ABS issued regulaory advice 08/2025 to maritime industry on OWS issues which has led to PSC detention. This notice details recent Port State Control (PSC) detentions relating to the operation of Oily Water Separator/Oil Content Meter (OCM) and current discussions being held at the IMO for the provision of a flow switch on the effluent sampling line.

The advisory highlights two very key point related to Oily Water Separator as below 1. Valves in the sampling water line supplying the content meter of Oily Water Separator may cause PSC DETENTION. 2. Oily Water Separator sampling point shall be installed in a vertical effluent pipe.

Two PSC detention case is described with relevant provision of Marpol, giving the reason of detention, detailed regulary framework regulation and ABS own recommendation. The two cases discussed are related to Sampling Line and Sampling Point.

Sampling line issue is related to MEPC requirment of response time for alarm and overboard valve to shut, the manula valve in the sampling line may bypass this MEPC requirment. ABS recommends that “Until amendments are made to the MEPC.107(49), owners check their OWS system(s). If a valve is fitted in the sampling line, this valve shold be removed. This would safeguard the system operation in accordance with MEPC.107(49).”

Sampling Point issue relates to the location of it in the OWS system which led to PSC detention. As per MEPC.107(49) Chapter 6.1.1, Installation Requirements, states that “For future inspection purposes on board ship, a sampling point should be provided in a vertical section of the water effluent piping as close as is practicable to the 15ppm bilge separator outlet.” There have been several cases where ships have been detained for not complying with this requirement.

ABS Recommends “Ship owners or operators are invited to review the insights provided in this letter and ensure that the sampling point is connected to a vertical section of the water effluent piping as close as is practicable to the 15 ppm Bilge Separator outlet.”

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