In International Shipping News 15/06/2018
Driven by the International Maritime Organization (IMO), the marine industry is currently going through important and significant environmental changes through a reduction in sulphur content of marine fuel from 3.5% to 0.5%. To fulfil this new requirement, stakeholders in the industry are debating and considering the merits of alternative fuels, different engine equipment and configurations as well as advances in scrubber cleaning technology. Fuels and lubricants both come into contact with engine systems so any changes that occur will have an even wider impact on marine vessel equipment. To minimize the impact of any negative consequences it is important to manage this change effectively.
Managing change effectively is an attitude supported in wider industry sense. Henry Mintzberg and John Kotter are change management experts and both say we must manage change and continuity simultaneously. Kotter says “What we do not do well is identify the most important hazards and opportunities early enough, formulate creative strategic initiatives nimbly enough, and implement them fast enough.”
One method to manage the effects of the Sulphur Cap is through monitoring of the in-service lubricant. Oil Condition Monitoring (OCM) utilises the science of tribology, and enables the condition of a vessel’s engines and other on-board equipment to be monitored. OCM provides an early warning system which when used in combination with fuel analytical information, helps to avoid costly engine failure and downtime and has an important role in preventive maintenance programs.
The best analogy is that of a blood test taken by your doctor to identify, predict and help combat on any potential health issues.
During the combustion cycle, Sulphur in the fuel is released forming SO2 (Sulphur Dioxide) and some of this forms SO3 (Sulphur Trioxide). Water contained within the scavenging air and from the combustion process reacts to form Sulphuric Acid. It is important, therefore, to monitor and control any negative and potentially damaging effects of acidity and alkalinity.
In built mechanisms in the form of oil additives are designed to improve the lubricant performance of the base oil. The choice of additives is determined by the specific application. For the 2020 change, alkalinity additives (like Calcium Carbonate) will be useful to combat oil acidity.
Why Alkalinity Additives? Most modern two stroke engines have been designed for operation on high Sulphur residual fuel.
Consequently the cylinder oil used will have a high base number (BN). If the acid is not neutralized, corrosion of iron will occur and this is the primary cause of corrosive wear for liners and piston rings. Conversely a vessel using low and ultra-low sulphur fuel will produce less sulphuric acid during the combustion process. If the BN of your cylinder oil is too high this may mean that the oil is too alkaline and then compounds can be formed which may cause damage. Some slow speed engines suffer from alkaline deposits building up on the piston crown which can damage the oil film between the piston ring and liner. This can lead to scuffing and seizures. Deposits may also form between the piston rings and pistons, preventing free movement of piston rings and increased liner wear.
Why is OCM important then? Degradation of the oil occurs over time as these protective additives are consumed and engine breakdown products build up. It is important that these changes are monitored and acted on.
Total Base Number (TBN) in a marine oil generally ranges from approximately 15-80mgKOH/g and is analyzed by Potentiometric Determination (Test method: ASTM D4739). This method, for used oil, uses a less polar solvent and weaker titrant than the fresh oil version. The sample is dissolved in a solvent mixture and then titrated with standardized hydrochloric acid. The end point (inflection point on a titration curve) is detected by a change in potential of an electrode connected to a voltmeter/potentiometer and is reported in milligrams of potassium hydroxide equivalent per gram of sample (mg of KOH/g).
All OCM data from the lab (not just TBN) is compared to what is known about the equipment and the lubricant.
The following table shows a range of OCM laboratory tests and their relevance;
The following table shows a range of OCM laboratory tests and their relevance;
The data is trended graphically over time and displayed in sections on lubricant and additives (oil condition monitoring) and wear and contaminants (equipment condition monitoring). An excerpt from a recent report is given below:
Typically, the higher the BN, the more acid it will be able to neutralize. As the oil becomes contaminated with acids the base number will drop.
Expert independent advice is provided using CIMAC guidelines (from the International Council on Combustion Engines) as well as a simple summary using easy to read icons for Satisfactory, Caution and Action.
In conclusion, we remember Henry Mintzberg’s and John Kotter’s approach that we must manage change and continuity simultaneously. Participating in an established lube oil testing program can help vessel operators to manage operational risk, comply with 2020 legislation and optimize costs during these changing times. For this to happen it is important that you partner with an experienced and informed supplier that can help monitor this change and provide impartial fuel and lubricant advice. Veritas Petroleum Services has an important role in OCM and Fuel Testing preventive maintenance programs. Our Rotterdam Laboratory has the very latest analytical technology, automation and robotics for the testing of lubricants and fuels.
Source: Veritas Petroleum Services Group
