ES-TRIN, Article 9.09(1) and (5) - Exhaust gas after treatment systems
How the safety objective described in Article 9.09(1) of ES-TRIN can be achieved for vessels with only a single-engine propulsion system?
The arrangements mentioned under a and b of Article 9.09(5) are voluntarily not exhaustive. In other words, a bypass system is not mandatory for vessels with only a single-engine propulsion system. It is up to the national authority/inspection body to decide whether Article 9.09 is complied with for the exhaust gas after treatment system.
For Stage V engines, if the exhaust gas after treatment system becomes clogged, the engine backpressure increases and may cause the engine to increase the emissions. Alarms for aftertreatment blocking are not mandated by regulation and will vary a bit from manufacturer to manufacturer, but warnings are likely to be given by the engine manufacturers warning system before a stage V engine (consisting of the engine and exhaust gas after treatment system) is blocked to the point of shutting down the engine. When alarms are given, the engine shall not stop immediately, and the helmsman shall look for a place to repair the system as soon as possible. By means of a graded alarm for exhaust gas temperature and exhaust gas back pressure, the helmsman should be informed in a timely manner. The manufacturer could decide to alert specifically on regeneration requests, higher loads, charge, or overload of the exhaust gas after treatment system. In the event a suitable alarm system is not provided by the engine manufacturer as system could be provided by the installer.
Many manufacturers probably will automatically shut the engine down before major engine damage occurs in this event. However, in accordance with Article 8.03, it is possible that manufacturers would disable the shutdown or install an override of the manufacturer instigated shutdown, in the same way that an oil pressure shutdown must be disabled or have an override for single engine inland waterways vessels.
In other words, Article 9.09(1) is fulfilled when the timely triggering of alarms and the possible override of automatic shutdown allow the craft to continue to make steerageway under its own power, especially to quickly reach a safe location. Such a solution should be properly described in the manufacturers’ or installers’ instructions to be used by the crew.
Finally, it remains possible for a stage V engine to have a bypass as an auxiliary emission control strategy as described in 2.3.5 of Annex IV of delegated Regulation (EU) 2017/654. Indeed, the safety objectives described under Article 9.09(1) are covered by the “operational safety reasons” referred to in letter b of 2.3.5. However, the original engine manufacturer would have to include such auxiliary emission control strategy for the engine certification. The by-pass hardware may be supplied by any party provided the engine manufacturers installation instructions are followed.
CESNI/PT (21) 4 rev. 2
CESNI working group technical requirements CESNI/PT, exhaust gas after treatment systems, bypass