DNV AoSS Compliance for Inspection Service Providers
Firms whose results DNV surveyors rely on. DNV lists roughly 23 service categories; those that bind inspection companies are ultrasonic thickness measurement of ship structures, non-destructive testing for offshore projects and offshore units or components, and in-water survey of ships. Personnel are qualified under employer-based certification, so a contracted Level III can sign the written practice and administer examinations for the firm.
Approval attaches to the legal entity for a named service and category, and covers only the subsidiary offices and the individually named personnel written into the certificate and its appendix. DNV's scheme issues an Approval of Service Suppliers certificate on form code AOSS 101, carrying an AOSS-format certificate number, a revision number, the service granted, the class programme it was granted under, and a category. Thickness measurement certificates are issued in accordance with Class Programme DNV-CP-0620 and typically carry Category I, authorising measurement on all types and sizes of ships; the certificate states it will be accepted for use with all rule sets published by DNV. Non-destructive testing on offshore projects and offshore units or components is granted under Class Programmes DNV-CP-0484 and DNV-CP-0640. Certificates list four explicit grounds for withdrawal.
Source: Three DNV-issued Approval of Service Suppliers certificates read in full: certificate AOSS0000ANW (Lloyd Werft Bremerhaven, thickness measurements on ships and mobile offshore units, Class Programme DNVGL-CP-0484, valid 2022-04-27 to 2025-04-26, form AOSS 101 rev 2021-03); certificate AOSS0000GND (International Inspection LLC, Seatac USA, thickness measurements, Class Programme DNV-CP-0620, valid 2023-03-25 to 2026-03-24, with appendix listing subsidiary offices and 17 named operators by ASNT level); certificate AOSS0000M2J (Check Your Ship OÜ, thickness measurements, DNV-CP-0620, issued 2025-12-16, form AOSS 101 rev 2024-10). DNV-CP-0484 and DNV-CP-0640 confirmed as the offshore NDT class programmes via DNV's own service pages and a supplier's published DNV approval announcement. DNV's UTM page confirms Pegasus as the mandatory UTM reporting tool for fleet-in-service vessels from 1 July 2017. The full text of DNV-CP-0620, DNV-CP-0484 and DNV-CP-0640 sits behind DNV's rules portal and was not read. Verified August 2026.
| Item | What applies | Why it matters |
|---|---|---|
| Authority | DNV AS (DNV Maritime), Høvik, Norway; certificates issued by DNV surveyors | The body that issues, audits and can withdraw |
| Applies to | Firms whose results DNV surveyors rely on. | 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 | Approval of Service Suppliers certificates for thickness measurement observed in the field run three years from issue — for example one valid 2022-04-27 to 2025-04-26 and another 2023-03-25 to 2026-03-24 — consistent with the three-year cap IACS UR Z17 places on thickness measurement firms. Certificates are re-issued at higher revision numbers between renewals when personnel or offices change. DNV lists four grounds for withdrawal on the certificate face: improperly carried out or improperly reported service, deficiencies found by the surveyor in the accepted operating system, failure to inform DNV of major changes affecting service quality, and changed or unfulfilled certificate conditions. | Diarise from the certificate date, not from memory |
| Methods in scope | UT (ultrasonic thickness measurement of ship structures), UT and advanced UT for offshore components, MT, PT, VT, ET and ACFM | Each method needs its own procedure and qualified personnel |
| Industries | Marine classification and statutory survey, Offshore projects, units and components, Ship repair and drydocking, Subsea inspection, Tankers, bulk carriers and gas carriers | Where this regime shows up in contracts |
Who does DNV AoSS apply to?
Firms whose results DNV surveyors rely on. DNV lists roughly 23 service categories; those that bind inspection companies are ultrasonic thickness measurement of ship structures, non-destructive testing for offshore projects and offshore units or components, and in-water survey of ships. Approval attaches to the legal entity for a named service and category, and covers only the subsidiary offices and the individually named personnel written into the certificate and its appendix.
Can an outsourced Level III sign for DNV AoSS compliance?
