A device fitted in the exhaust line that removes sulfur oxides from engine gases, allowing use of high-sulfur HFO under IMO 2020.
Quick facts
Regulation
MARPOL Annex VI
In practice
Open-loop scrubbers discharge wash water overboard, and their wash water must meet pH, PAH, turbidity, and nitrate criteria. Some port states and regional authorities — including those in certain Baltic, North Sea, and Chinese ports — prohibit open-loop discharge in their waters, requiring operators to switch to closed-loop mode or to compliant low-sulphur fuel. Engineers must log scrubber operating parameters, wash water quality, and any system bypass events in a dedicated EGC Record Book, which port state control officers inspect alongside the Bunker Delivery Notes.
Regulatory detail & full definition
An Exhaust Gas Cleaning System — commonly called a scrubber — is fitted in the exhaust uptake of a marine engine or boiler to wash sulphur dioxide from combustion gases using seawater or treated fresh water. By removing SOx to the equivalent of burning 0.50% or 0.10% sulphur fuel, an approved scrubber allows the vessel to continue burning high-sulphur HFO while complying with MARPOL Annex VI Regulation 14 sulphur limits. IMO guidelines for EGCS are contained in MEPC.259(68) and subsequent resolutions, covering both open-loop (seawater discharge), closed-loop (recirculating), and hybrid systems.
Open-loop scrubbers discharge wash water overboard, and their wash water must meet pH, PAH, turbidity, and nitrate criteria. Some port states and regional authorities — including those in certain Baltic, North Sea, and Chinese ports — prohibit open-loop discharge in their waters, requiring operators to switch to closed-loop mode or to compliant low-sulphur fuel. Engineers must log scrubber operating parameters, wash water quality, and any system bypass events in a dedicated EGC Record Book, which port state control officers inspect alongside the Bunker Delivery Notes.