Magnetic Particle Testing (MT) Requirements Under DNV AoSS

System performance is verified rather than assumed: lift tests on yokes and field indicator checks are dated records an auditor expects to see per shift or per job. DNV AoSS, enforced by DNV AS (DNV Maritime), Høvik, Norway; certificates issued by DNV surveyors: Employer-based ASNT certification is accepted in practice for ship thickness measurement: DNV certificates issued under DNV-CP-0620 name authorised.

An auditor examining MT asks for yoke or bench unit, ammeter, field indicators, lift-test weights and the consumables in use. 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.

Magnetic Particle Testing under DNV AoSS — procedure, personnel and evidence
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
Method	Magnetic Particle Testing (MT)	Needs its own procedure and its own qualified personnel
Procedure approval	The employer's Level III, qualified in this method	The signature an auditor traces
Other methods in scope	UT (ultrasonic thickness measurement of ship structures), UT and advanced UT for offshore components, PT, VT, ET and ACFM, RT	Each needs separate qualification
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.	Applies to the personnel certification behind this method

Does DNV AoSS require a separate procedure for MT?

Yes. Every method in scope needs its own written procedure, approved by someone qualified in that method, describing technique, equipment, calibration, scanning or coverage, acceptance criteria and reporting. A single combined "NDT procedure" covering several methods is a finding under every regime that names procedures individually.

Who can approve a MT procedure under DNV AoSS?

A Level III qualified in MT. Because DNV AoSS accepts employer-based certification, that Level III may be contracted rather than employed — but their own qualification must cover MT, and an auditor will check that before accepting the signature.

What MT records does a DNV AoSS audit sample?

The approved procedure, the technician's MT certification on the date of work, and the equipment evidence — yoke or bench unit, ammeter, field indicators, lift-test weights and the consumables in use. The auditor works backwards from a finished job, so every item has to reconcile with the report and its stated acceptance criteria.

What is the most common MT finding at audit?

Yoke lift test not recorded, or field adequacy not demonstrated for the geometry. It is a records failure rather than a technique failure — the examination was performed correctly and the evidence supporting it cannot be produced, which under DNV AoSS is recorded the same way as not having done the work.

Can a technician certified elsewhere perform MT under DNV AoSS?

Not automatically. Employer-based certification ends when the holder leaves, so the new employer must certify them under its own written practice. Prior training and documented experience transfer as evidence; the certificate itself does not.

What equipment evidence does MT need under DNV AoSS?

Calibration status traceable to the day of use, covering the instrument and its accessories — probes, cables, blocks and reference standards for ultrasonics; sources and densitometers for radiography. An in-calibration instrument with an out-of-calibration reference block fails the same way as an uncalibrated one.

How do MT requirements differ from the other methods in DNV AoSS?

Scope, qualification and evidence are method-specific, so the differences are real rather than administrative. DNV AoSS also covers UT (ultrasonic thickness measurement of ship structures), UT and advanced UT for offshore components, PT, VT, ET and ACFM, and each carries its own procedure, its own personnel qualification and its own equipment evidence.

Personnel certification for MT

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.