Yes. DNV AoSS 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 DNV AoSS audit ask for?
Application submitted through DNV's class portal against the applicable Class Programme, Quality system documentation and documented work procedures for the service applied for, List of supervisors and operators with certificates and levels, for entry into the certificate appendix, List of subsidiary offices to be covered, for entry into the certificate appendix, Equipment list with calibration and maintenance records. 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 DNV AoSS renewed?
Approval of Service Suppliers certificates for thickness measurement observed in the field run three years from issue — for example one valid 2022-04-27 to 2025-04-26 and another 2023-03-25 to 2026-03-24 — consistent with the three-year cap IACS UR Z17 places on thickness measurement firms. Certificates are re-issued at higher revision numbers between renewals when personnel or offices change. DNV lists four grounds for withdrawal on the certificate face: improperly carried out or improperly reported service, deficiencies found by the surveyor in the accepted operating system, failure to inform DNV of major changes affecting service quality, and changed or unfulfilled certificate conditions. 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 DNV AoSS findings?
A technician performing UTM whose name is not on the certificate appendix, because a certificate revision was never requested, UTM reports not produced through DNV's mandated Pegasus reporting tool for fleet-in-service vessels, Work performed from an office not listed among the subsidiary offices on the certificate, Measurement performed outside the granted category or outside the class programme scope on the certificate. 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 DNV AoSS cover?
UT (ultrasonic thickness measurement of ship structures), UT and advanced UT for offshore components, MT, PT, VT, ET and ACFM, RT. 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 DNV AoSS
Employer-based ASNT certification is accepted in practice for ship thickness measurement: DNV certificates issued under DNV-CP-0620 name authorised personnel individually in an appendix under the heading "Operator ASNT Level", recording each as Level II and flagging those additionally designated Supervisor. Because the individuals appear on the class certificate, adding or losing a technician is a certificate revision, not an internal HR matter — the certificate itself states that any alteration to the certified service operation system, including changes to UTM operators, must be reported to DNV immediately. The offshore NDT class programmes test that the supplier uses appropriate procedures and holds qualified and certified personnel governed by a written practice; an outsourced Level III can own that written practice and the procedures.
The audit sequence
- Register and apply through DNV's class portal, selecting the applicable Class Programme
- DNV reviews the submitted quality system, procedures, personnel and equipment documentation
- On-site audit of the firm and its named offices
- Practical demonstration of the service, witnessed by a DNV surveyor
- Issue of the Approval of Service Suppliers certificate (form AOSS 101) with category, class programme reference and an appendix naming subsidiary offices and authorised personnel
- Renewal audit before expiry; interim certificate revisions issued as personnel or offices change
Documents an auditor asks for
- Application submitted through DNV's class portal against the applicable Class Programme
- Quality system documentation and documented work procedures for the service applied for
- List of supervisors and operators with certificates and levels, for entry into the certificate appendix
- List of subsidiary offices to be covered, for entry into the certificate appendix
- Equipment list with calibration and maintenance records
- NDT written practice covering training, experience, examination, certification, performance, control, verification and reporting (offshore NDT scope)
- Report formats, and for UTM the reporting output DNV's Pegasus tool requires
- Notification records for any alteration to the certified service operation system
Findings firms get against DNV AoSS
- A technician performing UTM whose name is not on the certificate appendix, because a certificate revision was never requested
- UTM reports not produced through DNV's mandated Pegasus reporting tool for fleet-in-service vessels
- Work performed from an office not listed among the subsidiary offices on the certificate
- Measurement performed outside the granted category or outside the class programme scope on the certificate
- Supervisor designation on the certificate not matched by evidence of the required additional experience
- Calibration and verification records for thickness gauges incomplete or missing the reference block used
- Changes to the quality system or work procedures made without notifying DNV
- Offshore NDT written practice does not actually cover all of training, examination, certification, verification and reporting
Related: the DNV AoSS overview, outsourced ASNT Level III cover, written practice development, NDT procedure development, a programme gap assessment, interim Level III cover.