API 579-1/ASME FFS-1. That assessment is engineering work, separate from both the inspector's and the NDT examiner's roles. Atlantis NDT does not perform fitness-for-service assessments.
Salary context
Pay for in-service inspectors and NDT examiners varies widely with region, sector, method and whether the role is staff or contract. Inspector certifications such as API 510 are commonly associated with higher pay than single-method NDT roles, but published figures differ by source and year. Use current regional surveys rather than a single number.
Where Atlantis NDT fits
Atlantis NDT trains NDT personnel to ASNT SNT-TC-1A and provides ASNT NDT Level III services — written practices, procedure approval and examinations — for the NDT side of in-service inspection programmes. Atlantis NDT does not offer API, National Board or ABSA exam preparation. Affordable, accessible and fully customizable — contact us to discuss your programme.
Frequently Asked Questions
Q1: Is there one ISI certification I can get?
No. In-service inspector certification depends on the jurisdiction and asset — API 510/570/653, a National Board commission, ABSA certification in Alberta, or ANII for nuclear Section XI work.
Q2: Does ASNT Level III qualify me as an API 510 inspector?
No. API 510 is a separate certification with its own eligibility and exam. ASNT Level III is an NDT qualification.
Q3: Who certifies in-service inspectors in Alberta?
ABSA, under AB-526. See ABSA inspector certification.
Q4: Who qualifies the people doing the NDT during ISI?
Their employer, under a written practice such as ASNT SNT-TC-1A or CP-189, with procedures approved by an NDT Level III.
Running this as a programme, not a one-off
If you are responsible for an inspection programme rather than a single job, the recurring problem is rarely the code — it is keeping measured thickness, damage-mechanism assignment and next-inspection dates in one defensible place. Asset integrity management software covers keeping measured thickness readings per CML in one place, so the RBI (API 580/581) and fitness-for-service (API 579) work your integrity team or its specialists carry out starts from measured data rather than default rates. Atlantis supplies the NDT data and the software to hold it; it does not perform RBI or FFS assessments.