Owner-User Inspection Organizations (NB-371) Explained
Short answer: an Owner-User Inspection Organization (OUIO) is a company that owns or operates boilers and pressure vessels and is accredited by the National Board under procedure NB-371 to have its own National Board commissioned inspectors carry out in-service inspection of that equipment. It needs a quality management system meeting NB-381, inspectors and supervisors holding a National Board Inservice (IS) commission, a National Board review, and authorization from each jurisdiction. Accreditation lasts three years.
This guide is for mechanical-integrity managers, inspection supervisors and plant engineers deciding whether to become an OUIO, preparing for accreditation, or working alongside one as a contractor. It explains what NB-371 Revision 11 (approved by the National Board's Board of Trustees on 10 May 2025) requires, how the route compares with an API 510 owner-user programme, how jurisdictions treat it, and where contracted NDE fits. It paraphrases the National Board's public procedure documents; always work from the current revision on nationalboard.org.
What an OUIO is and what it is allowed to do
The National Board describes an OUIO as an owner-user of pressure equipment that maintains an established inspection programme, whose organization meets the National Board's requirements and is acceptable to the jurisdictional authority. In plain terms, instead of relying on a state inspector or an insurance company's inspector for statutory in-service inspections, the owner employs its own commissioned inspectors and is accredited to use them.
NB-371 sets out the scope in three layers:
- In-service inspection. An accredited OUIO may perform in-service inspections of items it owns or operates for jurisdictional or federal compliance.
- Repairs and alterations (optional). It may extend its scope to repair and alteration inspections for National Board Inspection Code (NBIC) compliance.
- Signing NBIC report forms. With that extended scope, it may perform the authorization, in-process and acceptance inspections for repairs and alterations to its own pressure-retaining items, including signing the National Board report forms. This applies whether the work is done by the OUIO's own R Certificate of Authorization or by another R Certificate holder working on the OUIO's equipment. The quality management system must describe how this is done, including the interface with the jurisdiction or federal government.
The key limitation is ownership: an OUIO inspects equipment it owns or operates. It is not an Authorized Inspection Agency selling inspection to other companies. Third-party in-service inspection agencies are accredited under a different National Board procedure (NB-369).
The people: IS commissions, R endorsements and inspector supervisors
NB-371 is built around National Board commissioned inspectors, not around API certification.
- Inspectors. The OUIO must employ inspectors holding an active National Board Inservice Commission (IS). If the scope includes repair and alteration inspections, they also need the R endorsement.
- Owner-user inspector supervisors. The OUIO must employ one or more owner-user inspector supervisors with overall responsibility for inspection activities, for carrying out the duties described in NB-263 (RCI-1, Rules for Commissioned Inspectors) and for monitoring inspector performance. Supervisors also need an active IS commission, with the R endorsement where repairs and alterations are in scope. At least one supervisor must attend the National Board review.
- Training and instructions. The OUIO must provide ongoing training to maintain competence, give inspectors written instructions on their duties (including the duty to inspect in line with jurisdictional requirements), and give them the organizational freedom and authority to carry out their responsibilities.
How inspectors get commissioned during accreditation is spelled out in an attachment to NB-371. Inspectors who already hold an active commission and endorsements with a previous employer can have them transferred to the new OUIO by submitting a change-of-employment application (NB-216-1). Inspectors without a commission apply for the Inservice Inspector Commission (NB-120-1) through the National Board Business Center, name the prospective OUIO as their employer, meet the education and experience requirements of RCI-1, complete any required training and pass the commission examination. In both cases the commission is issued to the OUIO when the Certificate of Accreditation is issued.
Note that NB-381 requires an agreement that the commission and endorsements remain the property of the inspection organization and become invalid when employment ends. Commissions are tied to the employer, which matters for staffing plans.
