Coast Guard issues notice on scrubber SOx alarms

The following is a memorandum from the U.S. Coast Guard:

(WASHINGTON) — The purpose of this field notice is to provide Coast Guard expectations for dealing with alarms from exhaust gas cleaning systems (EGCSs), where such alarms are triggered by short-term temporary emission exceedances due to predictable operations of vessels. This notice is intended for vessels operating in the U.S. portion of the North American Emission Control Area (ECA) and the U.S. Caribbean Sea ECA, pending consideration of reference (a) at the International Maritime Organization (IMO).

As noted in reference (a), the United States does not consider short-term temporary SOx emissions that exceed the acceptable limits while in ECAs, due to predictable operations, such as engine load changes, to be noncompliance events. The United States recommended that reference (b) be amended to address temporary short-term exceedances by specifying the conditions under which they would not be deemed to be violations of reference (c) fuel sulfur requirements.

Although the IMO has not taken final action on these recommendations, it agreed to refer an output to its Pollution Prevention and Response Subcommittee to review reference (b). Until IMO acts on this issue, owners and operators of vessels with continuous emissions monitoring systems (Scheme B in reference (b)) can address issues raised by these occurrences by having the scrubber manufacturer identify, in the scrubber manual, the manufacturer’s solutions to these issues. Owners and operators of such vessels can also address the issues in the ship’s safety management system (SMS).

The scrubber manual and SMS system should address the following issues. The manual or SMS system should identify the temporary exceedance that may be expected to occur under specific operating conditions and the length of time each exceedance would be expected to continue. The manual or SMS system should also clarify the maximum amount of time that would be considered to be a short-term temporary exceedance before the vessel would need to switch over to compliant fuel.

In anticipation of U.S. Port State Control enforcement of MARPOL Annex VI, vessel representatives for vessels fitted with EGCSs should clarify the procedures to be taken in response to these conditions through their SMS. Specifically, the SMS should reference the manufacturer’s guide, address approved short term instances when the EGCS alarms may sound, and how, when, and where to document these short term instances. The SMS should also have instructions regarding notification when the emissions exceed the allowable SOx limit for a period that is longer than a short term instance. Specific examples with time ranges should be addressed in the SMS, along with procedures to commence corrective action. Port State Control examiners may review these procedures during the course of a normal exam and verify that these instances were documented and that appropriate actions were taken.

Although reference (b) does not contain requirements to report a temporary, short term SOx exceedance, an EGCS failure which meets the criteria for a marine casualty, as clarified in Navigation and Vessel Inspection Circular (NVIC) 01-15, should be reported as required.

If you have any questions regarding this notice, contact the national technical adviser at (954) 767-8021, or via e-mail at, or the Office of Commercial Vessel Compliance, Foreign and Offshore Compliance Division at

By Professional Mariner Staff