Interim guidelines finalized for the use of ammonia cargo as fuel

Supplementary guidelines expected to be approved in May next year

Click to learn more about the new interim guidelines for the use of ammonia cargo as fuel.

Following a meeting of the IMO’s Sub-Committee on Carriage of Cargoes and Containers (CCC) in early September, the first-ever guidelines for use of anhydrous ammonia cargo as fuel on gas carriers were finalized. Reportedly “goal-based”, the guidelines will add supplementary text to Chapter 16 – Use of Cargo as Fuel in the IGC Code. The interim guidelines are expected to be formally approved at the next meeting of the IMO’s Maritime Safety Committee in May next year, which will also consider training requirements for seafarers on board ammonia-fueled vessels.

The draft guidelines were developed to support the use of the IGC Code paragraph 16.9 which requires an equivalent level of safety to using natural gas when using alternative fuels…

Specific requirements were developed for the use of ammonia cargo as fuel:

• Ammonia Fuel Supply Piping: Ammonia fuel supply piping, including double walled piping, should be coloured in a distinguishable way
• Gas Detection: A fixed ammonia gas detection system should be installed. Specific detection and shutdown limits have not been included
• Fuel plant ventilation: Ventilation capacity, including the ventilation inlet and outlet locations, should be supported by numerical calculations, such as a computational fluid dynamics (CFD) analysis
• Ammonia Release Mitigation System (ARMS): The uncontrolled and direct release of ammonia may only occur in emergency situations so the fuel supply system should include an ARMS capable of collecting and handling ammonia releases
• Spaces containing fuel consumers: Machinery spaces containing ammonia fuel consumers should be gas-safe machinery spaces

Description of the specific requirements for using ammonia cargo as fuel on gas carriers in the new interim guidelines. From Lloyd’s Register, “IMO Carriage of Cargoes & Containers (CCC 11) Summary Report” (Sept 2025)

According to Lloyd’s Register, the guidelines also include a series of “applicability provisions” that will apply to ships built on or after the date the guidelines enter into force (1 July 2028). These include specifics on fire systems, welded joints, automation, and cargo manifold connections.

The update from the CCC now formally removes the prohibition for ammonia-fueled, ammonia gas carriers to operate. All eyes now shift to the upcoming meeting of the IMO’s Maritime Environmental Protection Committee, where the new net-zero framework is expected to be approved.