News 02 Jul, 2020

New ABS NOx Guidelines Launched

The American Bureau of Shipping (ABS) has published two sets of guidelines to provide ship owners with best practice for IMO Tier III Nitrogen Oxide (NOx) compliance for new build and retrofitted ships.

Nitrogen Oxide (NOx) is one of the gaseous pollutants from ships that is regulated by the International Convention for the Prevention of Pollution from Ships (MARPOL Annex VI(1)), published by the International Maritime Organization (IMO).

Under Regulation 13 of MARPOL Annex VI, three tiers of Nitrogen Oxide (NOx) emission limits have been set for diesel engines with a power output higher than 130 kW, i.e., IMO Tier I, Tier II and Tier III. Each Tier limits the NOx emission to a specific value based on the rated engine speed.

Diesel engines for installation on ships constructed on or after 1st January 2016 are subject to IMO Tier III requirements when a ship is operating in a NOx Tier III Emission Control Area (NOx ECA) as designated under Regulation 13 of MARPOL Annex VI.

The guidelines include an overview of available technologies for NOx compliance, and a number of considerations for the selection of equipment to comply with MARPOL Annex VI(1)).

Additionally, the process for obtaining statutory and class approval and subsequent certification are also covered in the guidelines, including two new NOx and Low Emissions Vessel (LEV) notations.


The new NOx notation recognizes vessels with engines complying with appropriate MARPOL requirements. The new LEV notation recognizes low emission vessels equipped with engines complying with EU Regulations.

Gareth Burton, ABS Vice President, Technology said: “The industry is looking for assistance on understanding requirements and demonstrating compliance. This advisory and the NOx and Low Emissions Vessel (LEV) notations are a fantastic means both for guiding vessel owners and operators through the maze of regulation and technology and highlighting that a vessel meets the regulations. This is another example of ABS responding to shipping’s needs with practical, accessible and timely guidance”

The ENVIRO or the ENVIRO+ notations are available to vessels after the effective date of the guidelines and for existing vessels which currently maintain an ES notation provided the requirements contained in the below guidelines are fully satisfied.

A copy of the ABS Advisory on NOx Tier III Compliance can be read here ABS Advisory on Nox Tier III Compliance.

A copy of the ABS Guide for the Environmental Protection Notations for Vessels - June 2020 can be read here ABS Guide for the Environmental-Protection-Notations For Vessels.

Members can obtain further information from the Club’s Loss Prevention Department at lossprevention@westpandi.com