The quality management system: what NB-381 asks for
An OUIO must have and maintain a written quality management system (QMS) manual that meets NB-371 and NB-381, Quality Management Systems for Inspection Organizations (Revision 6, also approved in May 2025). NB-381 applies to all the National Board's inspection-organization programmes and doubles as a checklist for applicants and review teams. Its elements, paraphrased:
| NB-381 element | What the manual must cover | Practical note for owners |
|---|---|---|
| Title page, statement of authority, organization | Company, scope, a signed management statement, an organization chart and lines of authority | Inspectors need freedom to raise quality problems without being overruled by production |
| QMS responsibilities and scope | Who owns the QMS, who administers it day to day, how inspectors get technical help from the supervisor, and the type and extent of inspection activity | Revise the manual whenever the scope changes |
| Document control | Preparation, revision, approval and distribution; submission of revisions to the National Board for acceptance | Minor editorial changes do not need National Board acceptance |
| Training | Orientation and periodic training, including the NBIC, RCI-1, jurisdiction training and the QMS itself, with records | Keep schedules, topics and evidence of completion |
| Records | Responsibilities and retention | Compliance records for at least five years; personnel qualification records while the person works and for at least five years after |
| Corrective action | Identifying, resolving and preventing recurrence of adverse conditions | Expect the reviewer to sample real findings |
| In-service inspection | Developing, approving and controlling written inspection procedures | Inspectors must be able to tell at which stages inspections are due |
| Repairs, alterations and replacements | Authorizing and accepting work, including signing NBIC forms (where in scope) | Needs the R endorsement |
| Reporting | Action on unsafe conditions and escalation of conflicts | Define the higher authority in writing |
| Control of contracted services | How services are contracted and controlled | This is where NDE contractors sit |
| Audits | Annual internal audits of the QMS and RCI-1 audits of inspectors | Keep audit records until the next National Board survey |
| Independence, impartiality and integrity | Independence requirements, conflict-of-interest agreements | Inspectors must not inspect items they designed, built or supplied |
| Sample forms | All forms used, marked as samples | Form titles in the text must match the samples |
Accreditation step by step
- Provisional certificate. The organization applies for a Provisional Certificate of Accreditation on form NB-111. The provisional certificate lets it employ National Board commissioned inspectors during accreditation and lets its employees apply for commissions. It does not allow the organization to perform inspections.
- Commission the inspectors. Transfer existing commissions or have staff qualify and pass the Inservice commission examination, as described above.
- Write and implement the QMS. Prepare the manual to NB-381 and run the programme so there are records to show. A controlled copy of the manual goes with the application.
- Apply for accreditation. Holders of a provisional certificate (and renewing OUIOs) apply on form NB-463. The applicant names the locations where the QMS will be fully demonstrated; not every facility under the same programme has to be visited if documentation is available to the review team.
- Review. The National Board reviews the organization, its manual and facilities and verifies implementation. The review team leader may be a representative of the member jurisdiction where the organization is located; if the jurisdiction declines, where there is no jurisdiction, or where inspections are for federal compliance, the National Board performs the review.
- Report and decision. The review team leader prepares a qualification review report (NB-244) recommending issue, renewal or withholding of the certificate.
- Certificate. When all requirements are met, the Certificate of Accreditation is issued. It expires three years after issue or renewal, and a controlled copy of the approved manual is sent to the National Board.
- Jurisdiction authorization. Separately, the OUIO must obtain authorization from the jurisdictional authority to provide inspection services.
Two rules catch multi-site owners. First, facilities in more than one jurisdiction need a separate Certificate of Accreditation for each jurisdiction. Second, renewal applications must be made at least six months before the certificate expires, so the renewal clock starts well before the expiry date on the wall.
