IMO updates guidelines for NLS tank cleaning additives

Eda Zenic -

The International Maritime Organization has issued updated guidance (MEPC.1/Circ.590/Rev.1) for approving and using cleaning additives in cargo tank washing under MARPOL Annex II. This guidance includes a reporting form in the appendix titled "REPORTING FORM FOR THE SUBMISSION OF DATA FOR THE EVALUATION OF NLS TANK CLEANING ADDITIVES", which provides a standardized format for manufacturers to submit data for approval.

The guidance applies to cleaning additives used in tanks carrying noxious liquid substances (NLS). Additives must meet strict environmental criteria, including a requirement that harmful Category X components are only allowed if they are biodegradable and account for less than 10% of the additive’s composition.

Additives are evaluated by the ESPH Technical Group, and approved products are listed in Annex 10 of the MEPC.2/Circular. Commercially branded additives have a 7-year expiry, while pure products are listed without expiry for universal use. Submissions must include the appendix reporting form, a complete breakdown of the additive’s composition, safety data sheets, and usage instructions. All components must have GESAMP Hazard Profiles (GHPs), and trade names are not accepted. Products with carcinogenic, mutagenic, or environmentally harmful components are either restricted or rejected.

The guidance only applies to additives used for cleaning NLS residues. Other products, such as solvents or those intended for MARPOL Annex I applications, are excluded.

Manufacturers are responsible for ensuring that submitted formulations remain consistent and for reporting any changes for re-evaluation. They must also record additive use in the ship’s Cargo Record Book. Administrations review submissions before forwarding them to the ESPH Technical Group for evaluation.

This updated circular replaces the previous version and emphasizes compliance with MARPOL standards. The appendix reporting form is essential for ensuring submissions are complete and meet environmental requirements.