The International Association of Classification Societies (IACS) has released a new unified requirement for monitoring and safety functions for Exhaust Gas Cleaning Systems (M86).
Marine air pollution regulations typically require the use of low-sulfur fuel to reduce SOx gaseous emissions. The use of Exhaust Gas Cleaning Systems (EGCS) technology is generally permitted as an alternative means of compliance.
EGCS – SOx Scrubbers can be effective in complying with regulations that require the use of 0.5 percent sulfur fuel globally and 0.1 percent in Emission Control Areas (ECA). The following requirements apply to the arrangements intended for the safeguard of the ship in case of malfunction of the EGCS.
Exhaust Bypass
The EGCS bypass arrangement is to be provided in order to continue the operation of the engines. This arrangement may be omitted, provided the EGCS is designed for dry operation and the lack of the bypass arrangement does not interfere with the continuous operation of the engine. An interlock is required to prevent bypass and uptake dampers from being closed at the same time in systems with individually controlled dampers. The interlock can comprise a pressure sensor upstream of the dampers, interfaced to the EGCS safety system, opening the bypass damper in case of high back pressure.
Control and Monitoring System
Automatic control, monitoring (including washwater discharge criteria), alarm, and safety functions are to be provided for the EGCS so that operations remain within preset parameters for all fuel oil combustion unit(s) and SOx emission abatement system operating conditions. The control system for the exhaust gas cleaning system may be connected to an integrated control system or may be a standalone system. The system is to be designed such that a single fault of a component will not lead to a potentially dangerous situation for human safety and/or the vessel. An FMEA, or equivalent, demonstrating the safety system design basis is to be submitted to the classification society, when the control system is connected to an integrated control system of a vessel. For vessels with unmanned propulsion machinery space, the alarm and monitoring systems of the EGCS can be integrated in the vessel’s centralized monitoring systems.
Safety Shutdown System
The safety system is to be designed as far as is practicable to operate independently of the control and alarm systems. Requirements include:
i) Upon activation of the safety shutdown system, visual and audible alarms are to be indicated at both the local and remote control positions. Visual alarms are to include a means of indicating the parameters causing shutdown.
ii) In addition to the automatic shutdown system, manual emergency shutdown arrangements are to be provided at both the local and remote the control positions.
iii) In the event where shutdown by the safety shutdown system is activated, the restart should not occur automatically, unless after the system is manually reset.
iv) Safety shutdown is to be automatically activated for specific conditions.
Monitored Parameters
Parameters for indication, alarm, and safety functions can be found in the unified requirement.
Read the UR in full: M86 Monitoring and Safety Functions for Exhaust Gas Cleaning (SOx) Systems