OUIO compared with an API 510 owner-user programme
Owners often confuse two things that both get called "owner-user inspection". The National Board OUIO is an accreditation built on National Board commissions. An API 510 programme is an owner-operator inspection organization run to the API code, staffed by API-certified inspectors. They can coexist at the same plant.
| Aspect | National Board OUIO (NB-371) | API 510 owner-operator programme |
|---|---|---|
| Who recognises it | National Board accreditation, plus jurisdiction authorization | Self-declared under the code; some jurisdictions accept or approve it |
| Inspector credential | National Board Inservice commission (IS), R endorsement for repairs | API 510 Authorized Pressure Vessel Inspector certification |
| Quality system | Written QMS to NB-381, accepted by the National Board | Owner's inspection programme and procedures as API 510 requires |
| What it satisfies | Jurisdictional or federal in-service inspection; NBIC repair/alteration acceptance if in scope | Owner's in-service inspection, commonly used as PSM RAGAGEP |
| Renewal | Certificate every three years after a review | Individual API certifications renew on API's cycle |
| Typical users | Owners in jurisdictions that inspect pressure vessels and accept OUIOs | Refineries, chemical plants and midstream operators everywhere |
Many large operators run both: an API 510 programme for planning, intervals and the PSM file, and OUIO accreditation (or a state owner-user agency) so that their inspectors can sign the statutory inspections in states that regulate vessels. The difference between the two inspector credentials is explored in API 510 vs NBIC commissioned inspector.
How jurisdictions treat owner-user inspection
Accreditation from the National Board does not by itself authorize an OUIO to inspect in a state; NB-371 requires the organization to obtain authorization from the jurisdictional authority. State laws also have their own owner-user language, which may or may not reference NB-371.
- Pennsylvania. The National Board jurisdiction synopsis notes that operators may seek approval and registration as an owner/user inspection agency through the Department of Labor and Industry.
- Virginia. The Boiler and Pressure Vessel Safety Act provides for pressure vessel operators to seek approval and registration as an owner-user inspection agency.
- Oklahoma. The synopsis records adoption of API 510 for vessels within its scope, which is a different route to owner-led inspection.
- Texas. The state boiler law excludes pressure vessels (other than steam drums of process steam generators), so OUIO status for vessels is not a state requirement there; OSHA PSM still applies.
- Federal locations. An OUIO inspecting at locations under federal control must state in its manual that the governmental entity has the authority to interpret and enforce the rules for those items, and define who resolves conflicts.
Because the arrangements vary, read our overview of who has authority over pressure equipment in the US and confirm with the chief inspector for each state.
Canada. Provinces run their own owner-user schemes. In Alberta, owners with an accepted pressure equipment integrity management system hold an ABSA Certificate of Authorization Permit, with requirements set in AB-512; a harmonized version, AB-512H, has been endorsed by Alberta, Saskatchewan and Manitoba. In Ontario, TSSA publishes a guideline for companies requesting certification for owner-user self-inspection. These are provincial programmes, separate from NB-371.
Where contracted NDE fits in an OUIO
An OUIO's commissioned inspectors are responsible for the inspection, but they rarely perform every examination themselves. Ultrasonic thickness surveys, corrosion mapping, radiography, phased array and surface methods are commonly contracted. NB-381 expects the QMS to describe how contracted services are contracted and controlled, and the National Board review team will look at how that works in practice.
For the OUIO, controlling NDE contractors usually means:
- defining which methods and techniques may be used for which damage mechanisms, and approving the contractor's procedures;
- checking that the contractor's personnel are certified for each method under a written practice (commonly ASNT SNT-TC-1A) and keeping evidence available;
- specifying report content so that each inspection record identifies the item, the date, the examiner, the method and the results, which also satisfies OSHA PSM record requirements in covered processes;
- having the commissioned inspector review and accept the results, decide whether further examination is needed, and record the inspection on the required forms.
The NDE contractor is a supplier inside the OUIO's system. It does not become part of the accredited organization and does not sign the jurisdictional inspection. Choosing between internal and contracted resources is discussed in in-house vs third-party inspection.
A worked example: three plants, one decision
A chemical company runs three plants in a state that registers unfired pressure vessels and puts them on a fixed certificate cycle. Today an insurance company's commissioned inspectors perform the certificate inspections, while the company's own API 510 inspectors plan inspections and keep the PSM file. Outages are often delayed waiting for the outside inspector.
