Analysis, collaboration and managing complexity are key when it comes to the increasing problem of cylinder liner corrosive wear
These were some of the main takeaways from Riviera Maritime Media’s webinar, Marine lubrication for ULSFO, VLSFO and safeguarding engines, held on 7 June 2021 during Riviera’s Marine Lubricants webinar week.
The panellists were Gulf Oil Marine technology and innovation director Don Gregory, Shell Marine senior lubricant technical advisor Dirk Hoek, Delta Corp Shipping senior vice president shipmanagement Caroline Huot and VPS Group OCM business development leader Paul Parkinson.
The cost of a main engine claim can be as much as US$645,000 according to insurer the Swedish Club, while main engine damage represented 34% of all claims in 2018 – and IMO 2020 and Covid-19 could increase this.
Mr Parkinson presented these figures and commented “an OCM can help minimise the chances of becoming part of these statistics. The main function of lubricants is to reduce friction and any wear and cool, absorb and clean. Oil additives improve lubricants’ performance.”
Focusing on the corrosive wear of cylinder liners, Mr Parkinson highlighted the importance of the base number and the serious risk of corrosive wear of cylinder liners, piston rings and bearings. “Sulphur in corrosive sulphuric acid originates from fuel and the 0.5% cap caused a significant increase in the use of VLSFO between 2019 to 2021.”
He explained that VPS uses a simple traffic system to show a satisfactory situation or a critical situation. Its statistics show that in 2019, before the change, over 50% of oil samples were fine, 34% were at the warning stage and 11.1% were critical. Cylinder-related problems accounted for 13.2% from the amber total and for 14% of those in the red. Fast forward to 2021 and 40.3% of amber cases were due to cylinder-related problems and 41.4% from those in the red.
VPS took a case study to investigate the impact of rising iron on the wear of the cylinder in 2020 and the importance of the base number to protect against sulphuric acid. At the start of the incident, the iron content in all five units was elevated and after the incident there was a significant spike in iron. This indicates abnormal wear, said Mr Parkinson. The base number started at marginally above a new oil value but after the incident, a very high base number of 132 was observed on unit five, which also had 9,898 parts per million – the highest level of iron of the five units.
VPS identified multiple cases of reddish or white-coloured deposits forming on the underside of cylinder heads linked to excessive wear on cylinder liners and broken piston rings. “The deposits were so hard they were scraped off using power tools,” said Mr Parkinson.
“The deposits were analysed and showed they were mainly formed of calcium, so we propose this came from reserve alkalinity in cylinder oil. The increase in the iron content indicates abnormal wear of units and the replacements to six liners, piston rings and pistons came to US$200,000.”
Mr Parkinson recommended actions to prevent this from occurring, including selecting the correct cylinder oil in relation to fuel choice, performing regular sampling and analysis, and fuel testing regarding the combustion monitor engine operations during changeover.
Meanwhile, Mr Hoek emphasised the importance of physical inspections to optimise cylinder conditions and the feedrate post IMO 2020. He said the feedrate should be below 1.0. He warns, “If 1.2/1.3 grams per kilowatt hours seem necessary to get deposits under control go for another cylinder lubricant – that is the important advice we are giving.”
He said when the company starts its monitoring, it wants crew to do cylinder drain oil testing and to submit lab samples. “We advise on getting the feedrate as low as possible to between 0.6 and 1.0.”
Ms Huot gave an operational perspective on post-2020. “The challenge even more than before is to match the cylinder oil grade and fuel type.” A reflection on procurement strategy is key to avoiding compatibility issues post-2020. “Complexity was already there as soon as the new engine designs to reduce emissions and obtain fuel economy were introduced – complexity in lubrication and the handling of cylinder oil became the rule of the game. There are two factors that put most owners between a rock and hard place: cold corrosion and the need to control iron and BN (base number) and on the other hand with very low sulphur oil, the need for engine cleanliness and avoidance of deposit.”
Ms Huot said operational feedback on the most common issues includes: liner polishing and scuffing, adhesive wear on the cylinder liner, lacquering and increased lube oil consumption when operating on LSMGO and wax particles blocking filters, pipes and other equipment at low temperature (distillates).
Explaining how to achieve optimal oil management post 2020, Ms Huot said following OEM service letters was key. Other ways include regular drain oil analysis and a focus on maintenance (fuel oil cleaning and the purifier). To reduce the risk, alternate between high- and low-BN cylinder oil.
Mr Gregory highlighted the role of the CIMAC Lubricants Working Group within the area of marine cylinder oil challenges and developments. The group “brings together a wide range of knowledge in all aspect of lubrication,” he said, as well as sharing knowledge, developing information, papers and documents and providing support and direction for diesel engine lubricants. Current work includes: drawing from the user feedback questionnaire on engine problems, deposit causes and control sub group, used oil analysis, gas lubrication guidelines, scuffing and safety.
Mr Gregory said “The sub-group working on deposits has called in the OEMs to provide information on what they think the issues are on marine cylinder lubricants and what we need to understand about those to develop the paper the group is working on.” MAN Energy Solutions and WinGD reported issues including: solid compounds depositing in exhaust gas aftertreatment systems, some uncertainty around base oil performance and dual-fuel engines prone to rapid fouling, with the frequency of challenges increasing but the time to resolve them decreasing.
The sub-group also received feedback from additive companies.
Mr Gregory explained “The sub-group is looking at the feedback we are getting holistically – looking at where the deposits occur and what they are – and from that, how they can be tackled and managed.”
He said the sub-group wants to hear about operational problems from users. “The more we can get, the more useful it will be for this activity,” he said. It is hoped the paper will be issued in 2022 to ship engineers.
Highlighting key takeaways, Ms Huot said “Mastering the complexity that came post-2020 is a critical focus. It is a combination of tools – not one is sufficient, but all combined together may ensure smooth operations. Focus on fuel procurement, quality and management and focus on trend monitoring... the use of cylinder oil is important, it is not a commodity.”
Meanwhile, Mr Parkison said “For me the thing that comes through is that there is a problem, and it is complex and it is challenging. We need to first of all recognise that it is not straightforward, and the second takeaway is the importance of analysis... thirdly, it is important we all collaborate so we can deal with situation. The challenges seem to change quite quickly and the timeframe is moving, so we need to all work together and CIMAC is a good channel.”
Mr Hoek said, “As an operator you cannot select your fuel, it is not in your control, but cylinder oil selection and feedrate is in your control and I encourage every operator to get cylinder drain oil samples and inspect results.”
Mr Gregory said his key conclusions were “measure, respond and manage complexity. We need to measure lubricant conditions, look at the condition of piston rings and the piston, so frequent inspection and taking photos is an excellent way to monitor. Then you need to respond to those results. You need to have the right feedrate.
Complexity and how this is managed will be a continuing issue and will become a bigger issue with the variety of more fuels coming on board... this will require all operators to consider how they manage cylinder oil portfolio and operations.”
A poll among webinar attendees asked: are cylinder oils a commodity or a highly specialised component of reliable engine operation? The majority (80%) agreed that they are a highly specialised component of reliable engine operation. Just 20% said they are a commodity.
Asked: do you agree with oil companies who say that cylinder oil represents approximately 65% of lubricant budget on board the ship, 81% agreed, with 14% arguing that no, it is significantly more. 5% said no, it is significantly yes.
When asked: during IMO 2020 did your company have... 51% said they had problems originating from fuel and oil, 30% said they had problems originating from fuel and 17% said they had very few related problems. Just 2% said they had problems only originating from oil.
The poll question: does your company use an OCM, the majority, 55%, said regularly followed by 27% saying not at all. 18% said occasionally.