Who Certifies Pressure Vessel Inspectors in the US: API, National Board and ASME

Short answer: no single body does. For in-service vessels, API certifies individuals as API 510 Pressure Vessel Inspectors, and the National Board commissions inspectors (In-service and Authorized Inspector commissions) who work for jurisdictions, insurers or accredited owner-user organisations. ASME does not certify inspectors; it writes the construction code and accredits Authorized Inspection Agencies. Which credential is legally required depends on your state or province.

The confusion is understandable. Three organisations, the state boiler and pressure vessel office, and in Canada a provincial regulator all appear in the same conversation, and each uses the word "authorized" in its own way. This guide maps who does what, for new construction and for in-service vessels, so that owners, QA managers and inspectors planning their careers can see which credential fits which job. It is based on the public pages of API, the National Board, ASME and ABSA; check the current documents before relying on any detail.

The four layers in one picture

Think of pressure vessel oversight as four layers that stack on top of each other:

1. The law (jurisdiction). States, some cities, and Canadian provinces pass boiler and pressure vessel laws. The jurisdiction decides which vessels are covered, which codes are adopted, who may inspect them, and what certificates of inspection or operation are needed. Its chief inspector enforces those rules.
2. The construction code (ASME). The ASME Boiler and Pressure Vessel Code, especially Section VIII for unfired pressure vessels, sets design, fabrication, examination and testing rules for new vessels. ASME accredits manufacturers to stamp vessels and accredits the Authorized Inspection Agencies that provide third-party inspection of that construction.
3. The commissioning body (National Board). The National Board of Boiler and Pressure Vessel Inspectors is made up of chief inspectors from US and Canadian jurisdictions. It commissions individual inspectors, accepts and accredits inspection organisations, publishes the National Board Inspection Code (NBIC, NB-23) used for in-service inspection, repair and alteration, and runs the R, NR and VR repair and test programmes.
4. The in-service industry code and personnel certification (API). API 510 is the refining and petrochemical industry's in-service inspection code for pressure vessels. API's Individual Certification Programs certify people as API 510 inspectors, alongside API 570 for piping and API 653 for tanks.

The table below summarises the roles.

New construction: the ASME stamp and the Authorized Inspector

When a fabricator builds a code-stamped vessel, an independent Authorized Inspector must verify that construction meets the ASME code before the stamp is applied. That inspector works for an Authorized Inspection Agency. ASME accredits the agency under its QAI-1 standard, Qualifications for Authorized Inspection, and the agency also needs National Board acceptance. The individual inspector holds a National Board commission with the appropriate endorsement, obtained by completing the National Board's AI course and examination and on-the-job training requirements.

So for new construction the answer is: ASME accredits the agency, the National Board commissions the person, and the jurisdiction recognises both. An API 510 certificate does not authorise someone to act as the Authorized Inspector for ASME stamping. Our guide on ASME Authorized Inspectors versus API inspectors covers this boundary in more depth, from the piping side.

In-service vessels: API 510 inspectors and National Board commissions

Once a vessel is in service, two systems run side by side, and many sites see both.

The API 510 route

API 510 covers in-service inspection, repair, alteration and rerating of pressure vessels. It requires that inspections under the code be performed or overseen by an inspector certified by API, the code's authorized pressure vessel inspector, who may be employed by the owner-user, a jurisdiction, an insurer or a contractor acting for the owner. API's certification is individual. According to API's public programme page, it is accredited by ANSI to ISO/IEC 17024, has a three-year term, and recertification requires evidence of recent pressure vessel inspection work, continuing professional development hours, and a periodic web-based quiz. Eligibility combines education and years of pressure vessel experience. The exam is delivered in person at Prometric test centres. See the API 510 certification overview and the official API ICP page for current details.

