Industry Insight: Effective ECA Compliance - Why Pairing Fuels and Lubes is a Long-Game

Gianluca Marucci, global technical services director, Castrol

Following the introduction of new Emissions Control Areas (ECA) in January 2015, Gianluca Marucci, Technical Services Director at Castrol highlights the learnings from in service performance monitoring and provides insight into why there is no silver bullet for twinning lubes with a diversified cleaner fuels mix in today's operating conditions.

Several months into the new MARPOL Annex VI regulations that require ship operators to burn fuel with a maximum sulphur content of 0.1%, ship owners and operators are starting to develop knowledge on how their chosen compliance methods are performing both operationally and commercially. While scrubbers and LNG have received limited uptake due to high retrofitting costs and limited distribution infrastructure, distillates (MGO) and other customised fuels with 0.1% sulphur content have emerged as the option of choice for the majority of the industry especially due to the softening of oil prices. Although ultra-low sulphur fuels are currently the most practical means to comply, maintaining operational performance while switching fuels in service brings a raft of challenges including issues around fuel quality, compatibility and stability. To prevent downtime and premature engine wear, operators have also been looking for solutions to address lubrication challenges in tandem with fuel switching.

Prior to the introduction of the ECA areas Castrol collaborated with operators, their crew and Original Equipment Manufacturers (OEMs) in order to find the best solutions that also take into account variables such as engine type, speed and duration in ECAs, to ensure a smooth transition when pairing lubricants with 0.1% sulphur fuel. Following the implementation of the regulation, Castrol continues to work closely with operators to carry out in service performance monitoring to better understand how lubricants are performing in these new scenarios. While lubricant manufacturers and the OEMs are building up a critical mass of data, it is important that we remain flexible and responsive during this learning curve to ensure that modern two-stroke engines continue to operate reliably and safely at a range of speeds.

Pairing ultra low sulphur fuel with low BN cylinder oil

Cylinder lubricant formulations have to be carefully tailored to achieve a delicate balance between the oil's ability to neutralise the acidic by-products of combustion and minimise contribution to deposit and ash formation, which is especially required when operating with low and ultra low sulphur fuels.

A key enabler of this delicate balance is detergency; but while detergency is present in good levels in high BN lubricants, the combination of excess BN and heat can cause ash deposits that compromise engine performance if used on a prolonged basis with low sulphur fuel oil.

To avoid this issue a low BN lubricant can be used but it is essential that operators consider the quality of the lubricants' detergency as well as the base number to prevent ash and keep their engine clean and in good working order. For low BN oils this necessitates having to build back in the detergent properties using low ash (low BN) additives rather than the high ash detergents used in high BN oils.

Failure to use a low BN product with adequate detergency could result in ash deposits behind the ring and in the ring groove, which leads to loss of movement, scuffing and breakage. To prevent this, Castrol has 'built back in' the detergent properties in its low BN solution, Cyltech 40SX cylinder oil, which it is recommending to ship owners while a full picture of the impact of low sulphur fuels on lubricant selection is ascertained. Cyltech 40SX, which has been successfully used for 15 years, is approved by OEMs for application on the vast majority of vessels operating in the ECA. In addition the lubricant has a specialised formulation that provides outstanding cleanliness due to its advanced detergency properties.

Understanding ash formation

Although Castrol recommends switching to Cyltech 40SX with 0.1% sulphur fuels, initial analysis from in service performance has indicated certain circumstances where use of a 70BN and 80BN product may still work effectively. This has been largely seen when vessels are transitioning the area briefly as opposed to operating within ECAs for prolonged periods of time.

This is because, while excess BN and heat are the main cause of ash deposits, a combination of excess detergency and clean fuel combustion generated by higher BN lubricants may actually have a cleaning up effect on the ring zone. Additionally, anecdotal evidence and resulting theories suggest a correlation between vessel speed and the formation of ash deposits; the higher the speed of a vessel, the greater the load on the engine, which in turn generates high engine temperatures that could create more ash.

While in some scenarios this could build up quickly  in the context of ECA areas it may be less so as vessels typically slow down upon entry in order to reduce the usage and associated cost of more expensive, cleaner fuels. As a result, and because engines are operating at a lower temperature, it is likely that less ash will form when a vessel is operating at a low speed using a higher BN lubricant for a short period of time.

For example, Castrol has monitored a vessel with a MAN G80ME-C9.2 engine operating for 32 hours in the ECA using Castrol's CYLTECH 80AW and noted no difference in the performance of the engine pistons and an absence of harmful ash deposits. In a further example a vessel with a WÄRTSILÄ RTFLEX 96C engine operating in the ECA for 95 hours on a CYLTECH 80AW also recorded clear crown lands and ring lands. These early indications could suggest that those operating ECA transits may be able to continue using a higher BN lubricant, atlhough in the interests of mimimising the risk of premature engine wear and tear, and prior to the finalisation of a critical mass dataset, we continue to recommend Cyltech 40SX. Accordingly, Castrol has monitored the in service performance of CYLTECH 40SX for vessels operating in the ECA for the vast majority of their service hours and initial results show a MAN S60MC-C engine and Wärtsilä RTA engines operating for well in excess of 1,000 hours in the ECA with no additional ash formation.

Evolution of experience, regulation and the fuels mix 

Finding the most efficient and cost-effective way to comply with the 0.1% sulphur regulations is a continuous journey across operational, financial and legal spectrums. Although ultra-low sulphur fuels are the most practical choice for now, alternatives such as LNG or scrubbing technology are still on the horizon. And, as the global 0.5% sulphur cap is just a few years away, we envisage that there will be a greater choice of compliance options presenting their own lubrication implications. This is why it is important to continue exploring lubrication technology and the support services required as there is never a 'single fix solution' in a market of evolutionary change.

With this in mind, lubricant manufacturers, OEMs and operators have a crucial role in building a critical mass of data that will provide a robust foundation from which future recommendations can be verified to inject further confidence into lubricant application – today and tomorrow.