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Thursday, February 6, 2020 

A small study undertaken by DNV GL among shipowners suggests that corrosion and sensor failures are on top of the list of issues with exhaust gas cleaning systems, mainly due to choosing a wrong material or coating and neglecting maintenance intervals.

Dr Fabian Kock, Head of Environmental Certification, DNV GL - Maritime, said that choosing the right material and coatings to avoid corrosion of the piping is essential. GRE pipes with a diameter of up to 1m need supporting struts to avoid damage when litres of heavy wash water flushes through them. "Because of reported issues of leakage and corrosion of overboard pipes, DNV GL has updated its rules and requires annual thickness measurements on various overboard pipes and spool piece designs," he said.

"Sensor failures are also a big concern, and adhering to planned maintenance intervals is of utmost importance. When a sensor fails, the control system can get the wrong data and cause an incorrect or unnecessary operational response. Misleading sensor data can also falsely suggest that emissions are within limits and only when the emissions are checked by an authority will this be detected. In that case, the operator may get a penalty in the form of a high fine; in some ports the responsible officer might even be arrested," said Dr Kock.

Some EU and Chinese ports have fitted sensors at the quayside, and on some occasions, Port State Control officers equipped with a handheld sensor have boarded to check emissions. Drones may be used in some areas to measure vessel emissions.

"Adherence to the planned maintenance intervals and concluding a service agreement with the sensor manufacturer helps a lot. Keeping spare parts on board is also vital to avoid prolonged scrubber outages. Furthermore, a preliminary test of the control system can help avoid failure during operation as well as costly repairs or reinstallations. DNV GL already offers hardware-in-the-loop testing for these control systems at the workshop to check how the control system behaves in various situations and extreme conditions, such as very low or high temperatures, which can be simulated during these tests as well," said Dr Kock.

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