The National Board route

The National Board's In-service commission covers in-service inspection of boilers and pressure vessels, typically under the NBIC. To hold a commission, the National Board's public guidance says a candidate must be employed as an inspector by a jurisdiction, an Authorized Inspection Agency, an Owner-User Inspection Organization, a non-member enforcement agency, a federal inspection agency, or the National Board itself, and must meet education and experience credit requirements and pass the relevant examination. That employment link is the key difference from API 510: a National Board commission is tied to working for a recognised inspection organisation, while an API certification belongs to the individual.

Which one applies?

The jurisdiction decides. In many states, insured or jurisdiction-registered vessels are inspected by National Board commissioned inspectors working for the state or an insurance company, while refineries and chemical plants also run API 510 programmes. Some jurisdictions accept owner-user inspection programmes, where the owner's own commissioned inspectors or an accredited Owner-User Inspection Organization perform inspections. Some do not regulate certain vessels at all. Always check the specific state's boiler and pressure vessel law. For a side-by-side of the two in-service credentials, read API 510 versus NBIC commissioned inspector.

Where OSHA fits

OSHA does not certify pressure vessel inspectors. Its Process Safety Management standard, 29 CFR 1910.119(j), requires employers with covered processes to inspect and test process equipment, including pressure vessels, following recognized and generally accepted good engineering practices, and to document it. OSHA inspectors often treat API 510 as one of those practices, which is why so many refinery and chemical plant programmes require API 510 certified inspectors. But the certification requirement comes from the code the owner adopts and from the jurisdiction, not from OSHA issuing credentials.

Canada: provincial certificates on top of API and National Board

In Canada, pressure equipment is regulated provincially. Alberta is a good example of how the layers combine. ABSA, Alberta's pressure equipment safety authority, issues In-Service Pressure Equipment Inspector Certificates of Competency under its document AB-526. According to the current edition, a candidate needs relevant education and pressure equipment experience including in-service inspection experience, and must have passed the National Board In-service commission examination, the API 510 examination, or the API 570 examination, depending on the certificate type, before sitting ABSA's own exam on Alberta legislation and ABSA requirements. The piping-only certificate requires API 570; the vessels-and-piping certificate requires API 510; the certificate that also includes boilers requires a National Board In-service commission or examination. ABSA accepts the API and National Board exams as covering the technical body of knowledge.

Other provinces, such as Ontario through TSSA, have their own rules. The pattern is the same: API and National Board credentials are building blocks, and the province decides what is required on top. Check with the provincial regulator before planning work or a career move.

A worked example: one refinery, three inspectors

Consider a refinery replacing a separator drum and inspecting its existing vessels during a turnaround.

• The new drum is built by a fabricator holding ASME certification. An Authorized Inspector employed by an Authorized Inspection Agency, holding a National Board commission with the AI endorsement, verifies construction and witnesses the pressure test before the code stamp is applied. The manufacturer may also register the vessel with the National Board.
• Existing vessels are inspected under the refinery's API 510 programme. The owner's API 510 certified inspector writes inspection plans, reviews NDE data, calculates corrosion rates and remaining life, sets the next inspection dates under the code, and authorizes repairs.
• The jurisdiction in this state requires certificates of inspection for certain vessels. A National Board commissioned in-service inspector, working for the refinery's insurer, performs or accepts those inspections and reports them to the state.
• NDE technicians performing UT, RT, MT and PT on all three scopes are qualified under their employer's written practice to ASNT SNT-TC-1A or CP-189. Their certification is a separate, method-specific system and does not make them code inspectors.

Common misunderstandings

• "ASME certifies inspectors." ASME accredits organisations and writes codes; individual commissions come from the National Board.
• "API 510 is a licence." It is an industry certification of the individual. Whether it is required depends on the code adopted and the jurisdiction.
• "A National Board commission is portable like API." Commissions are tied to employment with a recognised inspection organisation; check the National Board's rules on continuation of commission.
• "An NDE Level II can sign off a vessel." ASNT certification qualifies a person to perform and interpret NDE; acceptance of the vessel for continued service rests with the code inspector.
• "One credential works everywhere." Canadian provinces and some US states add their own requirements.

