Cybutryne ban in hull coatings comes into force

Written by  
Muammer Akturk, ABS Senior Surveyor 

Muammer Akturk, ABS Senior Surveyor 

By Muammer Akturk, ABS Senior Surveyor 

Amendments to the International Convention on the Control of Harmful Antifouling Systems on Ships (AFS Convention) adopted by the IMO ban the presence of cybutryne in hull coatings beginning January 1, 2023.

Cybutryne is a chemical compound used in some antifouling hull coatings systems. When used in the outermost layer of hull coatings, cybutryne exhibits biocidal properties which prevent marine life from attaching to the hull coating’s surface.

When used as an anti-fouling agent, cybutryne leaches, following the physical mechanism well known to self-polishing anti-fouling paints, and then becomes available in the environment, together with other degradation products of its original formulation that can also be characterized as toxic and persistent.

At MEPC 71, a new output to amend Annex 1 to the AFS Convention was proposed to include controls on cybutryne and was agreed to include a new output on “Consideration of the initial proposal to amend Annex 1 to the AFS Convention to include controls on cybutryne”.

During the review process, the Technical Group developed the draft amendment to Annex 1 of the AFS Convention, and after several reviews, developed its final version and published amendments in IMO Resolution MEPC.331(76) prohibiting ships from applying or re-applying anti-fouling systems containing cybutryne on or after January 1, 2023.

AFS Convention Amendments

Introduction of new amendments to the AFS Convention prohibits usage of cybutryne (CAS No. 28159-98-0) in anti-fouling systems for new applications as well as for ships those already have applied with an anti-fouling system which contain cybutryne.

The amendments to the convention apply as follows:

New construction vessels with delivery date after January 1, 2023, shall be delivered as cybutryne free which is required to be declared by paint/coating manufacturer at the time of vessel’s delivery.

Existing vessels in operation shall comply with this requirement by the next scheduled anti-fouling system renewal survey after January 1, 2023, but no later than 60 months following the last application to the ship of an anti-fouling system containing cybutryne.

All existing ships bearing an anti-fouling system that contains cybutryne in the external coating layer of their hulls or external parts must either:

  • Remove the antifouling system; or
  • Apply a coating that forms a barrier (Sealing coating) to this substance leaching from the underlying non-compliant anti-fouling system.

Exceptions for existing coating systems are given for the following ship types and conditions:

  • Installations that have been constructed prior to January 1, 2023, and that have not been in dry-dock on or after January 1, 2023, specifically:
  1. Fixed and floating platforms;
  2. Floating Storage Units (FSUs);
  3. Floating Production Storage and Offloading (FPSOs);
  4. Ships not engaged in international voyages; and
  5. Ships of less than 400 gross tonnage engaged in international voyages, if accepted by the coastal state(s).

Guidance Available

In support of the controls on antifouling systems containing cybutryne, three guidance documents related to the AFS Convention have been updated to reflect the regulations which entered into force on January 1, 2023.

The revisions made to these three guidelines incorporate the previously adopted implementation schedule for the ban on cybutryne, and also provide additional details for confirming compliance, such as:

  1. Definition of compliance—sampling of the anti-fouling system paint should confirm cybutryne at a level which does not provide a biocidal effect (i.e., maximum 1,000 mg cybutryne per kg of dry paint);
  2. Tolerance Range—the tolerance range is 250 mg cybutryne per kg of dry paint (25%) in addition to the threshold value.
  3. Sampling—when testing for cybutryne, every sample to be taken in duplicate, providing one specimen for analysis and one for storage/back-up; and
  4. Analysis—details provided for one-step analysis of AFS samples to detect cybutryne.

Stakeholder actions

Shipowners, ship managers, ship operators, shipbuilders/shipyards, ship designers and paint manufacturers are recommended to be aware of this development and make the necessary arrangements accordingly when scheduling drydocking for existing vessels as well as newbuilding projects with delivery date after January 1, 2023.

During the planning stage, the paint manufacturer is to be consulted for compliance options such as the procurement of cybutryne-free paints or in the case of existing vessels with anti-fouling system containing cybutryne, arrangements to remove the existing anti-fouling system or apply a sealing coating in compliance with the above-mentioned requirements.

The anti-fouling system needs to be supplemented by a cybutryne-free declaration or statement issued by the paint manufacturer. Compliance shall be verified by an attending third party surveyor who will issue the new form of the IAFS Certificate.

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