Article

The International Association of Classification Societies (IACS) has revised its Unified Requirement UR M78 to include ammonia as an approved fuel for marine engines, marking a significant step towards decarbonization in the maritime industry. The updated Rev.4 expands the scope to cover ammonia-fuelled reciprocating internal combustion engines alongside other fuels.

Key highlights include new safety requirements for gas return/recovery systems, ammonia release mitigation systems, and enhanced measures to address toxic hazards and explosion risks. Revised design standards for gas piping and components, as well as continuous monitoring for crankcase ventilation, are also introduced. This revision will be applied uniformly by IACS Member Societies for type approval applications dated from July 1, 2027, providing a regulatory framework that supports shipowners and manufacturers in transitioning to zero-carbon shipping.