For people planning a career

If you are a technician or welder asking how to become a pressure vessel inspector, the routes above suggest a sequence most people follow: build pressure equipment experience and NDE skills, then pursue the credential your target employers and jurisdiction expect. Refinery and petrochemical owner-users and contractors commonly ask for API 510; jurisdictions and insurance companies commission National Board inspectors after hiring them. Eligibility for both is based on education plus documented experience, so method certifications and inspection experience count. ASNT NDT certification in UT, MT, PT or RT is a common foundation for that experience. Atlantis does not provide API or National Board exam preparation; it offers ASNT SNT-TC-1A NDT training, for example NDT Level II training and ASNT certification guidance. For employers, our page on verifying an API inspector's certificate explains how to confirm a credential is current.

How Atlantis supports this

Atlantis NDT does not certify or commission inspectors, and it is not an Authorized Inspection Agency. Atlantis provides ASNT-certified NDE technicians working under ASNT Level III oversight, performing the UT thickness surveys, corrosion mapping, PAUT, TOFD, radiography, MT and PT that API 510 and NBIC inspection plans call for. Results go to the inspector of record, whether that is your API 510 inspector or a National Board commissioned inspector. See our pressure vessel inspection services and API 510 inspection support. Request a quote; we respond within 24 hours.

Frequently asked questions

Who actually certifies pressure vessel inspectors in the United States, and how do API, the National Board and ASME each fit in?

API certifies individuals as API 510 inspectors for in-service vessels. The National Board commissions inspectors employed by jurisdictions, insurers and accredited organisations, for new construction (AI) and in-service work (IS). ASME writes the construction code and accredits Authorized Inspection Agencies but does not certify individual inspectors. The state or province decides what is required.

Is API 510 required by law?

Not by federal law directly. It becomes required when an owner adopts API 510 as its practice, often to meet OSHA PSM expectations, or when a jurisdiction or province references it. Check your jurisdiction.

What is the difference between a National Board commission and API 510?

A commission is issued to inspectors employed by recognised inspection organisations and is linked to the NBIC and jurisdictional inspection. API 510 is an individual certification for in-service inspection under the API 510 code. Many in-service inspectors at refineries hold API 510; many state and insurance inspectors hold National Board commissions.

Does ASME certify inspectors?

No. ASME accredits Authorized Inspection Agencies under QAI-1 and manufacturers that apply the ASME certification mark. The Authorized Inspectors themselves hold National Board commissions.

What is an Authorized Inspection Agency?

An inspection organisation accredited by ASME under QAI-1, and accepted by the National Board, that employs Authorized Inspectors to verify construction to the ASME code. Many are linked to boiler and machinery insurers.

How do I become a pressure vessel inspector?

Gain pressure equipment and inspection experience, then pursue API 510 (individual, exam at Prometric centres) or a National Board commission (requires employment with a jurisdiction, AIA or owner-user organisation, plus exam and course where required). ASNT NDT certification is a common foundation.

Can an API 510 inspector sign off a new ASME vessel?

No. New construction requires an Authorized Inspector with a National Board commission working for an Authorized Inspection Agency.

What does an Owner-User Inspection Organization do?

It is an owner's in-house inspection organisation accredited by the National Board, where accepted by the jurisdiction, so that the owner's commissioned inspectors can inspect the owner's own equipment.

Is API 510 accepted in Canada?

It is used as a building block. In Alberta, ABSA's AB-526 accepts the API 510 or API 570 exam, or a National Board In-service examination, depending on certificate type, before its own certification exam. Other provinces have their own rules.

Are NDE technicians pressure vessel inspectors?

No. NDE technicians are certified by their employers in specific methods, usually to ASNT SNT-TC-1A or CP-189. They perform examinations; the code inspector accepts the vessel.

Need NDE for an API 510 or NBIC inspection plan? Send us your vessel list. Building NDE credentials for an inspection career? Ask about ASNT NDT training. Related reading: API inspector guide, NBIC NB-23 overview.