If your vessel is bunkering LSMGO in Rotterdam, then your filters may get clogged.
Statistics:
In the last One Week (12th October to 19th October 2015), at least three ships reported problems of wax formation and subsequent filter clogging. One of these three ships experienced repetitive blackouts due to clogged filters. All the three ships bunkered at Rotterdam and the product was LSMGO.
These vessels reported wax formation in both main and auxiliary engine filters leading to dangerous situation when transiting the English Channel. One vessel reported that the engine room temperature was around 12 degree Celsius and other 14 degree Celsius. The Ship Management reported the problem to Viswa Lab for technical advice and recommendations.
Weather Forecast (October 2015).
Ambient Temperature – 13 degree Celsius to 17 degree Celsius.
Sea Water Temperature – 12 degree Celsius to 16 degree Celsius.
What You Have to Know?
The cold flow properties of a fuel oil are temperature dependent and can have an adverse effect on low temperature operability. For example, at very low temperatures, one fuel may remain fluid whereas the other, of a similar grade, may either stop flowing or result in the deposition of wax crystals at the filters, causing fuel starvation and possible engine shut down.
ISO 8217 limits the cold flow properties of a fuel through setting a limit on the pour point (PP). However, given that wax crystals form at temperatures above the PP, fuels that meet the specification in terms of PP can still be a challenge for operations in colder operating zones, as the wax particles can rapidly start blocking the filters, potentially blocking them completely. The cold flow properties of a fuel can be evaluated through one of, or a combination of, the three most commonly used test methods, these being: a) cloud point, b) cold filter plugging point and c) pour point.
Cloud Point (CP)
The cloud point is defined as the temperature at which wax crystals start to visibly form in the fuel and a transparent fuel becomes cloudy (thereof the name).
Cold Filter Plugging Point (CFPP)
The cold filter plugging point is the highest temperature, expressed in multiples of 1°C, at which a given volume of fuel fails to pass through a standardized filtration device (45 micron) in a specified time (60 sec) when cooled under the conditions prescribed in the test method.
This test gives an estimate for the temperature at which a fuel will give trouble free flow in certain fuel systems.
Pour Point (PP)
The pour point is defined as the temperature at which the fuel ceases to flow, experienced as the fuel being perceived to have turned solid.
Typically, the difference between the above temperatures will be about 5‐10 degrees for untreated fuels, although higher differences are recorded, with the CP having the highest temperature and the PP the lowest.
The CP identifies the temperature at which crystals will start forming in the fuel, whereas CFPP provides a relative indication of the point where filterability problems may start to occur, leading to possible restrictions of fuel flow to the engine. Statistically it is not possible to determine the CP and CFPP from just knowing the PP figure as the correlation is very broad.
When it comes to the CFPP, recently there have been a number of cases where the differences between the CFPP and PP has been nearly 24 deg C and above; The PP was meeting specification being well below zero degrees Celsius. Ships were experiencing heavy wax deposits in the separators, restricted filters along with heavy wax deposits in the storage tanks.
Viswa Lab has tested these samples for CFPP where after the fuel was heated to a safe recommended temperature and thus the fuel was used without any further problems.
Special Notice:
If the approach of applying heat is being followed it should be ensured that the fuel is not overheated resulting in the viscosity dropping below the minimum recommendation of 2 cSt at any point in the fuel system, including the engine inlet. In order to reduce this risk, heating should be limited to max 40 deg C.
Do not hesitate to write to Viswa Lab to know more about the CFPP tests and other ways to mitigate the problem. Viswa Lab also suggests a simple on board method to determine the point at which the fuel starts to deposit waxes or becomes cloudy.
We thank Viswa Lab for sharing the story, statistics and information with us.
Did your vessel experience such problems? Please do not hesitate to share it with the Maritime World!
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