Procedure in case of SOx scrubber failure

Q. What is a procedure when SOx scrubber (EGCS / Exhaust Gas Cleaning System) fail ?  

A. IMO issued guidance of recommended measure for MEPC.1/Circ.883/Rev.1 (15 December 2021) 

The outline of the guidance is as follows, 

• An EGCS malfunction event should be recorded in the EGCS record book including the date and time the malfunction began, the duration of the malfunction and, if relevant, how it was resolved, the actions taken to resolve it and any necessary follow-up actions. 

• A system malfunction that cannot be rectified it regarded as a breakdown. The ship should then change over to compliant fuel oil if the EGCS cannot be put back into a compliant condition within a maximum of one hour.  

However, in the following cases, it may not be considered as a failure and you may not be required to switch to regulated oil. 

• Temporary excess of emissions in a short period of time is not considered a rule violation. However, any EGCS malfunction that lasts more than one hour or repetitive malfunctions should be reported to the Flag administration and the port state’s administration along with an explanation of the steps the ship operator is taking to address the failure. 

• In the event of a single sensor failure (emission ratio, wash water pH, etc.), if other parameters are continuing at normal levels and exhaust gas/discharging water are acceptable, then a single device rather than a system failure It is shown as a defect only and is not considered as a rule violation. 

Q. Is there a rule on the amount of compliant fuel oil that a ship should have in case of a scrubber failure?

A. There is no rule on the amount of compliant fuel oil that ship should have in case of scrubber failure.
If the ship does not have compliant fuel oil or sufficient amount of compliant fuel oil on board, a proposed course of action, in order to bunker compliant fuel oil or carry out repair works, should be communicated to relevant authorities including the ship’s Administration and relevant port state for their agreement.

Link: 
https://wwwcdn.imo.org/localresources/en/OurWork/Environment/Documents/Air%20pollution/MEPC.1-Circ.883-Rev.1.pdf