IACS UR M86: monitoring and safety functions for EGCS
IACS UR M86 sets bypass, control, monitoring and safety shutdown requirements for exhaust gas cleaning systems on ships contracted from 1 January 2026.
IACS Unified Requirement M86, Monitoring and Safety Functions for Exhaust Gas Cleaning (SOx) Systems, was issued new in November 2024 and is uniformly implemented by IACS member societies on ships contracted for construction on or after 1 January 2026. It is the only IACS Unified Requirement dedicated to exhaust gas cleaning systems , and it closes a gap the IMO Guidelines never addressed: MEPC.340(77) is an emissions and discharge instrument, and says almost nothing about the safety of the installation.
M86 requires a bypass arrangement so the engines can keep running with the EGCS out of service, an interlock preventing the bypass and uptake dampers being closed simultaneously, single-fault tolerance in the control system, a safety shutdown independent of control and alarm with no automatic restart, and a table of alarms and shutdowns covering exhaust temperature, differential pressure, water level, pump and blower status, valve position and chemical leakage.
The full article will set out each section with its alarm and shutdown table, the FMEA submission trigger where the control system is integrated, the cross-references to UR M81, the unmanned machinery space case, and how the requirement is applied to an existing ship on retrofit.