Cold corrosion is a process of sulphuric acid forming on an engine cylinder’s liner walls and corroding of the liner surface. This abnormal corrosion is thus responsible for the creating of excessive wear of the liner material. This has turned out to be a real big issue when regarding most of the new engines which are now designed in manner that is compliant with the Tier II NOx regulations and Energy Efficiency Design Index (EEDI) guidelines.
In order to comply with the new regulations, engine cylinders are to operate under increased pressures along with reduced operating temperatures. This is responsible for creating conditions below the dew point which allows for water condension on the liner walls of the cylinder. This effect then manages to combine with the sulphur produced by the combustion process and thus forms sulphuric acid, which on the other hand leads to cylinder liner wear or cold corrosion.
Cold corrosion tends to be most evident in the latest of engine designs. However, it also impacts earlier engine designs that were modified for part-load or low-load operation (which is known as ‘slow steaming’, a scenario in which a certain vessel might operate as low as 10% load).
Cold corrosion is a continuous source of numerous debates and discussions within the marine industry and is a major challenge to vessel operators. In order to help operators in their battle against the effects of cold corrosion, ExxonMobil has created an educational video that offers numerous technical insights in relation to this complex challenge.
Cold Corrosion Insights
Source: ExxonMobil Marine