Precise lubricant questions need broad answer
Feb 17, 2016
New rules covering ship emissions have driven two-stroke engine design over the last 15 years, but changing market conditions have complicated the outcome for engines in operation. Shell Marine Products has responded with an intense programme of marine lubricant innovation
With only fuels of up to 0.1% sulphur content now allowed inside Emissions Control Areas from 2015, HFO with up to 3.5% content will be allowed elsewhere until at least 2020. Beyond 2020, shipowners face uncertainty: an IMO review in 2018 will determine global regulation, but the European Union has said it will further limit sulphur fuel content from 2020 regardless.
At the same time, the need to develop ship engines for lower sulphur content HFO and new fuel types coincided with years of oil inflation that caused owners to cut operating speeds for the bulk of their existing tonnage. Despite recent falls in oil prices, engines fed by HFO continue to run predominantly at part-loads that expose vulnerability to cold corrosion.
Jan Toschka, General Manager, Shell Marine Products explains that the considered response to these variables from the cylinder oil development perspective has been a portfolio of lubricants for two-stroke engines broad enough to accommodate different imperatives.
“The cost and reliability of vessel operations can be affected by changes to a number of different factors,” says Toschka. “These include fuel sulphur content, but also climatic conditions such as high humidity, liner wall temperatures, and engine load influences such as hull fouling and propeller efficiency, changes to engine settings and operating conditions.”
“In a changing regulatory landscape, SMP has invested in a broad range of cylinder oils for two stroke engines. SMP now offers Alexia 50, Alexia S3, Alexia S4, Alexia S5 and Alexia S6 cylinder oils, with base numbers ranging from 25BN to 100BN to take account of different fuel sulphur contents, vessel operating profiles and engine loads.”
For use in ECAs, SMP launched Shell Alexia S3 in September 2014 - a 25BN cylinder oil for use with low sulphur and distillate fuels up to 0.1% sulphur content. Shell Alexia S3 has secured Letters of No Objection for use from both MAN Diesel & Turbo and Wärtsilä.
“Shell Alexia S3 is now available in over 330 ports in 20 countries,” Toschka says. “It is aligned with the ethos behind the entire Alexia portfolio – finding a solution that helps peace of mind for the customer by being designed to deliver the right cylinder oil in the right place, at the right time.”
For use outside ECAs, SMP offers a range of oils for different vessel operating profiles including slow steaming. Shell Alexia S5, for example, is an 80BN Cylinder oil for two-stroke low-speed engines running under conditions of high oil stress and burning residual fuel with Sulphur levels up to 3.5%. Meanwhile, S6 is a 100BN oil recommended for fuel sulphur levels up to 3.5%, under conditions of extreme oil stress.
Efficiency is not simply a matter of matching BN to sulphur content and then optimising feed-rates. Cylinder oil in two-stroke engines is exposed to acid, thermal, insolubles and humidity stress. An imbalance between the acid stress and a cylinder oil’s BN, for example, can lead to excessive deposits on piston top lands, rings, and ring grooves, leading to scuffing and cylinder liner damage. This can lead to higher maintenance costs and reduced vessel availability.
“Of course, our reputation is built around our supply of reliable lubricants, but ship owners also rely on our delivery of technical service solutions”, states Toschka. “In demanding commercial conditions, many low-speed two-stroke engine operators have decided to reduce feed rates to minimize lubricant costs, but there is a fine balance to be struck between cutting costs and having a negative impact on engine reliability.”
To enable the correct balance, SMP offers Shell Lube Monitor - a cylinder condition monitoring program that helps weigh up specific combinations of lubricants, fuels and the severity of operational demands on the engine, as well as specific operational and maintenance requirements. It can include a feed-rate optimization and wear monitoring service, allowing ship operators to develop strategies to help maximize operations while maintaining high levels of service reliability.
It also offers cylinder drain oil analysis, expert advice, support and implementation tools and an annual report quantifying the benefits achieved. Finally, customers receiving Shell Lube Monitor services can expect maintenance reviews and guidance.
Shell Rapid Lubricants Onboard Plus, meanwhile, is an onboard test kit that provides ship’s engineers with an on-the-spot method of testing the condition of the lubricants on the vessel. This includes the capability to measure Total Base Number (TBN) and water levels onboard.
These onboard services are backed up by Shell Rapid Lubricants Analysis, which provides laboratory-based oil condition monitoring. This is a service that is in effect an early warning system which aims to give peace of mind that equipment and lubricants are in good working order.
“Shipowners and operators are as focused on fuel prices as they have always been, but new cylinder oils have been required at a time when wear rates and equipment protection are under unprecedented scrutiny. Today, customers want precise answers on wear rates and sulphur neutralisation, on feed rates, thermal stresses and acid stresses. Of course, they have always needed to know that they were not spending too much on lubes, only now the conversation is not about the cost of the product alone, but about the total cost of ownership.”