The company weighs OUIO accreditation. It would need to commission at least one supervisor and enough inspectors with the IS commission, write an NB-381 manual that reuses much of its API 510 programme, run it long enough to show records, apply, pass the review and obtain state authorization. Because all three plants are in one state, one Certificate of Accreditation covers them, and the review can be held where inspection activities are controlled. If it later acquires a plant in another state, a second certificate is needed. It also decides whether to add the repair/alteration scope so that its inspectors can sign R-1 and R-2 forms for contractor repairs, which requires R endorsements.
The NDE scope at the plants does not change. What changes is whose inspector reviews it and signs the certificate inspection.
Common mistakes
- Assuming an API 510 certification is enough to staff an OUIO. NB-371 requires National Board IS commissions.
- Starting inspections under a provisional certificate. The provisional certificate allows hiring and commissioning, not inspecting.
- Applying for renewal late. The application is due at least six months before expiry.
- Treating one accreditation as nationwide. Each jurisdiction needs its own certificate and authorization.
- Leaving contracted NDE outside the QMS. The manual must say how contracted services are controlled.
- Letting inspectors report to production. NB-381 requires organizational freedom and independence provisions.
How Atlantis supports owner-user inspection organizations
Atlantis NDT works as a controlled NDE supplier inside an OUIO's or API 510 owner's programme. ASNT-certified technicians under ASNT Level III oversight perform UT thickness and CML surveys, corrosion mapping, PAUT, TOFD, radiography with crews licensed where the work is done, MT, PT, VT and ET, using written procedures and certifications your commissioned inspectors can audit. Reports carry the item, date, examiner, method and results. Your inspector remains the inspector of record; Atlantis is not an accredited inspection organization and does not sign jurisdictional inspections. See pressure vessel inspection services, piping CML inspection or request a quote within 24 hours.
Frequently asked questions
What is an owner-user inspection organization?
An owner or operator of boilers and pressure vessels accredited by the National Board under NB-371 so that its own commissioned inspectors can perform in-service inspections of the equipment it owns or operates.
What is NB-371?
The National Board procedure for accrediting Owner-User Inspection Organizations. Revision 11 was approved by the Board of Trustees on 10 May 2025.
What are the NB-371 accreditation requirements?
A QMS manual meeting NB-381, inspectors and supervisors with an active Inservice commission (plus R endorsement for repairs), a National Board review, and jurisdiction authorization.
How long does an OUIO Certificate of Accreditation last?
Three years from issue or renewal. Apply for renewal at least six months before expiry.
Can an OUIO inspect equipment for other companies?
No. NB-371 covers items owned or operated by the organization. Third-party in-service inspection agencies are accredited separately.
Can OUIO inspectors sign R-1 and R-2 forms?
Yes, if the OUIO's scope includes repair and alteration inspections and the inspectors hold the R endorsement, for work on its own items.
Do I need a separate OUIO certificate for each state?
Yes. Facilities in more than one jurisdiction need a separate Certificate of Accreditation for each jurisdiction.
Is an OUIO the same as an API 510 owner-user programme?
No. An OUIO is National Board accreditation using commissioned inspectors; an API 510 programme is run by API-certified inspectors under the API code. Many owners run both.
What is the difference between NB-371 and NB-369?
NB-371 accredits owner-user inspection organizations; NB-369 accredits Authorized Inspection Agencies performing in-service inspection for others.
Can an OUIO use contracted NDE?
Yes. NB-381 requires the QMS to describe how contracted services are controlled; the commissioned inspector reviews and accepts the results.
Does a provisional certificate allow inspections?
No. It lets the organization employ commissioned inspectors and lets staff apply for commissions while accreditation proceeds.
Running an OUIO or API 510 programme and need reliable NDE? Talk to us about your next outage, review NBIC repairs and alterations, or see how API 510, 570 and 653 satisfy OSHA PSM. You can also ask for a scope review.
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