NEWS ANALYSIS


Lubricating the engines of trade


manufacturers offering polarised advice, writes Julian Macqueen. Te use of low-sulphur fuel in Emissions Control


R


Areas (ECAs), and the advent of slow-steaming to stave off the rising cost of fuel, have seen Castrol Marine and Total’s Lubmarine come up with opposing market solutions. Castrol Marine proposes a range of cylinder oils


“in order to enable a ship to operate most efficiently, taking into account its fuel sulphur content, engine power and cylinder oil feed rate”. Total, in the opposite corner, claims its Talusia


Universal (TU) lubricant “combines the performances of both a high base number [BN] and a low BN whatever the sulphur content”. But, one expert says that the arrival of slow


steaming has made the job of the marine lubricant manufacturers that much harder. Danny Shorten, lead business development


specialist: Condition Monitoring at Lloyd’s Register and a member of


the International Council on


Combustion Engines’ (CIMAC) working group on marine lubricants, says that slow steaming has tipped the balance on lubricant performance for two-stroke engines. “In slow steaming, as the residence time of the oil


on the liner surface is increased, there is a greater potential for neutralisation demand and enhanced corrosion control,” he says. “It is argued that a higher base number material


may be required to manage acidic build up, as, under low load operations, the time between oil injections, and thus residence time on the liner, is increased.” Castrol argues that more neutralisation of acidity


is required in deep sea operations [eg while slow steaming], therefore, making the case for a higher base number (it suggests 80BN). Total’s product, on the other hand, has a base


number of around 57BN and uses a slightly different chemistry which, it says, increases the neutralising capability of the material. Te science behind both arguments is not in doubt,


but what has raised Castrol’s hackles is Total’s claim that TU can be used in all two-stroke engines whether in an ECA or not. For Shorten, such a claim given the added


complexity that slow steaming brings to the issue can only highlight the need for “unambiguous guidance and support”.


12


egulatory and commercial pressures are changing the demands made on marine lubes used in two-stroke engines, with lubricant


“Oil maintains a fluid film on the surface of


the cylinder liner for longer under slow steaming conditions and, therefore, has to neutralise more.” And he adds that evidence from the first quarter’s


FOBAS fuel testing reveals an increase in the average sulphur content per bunker thus making the need for clear guidance even more poignant. Castrol argues that a generic product is fine until


slow steaming increases the demand per unit on the lubricant but, equally, the Total argument is not just about the amount of the base number; it is also about efficiency. “Why shouldn’t a more efficient base number


system do the same job as a higher base number that is less effective?” says Dr Holgar Gehring, chair of the same CIMAC working group. According to Gehring, a single solution for all the


cylinder applications “seems like a good approach”, but he adds that “it


is too early to formulate a


definitive answer” to that question. Te debate is not just about chemistry as marine


lubricant manufacturers have found themselves having to operate in a very different market. In the pre-ECA days, the industry used higher


sulphur fuel oil for which a base number of 70 or 80 was a “perfect solution”, says Gehring. But, ECAs ushered in a new era where two-stroke engines were operating on low sulphur fuel


longer periods of time. Te first problems to emerge included excessive ash build up in the cylinder liner. One theory pointed to the too high base number, and the absence of corrosion on the cylinder liner. “Corrosion generates a micro structure,” he


explains. If the surface is too smooth for oil adhesion then piston seizure could result. As a first step, some oil companies lowered the


base number from 70 to 40, but this was not sufficient because “the base number in marine lubricant is a neutraliser and a detergent”. And Gehring points out that current technology combines a lower base number with a higher detergent capability comparable to a 70BN lube. Te global marine lubricant market is estimated


at US$5.7 billion, according to consultant Power Systems Research. And while Castrol and Total’s products both have their strengths and weaknesses, it would seem that an answer to the low sulphur fuel/ slow steaming conundrum is still some way off. Te companies may be pushing hard to be the solution the market wants but in the meantime, establishing the best feed rate through routine engine monitoring would seem to be good advice. NA


The Naval Architect May 2012


for


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60  |  Page 61  |  Page 62  |  Page 63  |  Page 64  |  Page 65  |  Page 66  |  Page 67  |  Page 68  |  Page 69  |  Page 70  |  Page 71  |  Page 72  |  Page 73  |  Page 74  |  Page 75  |  Page 76  |  Page 77  |  Page 78  |  Page 79  |  Page 80