Written Practice for DNV AoSS
DNV AoSS names this requirement as "NDT written practice covering training, experience, examination, certification, performance, control, verification and reporting (offshore NDT scope)". The employer's Level III owns it, and a contracted Level III can author and sign it.
The finding auditors record against this document is: Offshore NDT written practice does not actually cover all of training, examination, certification, verification and reporting. 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 |
|---|---|---|
| Regime | DNV Approval of Service Suppliers (AoSS) | Enforced by DNV AS (DNV Maritime), Høvik, Norway; certificates issued by DNV surveyors |
| Document | Written Practice | the document that defines how the employer qualifies and certifies its own NDT personnel |
| Owner | the employer's Level III | The signature an auditor traces back |
| Where it is checked | Issue of the Approval of Service Suppliers certificate (form AOSS 101) with category, class programme reference and an. | Usually against a sampled job, not in isolation |
| Common failure | A technician performing UTM whose name is not on the certificate appendix, because a certificate revision was never requested | The gap between the manual and the job file |
What must a written practice contain under DNV AoSS?
It has to satisfy DNV AoSS as DNV AS (DNV Maritime), Høvik, Norway; certificates issued by DNV surveyors enforces it: the document that defines how the employer qualifies and certifies its own NDT personnel. The test is not completeness on paper but traceability — an auditor picks a finished job and works backwards to this document, so anything it claims must be demonstrable on that job.
Who signs the written practice for DNV AoSS?
The employer's Level III. Because this regime accepts employer-based certification, that role can be filled by a contracted Level III rather than a staff appointment, provided they are qualified in the methods they sign for.
How does a DNV AoSS auditor test this document?
By sampling. They take a completed job, find the technicians and equipment used, and trace each back through this document to the evidence behind it. A document that reads well but cannot survive that trace is the most common finding across every regime, not just this one.
How long must DNV AoSS records be kept?
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. Retention is set by the regime and by the client contract above it, and the longer of the two governs. Firms that set one retention period for everything and document it fare better at audit than firms tracking different periods per record type and losing track.
Does a generic template satisfy DNV AoSS?
No. A downloaded template describes a generic firm, and the first question an auditor asks is whether the document describes THIS firm — its methods, its equipment, its people, its actual workflow. Templates are a starting structure; the content has to be the firm's own or the trace fails immediately.
What happens if this document is missing at a DNV AoSS audit?
It is a finding, and depending on the regime it can suspend the certificate rather than merely generate a corrective action. The related finding auditors record most often is: A technician performing UTM whose name is not on the certificate appendix, because a certificate revision was never requested
Where this sits in the DNV AoSS evidence pack
- 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
Personnel certification context
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.
Related: the DNV AoSS overview, outsourced ASNT Level III cover, written practice development, NDT procedure development, a programme gap assessment, interim Level III cover.