Time is rapidly running out for owners to decide on a 2020 compliancy strategy whether it mean switching to a compliant fuel or installing a scrubber. Only a small number of ships fitted with dual-fuel engines and a gas fuel storage and delivery system on board will have the luxury of comparing the relative costs and availability of different fuel types before making a choice between oil and gas fuels. For most ships, the only available option would appear to be using a compliant fuel and hoping that any increase in cost can be passed on to cargo interests.
But as marine lubricant suppliers are keen to point out, lubrication must not be overlooked and is a critical part of the switch. That is especially true for low-speed two stroke engines where matching cylinder oil to fuel is essential for both economy and efficiency. Making a mistake with lubricant type or feed rate could be expensive in terms of running cost let alone damage or downtime.
Some lubricant manufacturers have been developing new products for the new range of compliant fuels for some time and most are confident that they have a sufficient range of products to suit all fuel types expected to be available. Where the new fuels are available, most of the leading makers will have performed tests using their lubricants with fuels from as many suppliers as possible.
Chevron has a developed a range of five new cylinder lubricants in its Taro Ultra range with a BN spread between 25 and 140. At the core of the new product formulation is Taro Ultra 40, a 40 BN cylinder lubricant which will meet a majority of compliant fuel uses. Tested using some of the latest 0.5% S fuel blends its designed to provide the flexibility to be used in ECA regions with intermittent use with 0.1% S fuels as well as distillate products.
Even if a strategy is in place to use one of the new ULSFO compliant fuels, it should be borne in mind that there may be occasions when compliant fuels are not available – especially in the early days after the new requirement comes into force. This may affect vessels operating in the spot market and away from major bunkering hubs most.
It may be the case that such ships are obliged to take on fuel that is in excess of the allowed 0.5% sulphur limit. If that happens and the ship is one with a low-speed two stroke engine that requires cylinder lubricant as well as system oil, there needs to be a supply of lubes on board with a high enough BN to match the actual sulphur content or a plan to increase feed rates sufficiently to minimise the corrosive impact of a high sulphur fuel.
For ships planning to operate with scrubbers, the position is somewhat similar though likely to be easier to manage. In their case, the lubricants expected to be used most on board will be products with high BNs to cope with the increased sulphur levels in the fuel. But – as looks likely – if scrubber use is restricted in some areas, then the fuel being used will need to be compliant and either 0.5% or 0.1% sulphur content depending on whether the vessel is in an ECA or not must be used. The majority of vessels using scrubbers would still be transiting ECAs from time to time so would be likely to already have a low BN lubricant on board. If not running a low sulphur fuel with a high BN lubricant would be permissible for a short period though isn’t encouraged longer term leading to a build up of deposits. So, unless the restriction is very short in terms or time or distance allowing for a change in feed rate, a low BN lubricant would be needed.
Using a lube oil with a low BN and a high sulphur fuel is to be avoided at all costs, will inevitably lead to severe corrosion of rings and liners in a short period. Conversely, a combination of low sulphur fuel and high BN lube will likely lead to ash deposits on piston crowns and top lands but can be tolerated for short periods if necessary.
Crews on ships which are already operating with dual-fuel two-stroke engines will almost certainly be quite familiar with the types of lubricant best suited to different fuel types. For crews on newbuildings and on the ships that were built as ‘LNG Ready’ and which are being fitted with LNG fuel systems as well as the few ships which will be converted to LNG, there will be a learning curve that will have to be followed.
Since prudent shipowners will already be making plans for cleaning fuel tanks, replacing non-compliant fuel with compliant ones, they should also me looking at the stocks of lubricants needed on board possibly maintaining a lower stock than normal in preparation for 2020. Preparing for the changeover to new fuels should also involve some investigation into what an appropriate lubricant would be and their availability at ports within the vessels usual trading area.
Chevron advises that once the 2020 regulations come into play, changes to the bunker supply chain will take effect. This will possibly result in HSFO blends bunkered for use by vessels equipped with scrubber technology potentially operating continuously on a higher sulphur content than 3.5% m/m and experiencing more severe corrosion issues.
Therefore, continued HSFO use does not necessarily mean continued use of current cylinder oil products without further consideration. If a HSFO with a higher sulphur content than that currently bunkered is used there is a risk of an increased corrosive regime occurring in the engine unless there is an increase the cylinder oil BN or the feed rates. There is significant risk associated with using a too low BN cylinder oil with a high sulphur content fuel. If the BN level of the lubricant is too low and the feed rate is not optimised, then an engine will be experiencing severe corrosive wear. Optimising feed rate is essential for any ship changing fuels or cylinder oil lubricants. It is not always possible to operate an engine at or close to the OEM’s minimum feed rate without entering a corrosive regime, although this may be overcome with a move to a higher BN cylinder lubricant providing additional neutralisation and enabling the engine to operate on an optimised feed rate. This can often not only reduce engine wear, but also reduce the overall cost of operation.
Over-lubrication can also have a detrimental effect, not only in cost but also impacting liner surface condition and reducing the oil film effectiveness. In ships continuing to burn HSFO or moving to a compliant fuel, used oil analysis should always be conducted to ascertain the optimal feed rate to minimise corrosive and abrasive wear. If corrosion does start to occur, then a switch to a higher BN or a feed rate adjustment may be required.
For intermittent operations that vary between the use of LSFO, blends and distillates when voyaging between the open ocean and emission control areas, the use of a 40 BN single grade product is recommended by Chevron Marine Lubricants. This removes the use of multiple cylinder oils, reducing on-board complexity.
Lubricant analysis services such as those offered by Chevron with their DOT.FAST drip oil analysis program and other lubricant suppliers, are regularly used by the larger ship operators and to a lesser degree by operators of older vessels. Even so the multiple permutations of lubricant and fuels that will exist after 2020 should provide an incentive to operators to avail themselves of such services at least until a bank of knowledge and experience is built up. On board ship regular visual inspections whenever operations permit will complement oil analysis services.
Some services such as DOT.FAST allow for data on total iron content and residual BN to be taken on board and transferred ashore for further interpretation. These services will provide a much quicker result that systems whereby samples are sent to laboratories for analysis.
There will no doubt be plenty of advice disseminated by fuel suppliers and lubricant manufacturers and also by OEMs and P&I clubs and H&M insurers. Superintendents should gather as much of this as possible and pass it on to engineering staff on the ship, once they are satisfied of its applicability. Ensuring that may mean checking with OEMs and lubricant suppliers as the wrong advice can be as troublesome as the wrong choice of lubricant.