FAQ – MARINE LUBRICANTS
- Lubrication – Provide a film between moving parts.
- Cooling – Heat transfer media.
- Sealing – Filling in uneven surfaces
- Cleaning – Holding contaminants in suspension.
- Dampening & Cushioning – Of components under high stress.
- Protection – From oxidation & corrosion
Lubricants are miscible if they use the same base oil type such as, for example, mineral base oils. They are not miscible when base oils are of different type, e.g. synthetic and mineral base oils.
The service life or the change interval of a lubricant is generally determined by the OEM. The OEM may define the change interval as a defined duration based on time or equipment running hours. They also may define minimum/maximum oil parameters that are determined by oil analysis. Please refer to the equipment manual, service guidelines, or directly to the OEM for these recommendations.
Each equipment is requiring a particular type of lubricant because of its mechanical configuration and its operating condition. The reliability of the equipment is the goal to achieve for the lubricant. It definitively depends upon the operating pressure and temperature, the mechanical stress, the frequency of use and various other parameters depending on the environment.
Synthetic lubricants are lubricants formulated with base oil coming from advance chemical industry like Esthers, PAO (Poly Alpha Olephine) – those synthetic base oils replace the mineral base oils from the crude oil in the formulation and have better performance.
EAL are lubricants with smaller impact on the environment if they are discharged involuntary into the sea or in nature in general. EAL are biodegradable, no bioaccumulate and not harmful for aquatic environment.
Emission control areas have different naming depending on the regulator who define them. They are generally called ECA. However, the rules to apply when sailing in ECA can change from one area to another because the regulator is different, e.g. the IMO (International Maritime Organization) or the local governments. ECA are located along the coasts on a distance that can reach 200 nautical miles or are defined on a particular geographical area. The current ECA are located in Northern Europe, along the American coasts (including American Islands and Territories), and in the estuaries of the great Chinese rivers.
Currently in the European ECA vessels must use distillate fuels with less than 0,10% of sulfur. In the American ECA the rule is the same but the vessels must also achieve the Tier III stage for NOx emissions (Nitrogen Oxides). On top of that vessels much show they are using EAL when calling American ports. In the regulated zones of China, it is scheduled to decrease the sulfur content of the fuel from 0,5% now to 0,1% in 2020.
Cylinder Oils with BN of 15 up to 25 and 40 are the two types of cylinder lubricants for 2 stroke engines available according to the recommendations of the OEM. However, cylinder oils with 40 BN were designed to be used for low sulfur HFO operation. Thence it is better to select cylinder oils with BN from 15-25; depending on the brand of your choice for the most modern engines running on ECA compliant fuels.
Cold corrosion is an abnormal corrosion accompanied by a drop in engine temperature, which allows acid to build up on the cylinder liner. Exhaust systems suffer from cold corrosion due to acid formation from combustion process of the engine. It produces sulfuric acid which leads to excessive liner wear, requiring expensive replacement.
Cold corrosion is not only serious in the latest engine designs but also it has impacts on earlier engine designs modified for part-load or low-load operation. The design modifications included:
Variable turbo charger nozzle rings fitted
Engine tuning changes
Exhaust gas bypass valve fitted
Modifications did not provide cure for this corrosion to the engine. Some become mildly corrosive and others also remain potential to affect seriously.
The engine cylinders, in most recent engine designs, must operate under higher pressures and lower operating temperatures. It creates enabling conditions allows water to condense on the cylinder liner walls and form sulfuric acid with combining products from combustion process of engine. This ultimately leads to cold corrosion.
n case of corrosion the first action to take is to increase the lube oil feed rate (LOFR) to deliver more basicity reserve during the piston motion in the cylinder. If this action is not sufficient it is necessary to switch to a Cylinder Oil with a higher BN. Nowadays, in the most modern engines and in line with the current OEM (Original Equipment Manufacturer) recommendations, corrosion can be avoided with Cylinder Oils of BN 100 mg KOH/g available on the market.
FAQ – BUNKERS
The value of fuel to the ship is the amount of energy that the ship can extract from the fuel. This is a function of mass of fuel rather than the volume. The practice of price per unit mass has been accepted for ships fuel for more than 100 years.
Although the three samples may have been taken from one bulk, continuous drip sample they could have different test results because the person who made up the three samples from the bulk failed to thoroughly stir/shake/blend the bulk sample before he poured into the three sample bottles. It can happen that if this is not done, heavier components of the fuel like Catalytic fines, water and other solids will not be proportional in all three samples.
Always witness the measurements on the barge. Almost all suppliers will only accept barge (or RTW or Shore tank) figures as conclusive. If your staff do not agree to the actual soundings, insist that they are taken again immediately. If your staff do not agree to the calculations, sign for soundings only and protest the calculated volume.
It is very difficult to substantiate a claim based on difference between barge and ship calculated figures but remember that most barges load and discharge every day whilst a ship will only bunker once a month. Barge tanks are cargo tanks and calibrated as such. Ship bunker tanks are usually not calibrated at all but measurements are taken from the original drawings.