The International Association of Classification Societies (IACS) has published the latest edition of Unified Requirement (UR) M10, which introduces new safety requirements to protect internal combustion engines from crankcase explosions, in response to the shift towards alternative fuels in response to environmental regulations and sustainability goals.
According to IACS, the safety risks associated with these fuels cannot be overlooked. Crankcase explosions, a critical hazard in engine operation, become even more concerning in the context of gas and low flashpoint fuels.
The revised URM10, specifically designed for engines running on gas or low flashpoint fuels, addresses the unique challenges posed by these fuel types thereby ensuring that safety measures keep pace with evolving technologies and thus safeguarding maritime operations.
Revision 5 of UR M10 builds on key existing safety standards essential for protecting against crankcase explosions. These include the requirements for crankcases to be constructed to withstand the internal pressures generated by potential explosions. For engines with a crankcase volume exceeding 0.6m³, additional explosion relief valves are required to safely manage the excess pressure. Furthermore, a crankcase explosion relief valve must be in compliance with type testing procedures stipulated in IACS UR M66, as incorporated in IACS Members Rules, ensuring they meet the unified technical requirements fit for safety purposes, designed to safeguard against explosions.
The new edition of UR M10 was achieved through extensive collaboration with key industry stakeholders, including engine manufacturers. This cooperative effort ensures that the new guidelines are not only effective but also practical and feasible for real-world application, reflecting the latest technological advancements in engineering practices and safety protocols. In this latest edition, IACS has introduced the following improvements to address the safety requirements specific to engines fuelled by gas or low flashpoint fuels:
- Airflow Requirements: Technical conditions for the external airflow into the crankcase have been specified for engines fueled with gas or low flashpoint fuels, ensuring operational safety.
- Lower Explosive Limit (LEL): The revised UR M10 now defines the Lower Explosive Limit (LEL) for gas, fuel vapours, or mixtures in the crankcase, contributing to enhanced safety measures.
- Crankcase Pressure Control: To prevent interference with critical safety devices, such as oil mist detection systems during forced extraction of the crankcase atmosphere.
- Safety Evaluation: Engines fuelled by gas or low flashpoint fuels must undergo a comprehensive safety evaluation to ensure gas concentrations remain below the LEL or that explosion risks are duly mitigated.
- Explosion Risk Mitigation: Predefined measures for reducing the risk of crankcase explosions have been introduced, ensuring greater protection against potential hazards.
- Engine Bearing Monitors: Engine bearing temperature monitors or equivalent devices are now classified as essential safety components.
- Comprehensive Documentation: Documentation detailing the effectiveness of the safety measures to prevent explosive conditions is to be provided my manufacturers and designers.
IACS Secretary General, Robert Ashdown, said: “As the industry continues to adopt alternative fuels, IACS remains committed to advancing maritime safety standards. By introducing enhanced safety requirements tailored to modern engines and different fuel types, URM10 ensures that the industry remains equipped to mitigate the risk of explosions, while adapting to the introduction of sustainable fuels.”
Stakeholders are encouraged to review these changes and update their safety practices accordingly.
